1. The document discusses various epidemiological measures used to assess disease occurrence and guide public health decisions, including risk, prevalence, and incidence rate.
2. It provides examples and definitions for each measure, such as risk being the likelihood of contracting a disease, prevalence being the current number of existing cases, and incidence rate being the speed at which new cases develop.
3. Key relationships between the measures are explained, such as how prevalence is calculated based on incidence rate and average disease duration. Calculating these measures accurately requires addressing challenges like clearly defining cases and collecting complete data.
This document discusses various study designs used in medical research, including observational and experimental designs. It describes descriptive, analytical, and interventional studies. It provides examples of case reports, case series, cross-sectional studies, case-control studies, and cohort studies. It discusses key aspects of case-control studies such as selection of cases and controls, matching, determining exposure, and analyzing results. It also covers limitations and advantages of different study designs.
This document discusses epidemiological concepts related to causation and measures of disease occurrence. It defines a sufficient cause as a minimal set of conditions that inevitably produce disease. It discusses how interactions between component causes can affect disease risk. It also covers Hill's criteria for evaluating causation. The document defines key measures used to assess disease occurrence, including risk, prevalence, and incidence rate. It provides examples to illustrate how to calculate each measure and explains how they can help guide decisions in patient care and disease prevention.
February 9, 2018
In the past several years, the United States has struggled to respond to viral outbreaks, such as Ebola and Zika. There is now an awareness of the need to rapidly develop vaccines and treatments for epidemics that can quickly spread from country to country. But questions remain as how to best conduct clinical trials and development of vaccines in the context of an epidemic or outbreak.
At this panel discussion, two health policy experts examined the appropriate conduct of clinical trials during public health emergencies.
Learn more at: http://petrieflom.law.harvard.edu/events/details/clinical-trials-during-public-health-emergencies
This document discusses investigating disease outbreaks. It explains key concepts like immunity, herd immunity, incubation periods, and factors that warrant an investigation. It then summarizes an investigation of a gastrointestinal illness outbreak among college students. Interviews and a questionnaire found most cases ate lamb gravy at lunch, with a median incubation period of 10 hours, suggesting Clostridium perfringens food poisoning. The investigation identified the contaminated food source and helped control the outbreak. Overall, the document outlines approaches for outbreak investigation including descriptive and analytic epidemiology to identify causes and prevent further spread.
The values of clinical practice - Jordi VarelaJordi Varela
Three key principles will guide clinical practice: adding value to patient health, organizing doctors according to clinical processes, and measuring outcomes adjusted for risk and cost. Right care considers benefits and harms, is patient-centered, and evidence-based. Half of surgeries and clinical trials lack evidence to support them. Overdiagnosis leads to unnecessary treatment complications. Fragmented care for chronic patients results in clinical instability, unnecessary tests and costs. Clinical value practices aim to reduce wasteful spending through protocols, teamwork and learning from errors.
The document discusses sepsis and neutropenic sepsis in cancer patients. It provides guidelines from NICE on the management of sepsis and neutropenic sepsis, including the importance of early antibiotic administration. It also discusses outcomes for neutropenic and non-neutropenic sepsis in oncology patients, common pathogens that cause sepsis, and nosocomial infections. Throughout, it emphasizes the importance of early recognition and treatment of sepsis to improve outcomes.
Step 1: The document summarizes the steps of an epidemic investigation, beginning with confirming the existence of an outbreak, verifying the diagnosis, and gathering case information.
Step 2: Key steps include developing a case definition, finding additional cases, collecting information on individual cases, and analyzing patterns among cases to generate hypotheses. Hypotheses are then tested using analytical studies.
Step 3: The investigation also draws conclusions, reports findings to authorities, recommends control measures, communicates results to educate the public, and follows up to ensure recommendations are implemented. The overall goal is to control the current epidemic and prevent future outbreaks.
This document discusses various study designs used in medical research, including observational and experimental designs. It describes descriptive, analytical, and interventional studies. It provides examples of case reports, case series, cross-sectional studies, case-control studies, and cohort studies. It discusses key aspects of case-control studies such as selection of cases and controls, matching, determining exposure, and analyzing results. It also covers limitations and advantages of different study designs.
This document discusses epidemiological concepts related to causation and measures of disease occurrence. It defines a sufficient cause as a minimal set of conditions that inevitably produce disease. It discusses how interactions between component causes can affect disease risk. It also covers Hill's criteria for evaluating causation. The document defines key measures used to assess disease occurrence, including risk, prevalence, and incidence rate. It provides examples to illustrate how to calculate each measure and explains how they can help guide decisions in patient care and disease prevention.
February 9, 2018
In the past several years, the United States has struggled to respond to viral outbreaks, such as Ebola and Zika. There is now an awareness of the need to rapidly develop vaccines and treatments for epidemics that can quickly spread from country to country. But questions remain as how to best conduct clinical trials and development of vaccines in the context of an epidemic or outbreak.
At this panel discussion, two health policy experts examined the appropriate conduct of clinical trials during public health emergencies.
Learn more at: http://petrieflom.law.harvard.edu/events/details/clinical-trials-during-public-health-emergencies
This document discusses investigating disease outbreaks. It explains key concepts like immunity, herd immunity, incubation periods, and factors that warrant an investigation. It then summarizes an investigation of a gastrointestinal illness outbreak among college students. Interviews and a questionnaire found most cases ate lamb gravy at lunch, with a median incubation period of 10 hours, suggesting Clostridium perfringens food poisoning. The investigation identified the contaminated food source and helped control the outbreak. Overall, the document outlines approaches for outbreak investigation including descriptive and analytic epidemiology to identify causes and prevent further spread.
The values of clinical practice - Jordi VarelaJordi Varela
Three key principles will guide clinical practice: adding value to patient health, organizing doctors according to clinical processes, and measuring outcomes adjusted for risk and cost. Right care considers benefits and harms, is patient-centered, and evidence-based. Half of surgeries and clinical trials lack evidence to support them. Overdiagnosis leads to unnecessary treatment complications. Fragmented care for chronic patients results in clinical instability, unnecessary tests and costs. Clinical value practices aim to reduce wasteful spending through protocols, teamwork and learning from errors.
The document discusses sepsis and neutropenic sepsis in cancer patients. It provides guidelines from NICE on the management of sepsis and neutropenic sepsis, including the importance of early antibiotic administration. It also discusses outcomes for neutropenic and non-neutropenic sepsis in oncology patients, common pathogens that cause sepsis, and nosocomial infections. Throughout, it emphasizes the importance of early recognition and treatment of sepsis to improve outcomes.
Step 1: The document summarizes the steps of an epidemic investigation, beginning with confirming the existence of an outbreak, verifying the diagnosis, and gathering case information.
Step 2: Key steps include developing a case definition, finding additional cases, collecting information on individual cases, and analyzing patterns among cases to generate hypotheses. Hypotheses are then tested using analytical studies.
Step 3: The investigation also draws conclusions, reports findings to authorities, recommends control measures, communicates results to educate the public, and follows up to ensure recommendations are implemented. The overall goal is to control the current epidemic and prevent future outbreaks.
This document discusses hypothyroidism. It defines hypothyroidism as a hormonal deficiency caused by dysfunction of the thyroid gland that interrupts the synthesis and secretion of T4 and TSH. It discusses the epidemiology, risk factors, classifications, clinical manifestations, diagnosis, screening, and treatment of hypothyroidism. It notes that the prevalence is estimated to be 1-7% of the population and is more common in women and older adults. Diagnosis is based on elevated TSH and low free T4 levels. Treatment goals are to normalize TSH levels and improve symptoms.
This document provides information about a syphilis outbreak in Wake County, North Carolina. Syphilis case numbers are at a 15-year high in Wake County, with 245 cases reported in 2015. The outbreak is affecting primarily men who have sex with men (MSM), with 92% of 2015 cases occurring among men. Public health officials are working to identify and treat infected individuals, prevent further transmission, and help stop the outbreak. Physicians are required by law to report syphilis and other sexually transmitted disease cases to county and state health departments.
A case-control study of 23 anencephalic pregnancies and 92 control pregnancies examined associations between anencephaly and maternal characteristics and exposures. Well water consumption had the strongest association with anencephaly (OR=1.7, 95% CI 1.1-2.6), suggesting it may have caused the increase. Additional questions could help clarify the relationship between well water and anencephaly.
This document summarizes MRF's healthcare initiative in Malawi to improve recognition and treatment of meningitis at the primary health level. The initiative developed a triage system using a mobile health tool to classify patients into emergency, priority, and queue categories. The triage system was implemented in 5 primary health clinics in Blantyre, where it led to quicker patient wait times and improved teamwork among health staff. While over 60% of referred patients did not reach the tertiary hospital, the triage system accurately classified patients and showed potential to strengthen primary healthcare responses to illness in Malawi when scaled up.
This study aimed to determine if introducing a high-sensitivity cardiac troponin I (hs-cTnI) assay would improve clinical outcomes for patients with suspected acute coronary syndrome. The study was a stepped-wedge, cluster-randomized controlled trial across 10 hospitals in Scotland. It found that the hs-cTnI assay reclassified 17% of patients with myocardial injury or infarction not identified by the standard assay. However, among reclassified patients, the incidence of subsequent heart attack or cardiovascular death within 1 year was not significantly different after implementing the new assay. The findings question whether the diagnostic threshold for heart attack should be based on the 99th percentile from a normal population.
Concept of sufficient cause and component causesamitakashyap1
This document discusses key epidemiological concepts related to measuring disease occurrence, including sufficient causes, component causes, risk, prevalence, and incidence rate. It provides examples to illustrate how these measures are calculated and how they relate to one another. For example, it notes that prevalence is equal to incidence multiplied by disease duration when rates are stable over time. The document also discusses problems that can arise in measuring these variables and how changes in incidence and prevalence over time can provide insights into disease dynamics.
This study analyzed 114 cases of neonatal Candida bloodstream infection from a tertiary care hospital in central India over 5 years. Non-albicans Candida (NAC) infections like C. tropicalis and C. parapsilosis were associated with higher mortality and longer hospital stays. Resistance to fluconazole and amphotericin B was also higher in NAC infections. Prolonged use of central lines, nil oral intake, mechanical ventilation and longer hospital stays were identified as risk factors. The study highlights the need for timely identification of Candida species and antifungal susceptibility testing to help improve outcomes.
This study aimed to compare the ability of serial cranial ultrasounds (CUS) and early MRI scans in detecting preterm brain injuries. The study found that CUS allowed for more scans due to better feasibility in the NICU, and was better at detecting grade I-II intraventricular hemorrhages and perforator strokes. MRI was superior for identifying smaller cerebellar hemorrhages and provided more quantitative data. Overall, the combination of serial CUS and MRI provided the highest sensitivity for detecting common preterm brain injuries, though MRI could not be performed in the sickest infants.
This study assessed the prevalence of dengue cases in North 24 Parganas District, West Bengal, India from 2012-2015. A total of 3281 laboratory-confirmed dengue cases were reported during this period. Dengue transmission was found to be seasonal from June to November, but most intense from August to October. Young adults aged 16-45 years accounted for 49% of cases and were at greatest risk of infection. Dengue severity was identified in 121 cases (3.68%) of dengue hemorrhagic fever and dengue shock syndrome, with 11 deaths (0.33%). The Breteau index, a measure of Aedes mosquito density, ranged from 4-24 during peak transmission seasons. The
This document discusses evidence-based guidelines for diabetes treatment. It addresses where clinical judgement comes from, including tradition, authority, science, analysis of evidence, and personal factors. It also discusses the concept of evidence, the rise of "robot physicians" following guidelines rigidly, and issues with how guidelines are developed and can extend disease boundaries and therapeutic futility. Overall, the document questions some aspects of clinical practice guidelines and their relationship to evidence, authority, and competing interests.
Azithromycin was found to be non-inferior but not superior to doxycycline for treating urogenital Chlamydia trachomatis infection in a randomized controlled trial of 567 youths in correctional facilities. The efficacy of azithromycin was 97% compared to 100% for doxycycline. While both treatments had similar adverse effect profiles, doxycycline demonstrated no treatment failures compared to 5 failures in the azithromycin group. The authors concluded that doxycycline is up to 100% efficacious for treating chlamydia in mostly adherent patients, whereas azithromycin efficacy may be slightly lower with occasional treatment failures.
This outbreak investigation identified an outbreak of E. coli O157:H7 infections in Michigan in June-July 1997. Initial calls reported 6 patients infected. Molecular fingerprinting of isolates found they were identical, confirming an outbreak. A case-control study identified alfalfa sprout consumption as the likely source, with an odds ratio of 25. Traceback studies traced the implicated sprouts to contaminated seed lots from Idaho alfalfa fields, possibly due to cattle manure, irrigation water, or deer feces. Further studies cultured implicated sprouts and investigated contamination routes on alfalfa farms.
This document outlines the steps for investigating an outbreak. It defines key epidemiological terms and discusses when to investigate an outbreak. The 10 steps of an outbreak investigation are described as: 1) defining the problem, 2) generating hypotheses, 3) testing hypotheses, 4) verifying diagnoses, 5) finding and counting cases, 6) performing descriptive epidemiology, 7) analyzing data, 8) communicating findings, 9) implementing control measures, and 10) preventing future outbreaks. Preparedness, the roles of NGOs, recent outbreak examples, and the importance of surveillance and inter-sectoral coordination are also covered.
The document argues that the Pfizer COVID-19 vaccine kills more people than it saves based on several calculations and studies. It claims the excess death to life ratio for the Pfizer vaccine in clinical trials and databases like VAERS is unacceptable. It also argues that reports of adverse events are much higher than baseline levels and reports of fraud in Pfizer's clinical trials have not been properly investigated. Alternative early treatment options are presented as safer alternatives.
The document outlines the key principles and steps of conducting an outbreak investigation. It defines what constitutes an outbreak and explains that the purpose is to control the current outbreak, prevent future occurrences, and evaluate existing surveillance and prevention programs. The main steps described are confirming the outbreak, defining cases, collecting descriptive data, developing hypotheses, testing hypotheses through analytical studies, communicating conclusions, and recommending control measures.
This document outlines the steps for investigating an outbreak of infectious disease:
1. Verify the diagnosis and define cases. Develop a case definition based on clinical criteria.
2. Establish that an outbreak exists by determining if cases exceed normal levels. Avoid pseudo-outbreaks from improved reporting.
3. Identify and count cases through active and passive surveillance. Take histories and examine all confirmed and suspected cases.
4. Perform descriptive epidemiology including time, place, and person analyses to generate hypotheses about the source and transmission of the disease.
5. Implement control measures as soon as possible before confirming the source to break the chain of infection. Measures include notification, isolation, and quarantine.
The document summarizes the key steps in investigating an epidemic:
1) Verify the diagnosis and confirm the existence of an epidemic by comparing to previous years.
2) Define the population at risk by obtaining maps, counting population size, and initial line-listing of cases.
3) Conduct a rapid search for all cases through medical surveys, case sheets collecting details of identified cases, and searching for additional cases.
4) Analyze the collected data to understand patterns in time, place and person which can reveal the source and spread of disease. Formulate and test hypotheses based on this analysis.
This document outlines the steps involved in investigating an epidemic:
1. Verification of diagnoses and defining cases is the first step to understand the scope and characteristics of the epidemic.
2. Confirmation of an actual epidemic involves comparing case numbers to historical data to determine if there is unusual disease occurrence.
3. Defining the population at risk, rapidly searching for all cases, collecting data on characteristics, and analyzing patterns in time, place and person help identify potential causes and transmission routes.
Personalising Medicine - The Hard Way or the Easy Way (linkedin)sgardne0
This document discusses the promise and challenges of personalized medicine. It begins by outlining the promise of using an individual's genomic and other health data to more accurately diagnose, treat, and manage disease. However, it notes that analyzing all the relevant factors for personalized medicine at scale currently poses immense computational challenges. The document then describes several case studies that demonstrate more effective approaches to personalized medicine using multi-trait analysis of many genomic and clinical factors. It argues that empowering individuals to better manage their own health using personalized digital tools could help shift healthcare outside of traditional settings and lower costs while improving outcomes.
Medical Surveillance and Outbreaks of Disease.pdfLuckyBoyCount
This document discusses key concepts in medical surveillance and epidemiology including:
- Medical surveillance involves the continuous collection of health data from a target population to identify disease patterns and outbreaks for prevention and control.
- Rates, proportions, and percentages are numerical metrics used to represent epidemiological findings. A rate is a ratio comparing two health measures over time.
- Morbidity refers to disease burden while mortality refers to deaths. Incidence measures new cases over time while prevalence measures all current cases.
- Correct classification of disease, symptoms, and exposures is important for epidemiological studies, as misclassification can bias results.
1. Incidence measures new cases of a disease over time in a population, while prevalence looks at all existing cases at a point or over a period of time.
2. Incidence can be expressed as a proportion or a rate incorporating time. Prevalence is always a proportion.
3. Examples are given calculating incidence proportion, incidence rate, and point and period prevalence from data. Morbidity measurements help describe disease burden and inform public health planning.
This document discusses hypothyroidism. It defines hypothyroidism as a hormonal deficiency caused by dysfunction of the thyroid gland that interrupts the synthesis and secretion of T4 and TSH. It discusses the epidemiology, risk factors, classifications, clinical manifestations, diagnosis, screening, and treatment of hypothyroidism. It notes that the prevalence is estimated to be 1-7% of the population and is more common in women and older adults. Diagnosis is based on elevated TSH and low free T4 levels. Treatment goals are to normalize TSH levels and improve symptoms.
This document provides information about a syphilis outbreak in Wake County, North Carolina. Syphilis case numbers are at a 15-year high in Wake County, with 245 cases reported in 2015. The outbreak is affecting primarily men who have sex with men (MSM), with 92% of 2015 cases occurring among men. Public health officials are working to identify and treat infected individuals, prevent further transmission, and help stop the outbreak. Physicians are required by law to report syphilis and other sexually transmitted disease cases to county and state health departments.
A case-control study of 23 anencephalic pregnancies and 92 control pregnancies examined associations between anencephaly and maternal characteristics and exposures. Well water consumption had the strongest association with anencephaly (OR=1.7, 95% CI 1.1-2.6), suggesting it may have caused the increase. Additional questions could help clarify the relationship between well water and anencephaly.
This document summarizes MRF's healthcare initiative in Malawi to improve recognition and treatment of meningitis at the primary health level. The initiative developed a triage system using a mobile health tool to classify patients into emergency, priority, and queue categories. The triage system was implemented in 5 primary health clinics in Blantyre, where it led to quicker patient wait times and improved teamwork among health staff. While over 60% of referred patients did not reach the tertiary hospital, the triage system accurately classified patients and showed potential to strengthen primary healthcare responses to illness in Malawi when scaled up.
This study aimed to determine if introducing a high-sensitivity cardiac troponin I (hs-cTnI) assay would improve clinical outcomes for patients with suspected acute coronary syndrome. The study was a stepped-wedge, cluster-randomized controlled trial across 10 hospitals in Scotland. It found that the hs-cTnI assay reclassified 17% of patients with myocardial injury or infarction not identified by the standard assay. However, among reclassified patients, the incidence of subsequent heart attack or cardiovascular death within 1 year was not significantly different after implementing the new assay. The findings question whether the diagnostic threshold for heart attack should be based on the 99th percentile from a normal population.
Concept of sufficient cause and component causesamitakashyap1
This document discusses key epidemiological concepts related to measuring disease occurrence, including sufficient causes, component causes, risk, prevalence, and incidence rate. It provides examples to illustrate how these measures are calculated and how they relate to one another. For example, it notes that prevalence is equal to incidence multiplied by disease duration when rates are stable over time. The document also discusses problems that can arise in measuring these variables and how changes in incidence and prevalence over time can provide insights into disease dynamics.
This study analyzed 114 cases of neonatal Candida bloodstream infection from a tertiary care hospital in central India over 5 years. Non-albicans Candida (NAC) infections like C. tropicalis and C. parapsilosis were associated with higher mortality and longer hospital stays. Resistance to fluconazole and amphotericin B was also higher in NAC infections. Prolonged use of central lines, nil oral intake, mechanical ventilation and longer hospital stays were identified as risk factors. The study highlights the need for timely identification of Candida species and antifungal susceptibility testing to help improve outcomes.
This study aimed to compare the ability of serial cranial ultrasounds (CUS) and early MRI scans in detecting preterm brain injuries. The study found that CUS allowed for more scans due to better feasibility in the NICU, and was better at detecting grade I-II intraventricular hemorrhages and perforator strokes. MRI was superior for identifying smaller cerebellar hemorrhages and provided more quantitative data. Overall, the combination of serial CUS and MRI provided the highest sensitivity for detecting common preterm brain injuries, though MRI could not be performed in the sickest infants.
This study assessed the prevalence of dengue cases in North 24 Parganas District, West Bengal, India from 2012-2015. A total of 3281 laboratory-confirmed dengue cases were reported during this period. Dengue transmission was found to be seasonal from June to November, but most intense from August to October. Young adults aged 16-45 years accounted for 49% of cases and were at greatest risk of infection. Dengue severity was identified in 121 cases (3.68%) of dengue hemorrhagic fever and dengue shock syndrome, with 11 deaths (0.33%). The Breteau index, a measure of Aedes mosquito density, ranged from 4-24 during peak transmission seasons. The
This document discusses evidence-based guidelines for diabetes treatment. It addresses where clinical judgement comes from, including tradition, authority, science, analysis of evidence, and personal factors. It also discusses the concept of evidence, the rise of "robot physicians" following guidelines rigidly, and issues with how guidelines are developed and can extend disease boundaries and therapeutic futility. Overall, the document questions some aspects of clinical practice guidelines and their relationship to evidence, authority, and competing interests.
Azithromycin was found to be non-inferior but not superior to doxycycline for treating urogenital Chlamydia trachomatis infection in a randomized controlled trial of 567 youths in correctional facilities. The efficacy of azithromycin was 97% compared to 100% for doxycycline. While both treatments had similar adverse effect profiles, doxycycline demonstrated no treatment failures compared to 5 failures in the azithromycin group. The authors concluded that doxycycline is up to 100% efficacious for treating chlamydia in mostly adherent patients, whereas azithromycin efficacy may be slightly lower with occasional treatment failures.
This outbreak investigation identified an outbreak of E. coli O157:H7 infections in Michigan in June-July 1997. Initial calls reported 6 patients infected. Molecular fingerprinting of isolates found they were identical, confirming an outbreak. A case-control study identified alfalfa sprout consumption as the likely source, with an odds ratio of 25. Traceback studies traced the implicated sprouts to contaminated seed lots from Idaho alfalfa fields, possibly due to cattle manure, irrigation water, or deer feces. Further studies cultured implicated sprouts and investigated contamination routes on alfalfa farms.
This document outlines the steps for investigating an outbreak. It defines key epidemiological terms and discusses when to investigate an outbreak. The 10 steps of an outbreak investigation are described as: 1) defining the problem, 2) generating hypotheses, 3) testing hypotheses, 4) verifying diagnoses, 5) finding and counting cases, 6) performing descriptive epidemiology, 7) analyzing data, 8) communicating findings, 9) implementing control measures, and 10) preventing future outbreaks. Preparedness, the roles of NGOs, recent outbreak examples, and the importance of surveillance and inter-sectoral coordination are also covered.
The document argues that the Pfizer COVID-19 vaccine kills more people than it saves based on several calculations and studies. It claims the excess death to life ratio for the Pfizer vaccine in clinical trials and databases like VAERS is unacceptable. It also argues that reports of adverse events are much higher than baseline levels and reports of fraud in Pfizer's clinical trials have not been properly investigated. Alternative early treatment options are presented as safer alternatives.
The document outlines the key principles and steps of conducting an outbreak investigation. It defines what constitutes an outbreak and explains that the purpose is to control the current outbreak, prevent future occurrences, and evaluate existing surveillance and prevention programs. The main steps described are confirming the outbreak, defining cases, collecting descriptive data, developing hypotheses, testing hypotheses through analytical studies, communicating conclusions, and recommending control measures.
This document outlines the steps for investigating an outbreak of infectious disease:
1. Verify the diagnosis and define cases. Develop a case definition based on clinical criteria.
2. Establish that an outbreak exists by determining if cases exceed normal levels. Avoid pseudo-outbreaks from improved reporting.
3. Identify and count cases through active and passive surveillance. Take histories and examine all confirmed and suspected cases.
4. Perform descriptive epidemiology including time, place, and person analyses to generate hypotheses about the source and transmission of the disease.
5. Implement control measures as soon as possible before confirming the source to break the chain of infection. Measures include notification, isolation, and quarantine.
The document summarizes the key steps in investigating an epidemic:
1) Verify the diagnosis and confirm the existence of an epidemic by comparing to previous years.
2) Define the population at risk by obtaining maps, counting population size, and initial line-listing of cases.
3) Conduct a rapid search for all cases through medical surveys, case sheets collecting details of identified cases, and searching for additional cases.
4) Analyze the collected data to understand patterns in time, place and person which can reveal the source and spread of disease. Formulate and test hypotheses based on this analysis.
This document outlines the steps involved in investigating an epidemic:
1. Verification of diagnoses and defining cases is the first step to understand the scope and characteristics of the epidemic.
2. Confirmation of an actual epidemic involves comparing case numbers to historical data to determine if there is unusual disease occurrence.
3. Defining the population at risk, rapidly searching for all cases, collecting data on characteristics, and analyzing patterns in time, place and person help identify potential causes and transmission routes.
Personalising Medicine - The Hard Way or the Easy Way (linkedin)sgardne0
This document discusses the promise and challenges of personalized medicine. It begins by outlining the promise of using an individual's genomic and other health data to more accurately diagnose, treat, and manage disease. However, it notes that analyzing all the relevant factors for personalized medicine at scale currently poses immense computational challenges. The document then describes several case studies that demonstrate more effective approaches to personalized medicine using multi-trait analysis of many genomic and clinical factors. It argues that empowering individuals to better manage their own health using personalized digital tools could help shift healthcare outside of traditional settings and lower costs while improving outcomes.
Medical Surveillance and Outbreaks of Disease.pdfLuckyBoyCount
This document discusses key concepts in medical surveillance and epidemiology including:
- Medical surveillance involves the continuous collection of health data from a target population to identify disease patterns and outbreaks for prevention and control.
- Rates, proportions, and percentages are numerical metrics used to represent epidemiological findings. A rate is a ratio comparing two health measures over time.
- Morbidity refers to disease burden while mortality refers to deaths. Incidence measures new cases over time while prevalence measures all current cases.
- Correct classification of disease, symptoms, and exposures is important for epidemiological studies, as misclassification can bias results.
1. Incidence measures new cases of a disease over time in a population, while prevalence looks at all existing cases at a point or over a period of time.
2. Incidence can be expressed as a proportion or a rate incorporating time. Prevalence is always a proportion.
3. Examples are given calculating incidence proportion, incidence rate, and point and period prevalence from data. Morbidity measurements help describe disease burden and inform public health planning.
Based on the information provided, the co-chairpersons of the study were:
- Jens D. Lundgren, M.D.
- Abdel G.Babiker, Ph.D.
- Fred Gordin, M.D.
They, along with other members of the INSIGHT START Study Group, assume responsibility for the overall content and integrity of the article.
mudule 3 Measure of health and Health Related Events.pdfteddiyfentaw
This document discusses various measures used to quantify health and disease in populations. It begins by defining key concepts like ratios, proportions, and rates. It then examines measures of morbidity like incidence rate and prevalence. Measures of mortality such as case-fatality rate and proportionate mortality ratio are also introduced. The document concludes by explaining measures of association between exposure and disease, including relative risk, odds ratio, and impact measures like attributable risk.
This document discusses case control studies and provides examples to illustrate their use. It defines a case control study as an epidemiological approach that starts with identified "cases" who have a disease and compares them to "controls" who do not have the disease. The study then examines past exposure history to identify potential risk factors.
Key aspects of case control studies covered include selecting appropriate cases and controls, matching on important variables, measuring past exposure, calculating odds ratios to estimate disease risk associated with exposures, and potential biases like selection bias, recall bias, and survivorship bias. Examples are provided of early case control studies that helped identify links between smoking and lung cancer, and between rubella infection and cataracts.
1. The document discusses key concepts in epidemiology including rates, ratios, proportions, incidence, prevalence and the epidemiological triad of agent, host, and environment.
2. It provides examples and definitions for rates, ratios, proportions, incidence, prevalence and how they are calculated and what each measures.
3. The epidemiological triad is explained as the relationship between the agent that causes disease, the host or person, and the environment they interact in. Understanding this triad is important for studying how diseases are distributed in populations.
This document discusses community-acquired pneumonia (CAP). It defines CAP and outlines its epidemiology, noting risk factors like increasing age and winter season. Diagnosis involves clinical evaluation, chest imaging, and ruling out other causes if imaging is abnormal but symptoms aren't. Severity is assessed using scores like CURB-65 to determine appropriate treatment setting. Most ambulatory patients receive 5 days of antibiotics while hospitalized patients get broader empiric coverage. Adjunctive steroids may benefit severe cases. Proper follow up and prevention through vaccination and smoking cessation are also discussed.
MEASURES OF DISEASE FREQUENCY. ASSOSCIATION AND IMPACTAneesa K Ayoob
This document discusses various measures used to quantify disease frequency, association, and impact in epidemiology. It defines key terms like incidence, prevalence, risk, rate, and ratio. For measures of disease frequency, it distinguishes between incidence, which considers new cases over time, and prevalence, which includes all current cases. Measures of association like relative risk and odds ratio quantify the relationship between exposure and outcome by comparing disease occurrence between exposed and unexposed groups. Measures of impact, such as attributable risk, indicate the extent to which a disease can be attributed to a given exposure.
This document discusses various epidemiological measurements used to measure health in populations. It defines key terms like incidence, prevalence, rates, ratios and proportions. It provides examples and formulas to calculate mortality rates like crude death rate, cause-specific death rates. The document also explains the difference between incidence and prevalence and how they are related. It discusses the importance of standardization to make rates comparable between populations and the methods of direct and indirect standardization.
Mesurement of morbidity (prevalence) presentationDrsadhana Meena
measurement of morbidity (prevalence ) presentation by dr. sadhana, sms medical college , jaipur
included all aspects related to prevalence - objectives,types,significance ,comparison between prevalence and incidence , practical example of prevalence.
The document discusses various methods for measuring disease occurrence and mortality rates in populations. It defines key epidemiological terms like incidence rate, prevalence rate, case fatality rate, crude death rate, age-specific death rates, cause-specific death rates, infant mortality rate, neonatal mortality rate, and maternal mortality ratio. Various factors that influence these rates are also explained. Examples are provided to demonstrate how to calculate different rates.
This document discusses various epidemiological measures used to describe the frequency and distribution of diseases in populations. It defines incidence as the number of new cases in a population during a specified time period. Incidence rate is calculated by dividing the number of new cases by the total population at risk. Prevalence refers to existing cases in the population at a given time. Incidence density accounts for person-time at risk and divides new cases by total person-years observed. Measures of association like relative risk and odds ratio are used to compare disease frequency between exposed and unexposed groups.
Epidemiology is the study of the distribution and determinants of health-related states or events in populations and the application of this study to control health problems. Basic measurements used in epidemiology include rates, ratios, and proportions to describe disease occurrence and burden. Rates measure events over time and include the crude death rate and incidence rate. Proportions compare a part to the whole without time. Ratios compare two rates or quantities. These measurements are essential tools for epidemiologists to investigate disease causation, describe population health, and evaluate interventions.
Dr. Frank Sullivan - Early diagnosis of lung cancerpincomm
The document discusses early diagnosis of lung cancer through potential screening programs utilizing low-dose CT scans and blood-based biomarkers. It describes:
1) Current poor outcomes of lung cancer diagnosed at late stages and potential for improved survival if detected earlier. A case study is presented of a patient whose cancer was found too late.
2) Ongoing research into using low-dose CT screening and blood-based biomarkers individually and together to detect lung cancer at earlier stages. Early results from a large Scottish trial combining CT and biomarkers show promising increases in operable cancers detected.
3) Key information needs and roles of primary care physicians in potential future organized lung cancer screening programs, as identified through focus groups in Ontario.
2010-Epidemiology (Dr. Sameem) basics and priciples.pptAmirRaziq1
Epidemiology is the study of the distribution and determinants of health-related states in populations. There are three main types of epidemiological studies: observational studies which examine risk factors without interfering; experimental (interventional) studies which manipulate factors; and descriptive studies which show disease patterns and frequencies. Case-control studies are retrospective and compare exposures in cases (diseased) and controls (non-diseased) to identify risk factors. Cohort studies are prospective and follow exposure groups over time to calculate disease incidence and identify risk factors. Cross-sectional studies provide a snapshot of disease prevalence and help generate hypotheses for further research.
This document discusses various uses and methods of epidemiology. Descriptive epidemiology characterizes disease distribution, leading to hypotheses about causes. Analytical epidemiology identifies causes by testing hypotheses. Distribution patterns (who, where, when) of disease occurrence can provide clues about risk factors and causation. Medical surveillance aims to identify disease patterns, outbreaks, and changing health needs. Hypotheses about disease causation can be developed by examining correlations between suspected risk factors and disease occurrence across populations, while accounting for potential biases. Age-standardization methods like direct standardization are used to adjust rates to account for differences in population age structures when making comparisons.
Epidemiology of tb with recent advances acknowledged by whoRama shankar
This document provides an overview of tuberculosis epidemiology and recent advances in tuberculosis programs. It discusses the global and national burden of tuberculosis, the evolution of tuberculosis control programs in India including the National Tuberculosis Control Programme and Revised National Tuberculosis Control Programme. It covers diagnosis, treatment, drug-resistant tuberculosis, tuberculosis and HIV coinfection, and recent advances acknowledged by the WHO. The post-2015 tuberculosis strategy in relation to sustainable development goals is also mentioned.
Epidemiology is the study of the distribution and determinants of health-related states or events in populations and the application of this study to control health problems. The basic measurements used in epidemiology include rates, ratios, and proportions to describe the occurrence of mortality, morbidity, disability, and other disease attributes in populations. Rates express the frequency of events over time, proportions express the relationship between parts and the whole, and ratios compare two rates or quantities. These measurements are essential tools for epidemiologists to investigate disease causation, describe population health status, and evaluate interventions.
1) In the first race, the hare sprints ahead but grows complacent and falls asleep, allowing the steady tortoise to win.
2) In the rematch, the determined hare runs consistently and wins.
3) In another rematch, the tortoise leads the hare to a river, where the hare cannot swim, allowing the tortoise to swim across and win again.
4) In the final race, the hare and tortoise work as a team, using each other's strengths to cross the finish line together faster than either could alone.
This document discusses principles and techniques for effective leadership and interpersonal relationships. It emphasizes building on one's authentic self to influence others through understanding relationships, providing purpose and motivation. It also discusses changing perceptions and mindsets, focusing on people rather than things, developing interdependence through mutual understanding and accountability, and the importance of listening, communication skills, and meeting psychological needs to develop synergistic relationships.
Effective public health communication oldamitakashyap1
Effective public health communication is essential for informing and influencing individuals and communities about important health issues. The document discusses various aspects of public health communication including defining it, the need for effective communication, principles of effective communication, challenges, and approaches like social marketing. It provides details on formative research conducted to develop a nutrition strategy in Rajasthan which included understanding audiences, behaviors, barriers and enablers. The strategy developed communication objectives and a plan for different audiences using various channels and materials. Monitoring indicators were also identified to track outcomes. Such a thorough, evidence-based approach can enable replicable and sustainable public health communication programs.
1) Cohort studies begin with groups of individuals who are alike in many ways but differ with respect to exposure to a certain factor, thought to influence the probability of occurrence of a disease or other outcome.
2) The groups are followed over time and the researchers record who does or does not develop the disease. This allows calculation of disease rates in the exposed and unexposed groups.
3) Cohort studies can provide strong evidence about whether an association reflects a causal relationship by assessing disease development over time in relation to exposure. However, selection bias and information bias must be considered.
Effective public health communication 5th aprilamitakashyap1
Effective public health communication is needed to promote awareness of health issues, educate about available services, change behaviors to improve health, address emergencies, and build community capacity. It should be relevant, accurate, culturally competent, accessible, and action-oriented. Types of public health communication include health education, advocacy, risk communication, and crisis communication. Social marketing uses commercial techniques to promote social causes like improving nutrition. Developing effective public health communication requires understanding the community through formative research, developing multilevel strategies, pre-testing materials, and monitoring outcomes. An example from Rajasthan developed a state-specific strategy to address undernutrition through behavior change communication targeting pregnant women, husbands, mothers-in-law and health workers
The document discusses the benefits of meditation for reducing stress and anxiety. Regular meditation practice can help calm the mind and body by lowering heart rate and blood pressure. Studies have shown that meditating for just 10-20 minutes per day can have significant positive impacts on both mental and physical health.
This document provides information on various contraceptive methods, including spacing and terminal methods. Spacing methods are used to space births or delay the first child, and include barrier methods, IUDs, hormonal methods, fertility awareness methods, and lactational amenorrhea. Terminal methods permanently stop conception and include vasectomy for men and tubal ligation for women. The document describes the composition, mode of action, effectiveness, advantages, and disadvantages of common contraceptive methods such as condoms, IUDs, oral contraceptive pills, injectables, implants, sterilization procedures, and fertility awareness methods.
This document discusses various indicators that can be used to measure health and disease in a population. It outlines different types of indicators including health status indicators like mortality and morbidity, quality of life indicators, socioeconomic indicators, health care delivery indicators, and environmental indicators. Specific measures are provided for different types of indicators, such as crude mortality rate, standardized mortality rates, incidence rate, and prevalence. The indicators can help health administrators assess problems, design health plans, and evaluate schemes. Ideal indicators should be valid, reliable, sensitive, specific, and feasible.
This document discusses concepts related to disease transmission. It defines the epidemiologic triad as requiring an agent, reservoir, mode of transmission, portal of entry and susceptible host. Modes of transmission include direct contact or indirect transmission through vehicles or vectors. Disease levels range from sporadic to endemic to epidemic or pandemic. Herd immunity is achieved through vaccination above a threshold proportion of immune individuals. Types of epidemics include common source, propagated or mixed spread. Body surfaces and routes of exposure allow entry of infectious agents.
Public health originated in the 19th century to address poor sanitary conditions and disease outbreaks. Simple public health measures like clean water and vaccination have saved more lives than medical advances. Community medicine focuses on preventing disease in populations through organized community efforts. It aims to promote health and adjust individuals and society. Public health is defined as organized efforts to prevent disease, prolong life, and promote health through surveillance, policies, education, and ensuring resources are allocated to public health. It uses technology and social sciences to identify, prevent and monitor health issues in populations.
Community medicine focuses on preventing disease and promoting public health rather than treating individual patients. It evolved from public health movements in the 19th century that emphasized sanitation and organized community efforts to improve health. Community medicine aims to keep populations healthy through measures like vaccination programs, vector control, and increasing access to resources like safe water and adequate nutrition. It has contributed greatly to reducing communicable diseases and improving health worldwide.
This document discusses key concepts in public health and community medicine. It defines public health as the science and art of preventing disease, prolonging life, and promoting health through organized community efforts. The document outlines the importance and evolution of public health interventions and movements. It also compares clinical and preventive medicine and discusses the contributions, functions, and future of community medicine and public health.
Community medicine focuses on health promotion and disease prevention at the community level through organized social action. It evolved from clinical medicine to address health issues facing entire populations. Key concepts include viewing health as an equilibrium between individuals and their environment, the importance of both preventive and curative approaches to medicine, and addressing social determinants of health. The field was influenced by developments in epidemiology, public health infrastructure, and the germ theory of disease.
1. An outbreak investigation was conducted to determine the source and mode of transmission of an illness that exceeded expected numbers. Interviews, specimen collection, and data analysis were performed.
2. Analysis revealed the pathogen and identified a water source as the likely mode of transmission. Over 100 cases were reported in the affected area within two weeks.
3. Recommendations included controlling the contaminated water source, strengthening surveillance, and preventing future outbreaks through improved sanitation.
This document discusses key concepts related to disease transmission including:
1. The epidemiologic triad of an agent, host, and environment being required for disease transmission.
2. Various host, agent, and environmental factors that influence transmission risk.
3. Common modes of transmission like direct contact or indirect transmission through vehicles or vectors.
4. Key epidemiological terms like outbreak, epidemic, pandemic, and the differences between clinical and subclinical disease.
This document discusses sampling distributions and their use in making statistical inferences from data. It begins by defining key aspects of sampling distributions, including the statistic of interest (e.g. mean, proportion), random selection of samples, sample size, and population. It then generates a sampling distribution using an example of calculating the mean number of months since patients' last medical examination across different samples. The document outlines important characteristics of sampling distributions and how the central limit theorem applies. It also discusses how to construct confidence intervals and conduct hypothesis testing using sampling distributions.
This document discusses the gold standard for establishing causality - the randomized clinical trial. It provides an overview of key elements of randomized trials including randomization, masking/blinding, study design issues, and problems with noncompliance. It discusses the purpose of randomized trials for evaluating new treatments, tests, programs, and health services. Examples are provided of some early non-randomized trials from the 15th-18th centuries. Key aspects of planning a randomized trial such as defining the research question, outcomes, sample size calculation, and randomization procedure are also covered.
This document describes different study designs used in medical research including observational and experimental studies. Observational studies are further divided into descriptive studies that examine disease patterns and analytical studies that study suspected causes of disease. Experimental studies compare treatment modalities. Case-control and cohort studies are described as important analytical observational designs. Case-control studies compare exposures among cases and controls to study the association between exposure and disease. Cohort studies prospectively follow subjects exposed and unexposed to an exposure to study disease outcomes. Key aspects of selecting subjects and exposures as well as analyzing these study designs are discussed.
This document discusses five ways of describing the natural history of a disease: case-fatality, five-year survival, observed survival, median survival time, and relative survival. It describes how to calculate observed survival over time using life tables and the Kaplan-Meier method. Improvements in diagnostic methods can affect prognosis estimates by changing disease staging (stage migration). The document provides examples of using life tables and Kaplan-Meier analyses to quantify survival rates and compare outcomes with and without new treatments.
A 29-year-old previously healthy man was referred to UCLA with a 8-month history of fever, fatigue, enlarged lymph nodes, and a 12.5 kg weight loss. He had a fever of 39.5°C, appeared physically wasted, and had swollen lymph nodes. Laboratory tests showed depressed lymphocytes. The patient suffered from simultaneous infections of Candida albicans in the upper gastrointestinal tract, Pneumocystis carinii in the lungs, and cytomegalovirus in the urinary tract, and was not responding to antibiotics with no known cause of immunosuppression. There were also 3 other previously healthy young men in the last 6 months reported with similar symptoms who all had Candida albic
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Local Advanced Lung Cancer: Artificial Intelligence, Synergetics, Complex Sys...Oleg Kshivets
Overall life span (LS) was 1671.7±1721.6 days and cumulative 5YS reached 62.4%, 10 years – 50.4%, 20 years – 44.6%. 94 LCP lived more than 5 years without cancer (LS=2958.6±1723.6 days), 22 – more than 10 years (LS=5571±1841.8 days). 67 LCP died because of LC (LS=471.9±344 days). AT significantly improved 5YS (68% vs. 53.7%) (P=0.028 by log-rank test). Cox modeling displayed that 5YS of LCP significantly depended on: N0-N12, T3-4, blood cell circuit, cell ratio factors (ratio between cancer cells-CC and blood cells subpopulations), LC cell dynamics, recalcification time, heparin tolerance, prothrombin index, protein, AT, procedure type (P=0.000-0.031). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and N0-12 (rank=1), thrombocytes/CC (rank=2), segmented neutrophils/CC (3), eosinophils/CC (4), erythrocytes/CC (5), healthy cells/CC (6), lymphocytes/CC (7), stick neutrophils/CC (8), leucocytes/CC (9), monocytes/CC (10). Correct prediction of 5YS was 100% by neural networks computing (error=0.000; area under ROC curve=1.0).
These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
9. Define mean electrical vector (axis) of the heart and give the normal range
10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
- Video recording of this lecture in English language: https://youtu.be/kqbnxVAZs-0
- Video recording of this lecture in Arabic language: https://youtu.be/SINlygW1Mpc
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
ABDOMINAL TRAUMA in pediatrics part one.drhasanrajab
Abdominal trauma in pediatrics refers to injuries or damage to the abdominal organs in children. It can occur due to various causes such as falls, motor vehicle accidents, sports-related injuries, and physical abuse. Children are more vulnerable to abdominal trauma due to their unique anatomical and physiological characteristics. Signs and symptoms include abdominal pain, tenderness, distension, vomiting, and signs of shock. Diagnosis involves physical examination, imaging studies, and laboratory tests. Management depends on the severity and may involve conservative treatment or surgical intervention. Prevention is crucial in reducing the incidence of abdominal trauma in children.
Osteoporosis - Definition , Evaluation and Management .pdfJim Jacob Roy
Osteoporosis is an increasing cause of morbidity among the elderly.
In this document , a brief outline of osteoporosis is given , including the risk factors of osteoporosis fractures , the indications for testing bone mineral density and the management of osteoporosis
Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
2. A Patient’S Profile:
• A 60 year old previously healthy female, research
chemist recently developed shortness of breadth and
nose bleeding.
• Pale, pulse 110/ min, low (20%) hematocrit, elevated
(20000/l) leukocyte counts, low platelet (15000/l)
with PBF showing atypical myeloblasts
• Hospitalized for Suspected acute myelogenous
leukemia; confirmed by bone marrow aspirate and
biopsy.
• Chemotherapy started, about 3 weeks later, her temp.
abruptly rose to 39C and neutrophil count dropped to
100 /l.
• No source of apparent infection;
3. Patient Profile…ctd:
• Importance of Risk assessment!!
• How likely is it that patient has a bacterial
infection?
• Her blood and urine cultures were taken, and
broad spectrum antibiotics administered (empiric
treatment)
• Potential Risk of complications from delayed
antibiotic outweighed empiric use of antibiotic
• Cultures confirmed staphylococcus aureus in blood
4. Measures of Disease Occurrence
Epidemiologic measures - to assess outcomes
and thereby guide decisions
• Risk (the likelihood that a person will contract a
disease)
• Prevalence (Load; the amount of disease
already present in the population)
• Incidence Rate (how fast is the new occurrence
of disease)
5. Defined
Population
Have
Disease
Do not
have
disease
Do not have
disease at
baseline
PAR
Prevalent
cases
1. Identify
Population
3. Follow
only those
who did not
have the dis.
2. Determine
who has the Dis.
& who doesn’t
Do not have
disease at
baseline
Develop Dis.
Do not have
disease
Follow up for 1 year
incident
cases
6. Risk (cumulative incidence)
• It is a measure of the occurrence of new cases
• i.e. Proportion of unaffected persons (PAR) in
the population who, will contract the disease
over a specified period of time
New cases
Person at Risk
R =
• Has no unit;
• lies between 0 and 1
7. onset end
A
B
C
D
E
F
Hypothetical study of group of six subjects
1995 96 97 98 99 00 01 02 03 04
Dx …………………………………………Death
97 02
99
97
99 02
Dx…......………..
97
02
What is the Risk of Dis. development within 2 years of enrolment?
New cases
R =
Person at risk
= 1/6 = 0.17 OR 17%
8. Example….
• If 596 patients developed Hosp. Acquired infection
out of 5031 patients admitted in comprehensive
cancer centre
• Estimate a cancer patient’s risk of getting HAI.
• Risk period?
- Starts 48 hrs after hospitalization and ends 48 hrs
after discharge.
New cases
R =
Person at risk
= 596/5031 = 0.12 OR 12%
9. • Can we apply this risk to our patient?
• More likelihood of infection for our patient
can come from studies on similar
subjects…having fever, and low granulocyte
count….
• Now if 1022 such cancer patients were studied
and 530 had HAI then the Risk of HAI is
530/1022 = 0.52 i.e. 52%
10. Measures of Disease Occurrence ctd…
• Prevalence (Burden of Disease)–
indicates number of existing cases of a disease in a
population at a time.
• E.g. An important question in deciding antibiotic use
to the patient is the type and magnitude of infection
anticipated!!
• We know that individuals with low neutrophil count
are susceptible to wide variety of infections…
– S.aureus was cultured from 62 out of 96 patient’s specimens
• Prev. of S.aureus infection = 62/ 96 = 0.65 i.e. 65%
11. onset end
A
B
C
D
E
F
Hypothetical study of group of six subjects
1995 96 97 98 99 00 01 02 03 04
Dx …………………………………………Death
97 02
99
97
99 02
Dx………………
97
02
What is the Prevalence of Disease in 2001?
Total cases
P =
Total population
= 1/4 = 0.25 OR 25%
12. Measures of Disease Occurrence ctd…
• Incidence Rate – measures the rapidity with
which new cases of the disease develop.
• Estimated by observing a population and
counting the number of new cases over Net
Time (person years) i.e.
Incidence Rate = New cases/ Total person time
A subject at risk of disease followed for 1 yr, or
5 yrs contributes 1 or 5 person-years of
observation respectively.
13. onset end
A
B
C
D
E
F
Hypothetical study of group of six subjects
0 1 2 3 4 5 6 7 8 9
Dx …………………………………………Death
97 02
99
97
99 02
Dx,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,
97
02
How many person years are contributed by A, B, C, D E and F?
04
Total new cases
IR=
Total person years
= 2/22 = 0.09 cases /person years
i.e. 9 cases/ 100 person-yrs
04
04
98
Observation years
95
14. Example of HAI ctd…
• Those 5031 remained under observation for a total
of 127859 patient days
• What is the average length of stay?
• Since 596 patients developed HAI the IR would be
– 596/ 127859= 0.0047 cases/ patient days
• Can be expressed for better readability as 4.7
cases/ 1000 patient days
• Interpretation: among patients similar to those
studied, on an average, about 0.47% patient/day
would be expected to develop a HAI (1/200 cases)
127859 / 5031
= 25.41
15. Calculation of IR for a Large Pop.
• Calculating person-years (PT) for each individual
would be too cumbersome! Alternatively
• PT = (Av. Size of PAR) X (Length of observation)
• In many instances, relatively few people develop
the disease and there is no other demographic
shift hence whole Pop. Can be taken as At
Risk…i.e. not excluding patients
16. Calculation of IR for a Large Pop.
• PT = (Size of entire Pop.) X (Length of
observation)
• If there are an estimated 1,91,85,836 women in
an area btw 1996 and 2000 (5 yrs period) and
2957 women were newly diagnosed with Acute
myelocytic leukimia (AML)
• What is the annual incidence rate of AML ?
• 1,91,85,836 women x 5 Yrs = 9,59,29,180 WY
• IR = 2957 new cases/ 9,59,29,180 WY =
3.1cases /1,00,000 WY
17. Characteristic Risk Prevalence Incidence Rate
What is
measured
Probability of
Disease
occurance
Proportion of
Pop. With disease
Rapidity of
Disease
Occurrence
Units None None Cases/ person-
time
Time of
disease Dx
Newly
diagnosed
Existing cases Newly diagnosed
Synonyms Cumulative
Incidence
- Incidence Density
Characteristics of Risk, Prevalence & Incidence Rate
In our Hypothetical Ex. In 2001 Prev. was 25%,
2 Yr. Risk was 17% and the IR was 9 cases/ 100 yrs
18. Problems with Incidence and
Prevalence Measurements
• Problems with Enumerator
– The first problem is defining who has the disease.
– The next issue is Method of data collection – interview, self
reporting , survey… associated biases!!
• Problems with Denominators
– everyone in the group represented by the denominator must
have the potential to enter the group that is represented by
the numerator…
PAR concept
• Problems with Hospital Data
19. Relationship Between Incidence and
Prevalence
• There is an important relationship between
incidence and prevalence: in a steady-state
situation, in which the rates are not changing
and in-migration equals out-migration, the
following equation applies:
• Prevalence = Incidence × Duration of disease
20. Example
• 2,000 persons are screened for tuberculosis,
Using chest x-rays: 1,000 are upper-income
(HIG) individuals and 1,000 are lower-income
(LIG) individuals.
• X-ray findings are positive in 100 of the HIG
and in 60 of the LIG.
• Can we therefore conclude that the risk of
tuberculosis is higher in HIG people than in
LIG people?
22. 20 30 40 50 60 70 80
0
100
200
300
400
20%
15%
10%
5%
0%
Annual
Rate/
100000
Percent
of
total
cases
Breast cancer incidence rates and distribution of cases by age
Age in yrs
The incidence is increasing so dramatically with
age, why are only fewer than 5% of the cases
occurring in the oldest age group of women?
24. Incidence stable but prevalence increasing
indicates:-
24
0
5
10
15
20
25
30
35
40
45
1
9
9
0
1
9
9
3
1
9
9
6
1
9
9
9
Prevalence
Incidence
New Program or
Better Dx Test !!!
•Death is prevented
and Dis is not cured
• Diagnosed more
•Immigration of cases
25. Incidence maintained but prevalence
declining means:-
25
0
5
10
15
20
25
30
35
1
9
9
0
1
9
9
2
1
9
9
4
1
9
9
6
1
9
9
8
incidence
prevalence
New effective drug!
Or Dis. Became more
Virulent/ fatal,
Emigration of cases
26. Survival
• Probability of being alive for a specific length of
time
• For a Chronic Dis. Like cancer, 1 and 5 Year
survival rates are often used as indicator of the
severity of the disease and the prognosis.
• E.g. if 5-Yr survival for active TB is 0.79, it means
that only 79% of patients with active TB survive
at least 5-Yrs after diagnosis
• Survival Newly Dx Pts.– Deaths
Newly Dx Pts.
For a specified time
27. Dx onset end
A
B
C
D
E
F
Hypothetical study of group of six subjects
0 1 2 3 4 5
Observation years
Patients
Censored
Death
Censored
Death
What is the 2 year survival rate?
2 year survival rate = 5/6 = 0.83 i.e. 83%
What is the 2 year Risk of Death?
2 year Risk of Death = 1/6 = 0.17 i.e. 17%
5 yr S If we assume B & E survive all 5 yrs = 5/6= 0.67=83% !
5 yr S If we assume B & E didn’t survive all 5 yrs = 3/6= 0.33=50%! !
28. Methods to account for censored cases
• Life Table analysis
• Kaplan-Meier analysis And Graphs
0 1 2 3 4 5
20
40
60
80
100
0
Survivors
Percent
Years since Dx
47%
68%
58%
? Median Survival Time
50
52%
Editor's Notes
AML also known as acute nonlymphocytic leukemia, tends to occur in later life, with a median age at onset of 65 years, males are at a higher risk than females.
Risk factors include – exposure to ionizing radiation, benzene, certain drugs, and perhaps cigarette smoke, more in Down syndrome
Presents with variety of symptoms – weakness, fatigue, unexplained weight loss, infection, and bleeding.
Physical examination shows pale, have multiple bruises and fever with evidence of localized infection.
Laboratory examination shows – anemia, low platelet counts, and markedly elevated leukocyte counts
Infection and bleeding in these patients is directly related to chemotherapy induced suppression of bone marrow with consequent reduction in the circulating levels of neutrophils and platelets.
In about 50% of these neutropenic patients with fever, an infection cannot be doccumented either clinically or microbiologically but on the basis evidence broad spectrum antibiotics are given
factor influencing prevalence – longer duration of disease, prolonged life span, increased incidence, in - migration of susceptible, in - migration of cases, out migration of healthy, improved dx facilities (since so many factors unrelated to the cause of dis. Determine prev.- prev studies do not provide strong evidence of causality, but a good measure for chronic diseases of slow onset)
Risk – is the probability that individuals in the population will get the disease in specified time period
What is the difference between incidence and prevalence?
Prevalence can be viewed as a snapshot or a slice through the population at a point in time at which we determine who has the disease and who does not. But in so doing, we are not determining when the disease developed. Some individuals may have developed arthritis yesterday, some last week, some last year, and some 10 or 20 years ago. Thus, when we survey a community to estimate the prevalence of a disease, we generally do not take into account the duration of the disease.
Consequently, the numerator of prevalence includes a mix of people with different durations of disease, and as a result we do not have a measure of risk.
If we wish to measure risk, we must use incidence, because in contrast to prevalence, it includes only new cases or events and a specified time period during which those events occurred.
In the medical and public health literature, the word prevalence is often used in two ways:
Point prevalence- Prevalence of the disease at a certain point in time—this is the use of the term prevalence that we have just discussed.
Period prevalence- How many people have had the disease at any point during a certain time period? The time period referred to may be arbitrarily selected, such as a month, a single calendar year, or a 5-year period. Some people may have developed the disease during that period, and others may have had the disease before and died or been cured during that period. The important point is that every person represented by the numerator had the disease at some time during the period specified.
People at Risk Who Are Observed throughout a Defined Time Period
In the first type of denominator for incidence rate, we specify a period of time, and we must know that all of the individuals in the group represented by the denominator have been followed up for that entire period. The choice of time period is arbitrary: We could calculate incidence in 1 week, incidence in 1 month, incidence rate in 1 year, incidence rate in 5 years, and so on. The important point is that whatever time period is used in the calculation must be clearly specified, and all individuals included in the calculation must have been observed (at risk) for the entire period. The incidence rate calculated using a period of time during which all of the individuals in the population are considered to be at risk for the outcome is also called cumulative incidence, which is a measure of risk.
When All People Are Not Observed for the Full Time Period, Person-Time, or Units of Time When Each Person Is Observed is used
Often, however, every individual in the denominator has not been followed for the full time specified for a variety of reasons, including loss to follow-up or death from a cause other than that being studied. When different individuals are observed for different lengths of time, we calculate an incidence rate (also called an incidence density), in which the denominator consists of the sum of the units of time that each individual was at risk and was observed. This is called person-time and is often expressed in terms of person-months or person-years of observation.
Let us consider person-years: One person at risk who is observed for one year = one person-year. One person at risk observed for 5 years = 5 person-years. But 5 people at risk, each of whom is observed for only 1 year, also = 5 person-years.
HAI = documented by cultures
was not incubating on admission
occurred at least 48 hrs after admission
occurred no more than 48 hrs after discharge
Prevalence is an important and useful measure of the burden of disease in a community.
For example, how many people in the community have arthritis? This information might help us to determine, for example, how many clinics are needed, what types of rehabilitation services are needed, and how many and what types of health professionals are needed. Prevalence is therefore valuable for planning health services. When we use prevalence, we also want to make future projections and anticipate the changes that are likely to take place in the disease burden. However, if we want to look at the cause, or etiology, of disease, we must explore the relationship between an exposure and the risk of disease, and to do this, we need incidence rates.
Nevertheless, prevalence data may at times be very useful—they may be suggestive if not confirmatory in studies of the etiology of certain diseases. For example, asthma is a disease of children for which incidence is difficult to measure because the exact time of the beginning of the disease (its inception) is often hard both to define and to ascertain. For this reason, when we are interested in time trends and geographic distribution of asthma, prevalence is the measure most frequently used. Information on prevalence of asthma is often obtained from self-reports such as interviews or questionnaires. Figure 3-15 shows current asthma prevalence in children up to 17 years of age, by state in the United States for 2001–2005. Current asthma prevalence was based on two questions: “Has a doctor or other health professional ever told you that (child's name) had asthma?” and “Does (child's name) still have asthma?” Overall, prevalence was highest in the northeastern states. The explanation for this observation is not entirely clear. Although adverse climate and polluted air may be implicated, other factors may also play a role in the high asthma prevalence in the northeast, such as more complete ascertainment of cases in the medical care system and higher asthma prevalence in Puerto Rican children who are concentrated in this region.
Another example of the value of prevalence data is seen in Figure 3-16 . One of the most significant and challenging public health problems today in the United States and in other developed countries is the dramatically increasing prevalence of obesity. Obesity is associated with significant morbidity and mortality and is a risk factor for diseases such as hypertension, type 2 diabetes, coronary disease, and stroke. In this figure, prevalence of obesity by state is shown for each of four years: 1990, 1995, 2000, and 2005. The trend over time is grim: In 1990, all reporting states reported obesity prevalence data below 15%. By 2005, all but four states had prevalence estimates above 20%; 17 states reported a prevalence of obesity equal to or greater than 25% and three of these states (Louisiana, Mississippi, and West Virginia) reported obesity prevalence over 30%.
average length of stay = 127859/5031=25.41 days
If we would have taken all patient days i.e. not excluding 596 from 127859 IR would be 0.00464 cases / patient day rather than 0.0047 cases / patient day (not much difference)
We have said that incidence is a measure of risk and that prevalence is not, because it does not take into account the duration of the disease.
Ignore the bar graph for the moment, and consider the line curve. The pattern is one of continually increasing incidence with age, with a change in the slope of the curve between ages 45 and 50 years. This change is observed in many countries. It has been suggested that something happens near the time of menopause, and that premenopausal and postmenopausal breast cancer may be different diseases. Note that, even in old age, the incidence or risk of breast cancer continues to rise.
Now let us look at the histogram—the distribution of breast cancer cases by age. If the incidence is increasing so dramatically with age, why are only fewer than 5% of the cases occurring in the oldest age group of women? The answer is that there are very few women alive in that age group, so that even though they have the highest risk of breast cancer, the group is so small that they contribute only a small proportion of the total number of breast cancer cases seen at all ages. The fact that so few cases of breast cancer are seen in this age group has contributed to a false public impression that the risk of breast cancer is low in this group and that mammography is therefore not important in the elderly. This is a serious misperception. The need to change public thinking on this issue is a major public health challenge. We therefore see the importance of recognizing the distinction between the distribution of disease or the proportion of cases, and the incidence rate or risk of the disease.
e.g. rabies
# Disease duration is reduced and it is becoming acute, or
# Disease becoming more fatal
For example, when insulin first became available, what happened to the prevalence of diabetes?
The prevalence increased because diabetes was not cured, but was only controlled. Many patients with diabetes who formerly would have died now survived; therefore, the prevalence increased.
This seeming paradox is often the case with public health programs: a new measure is introduced that enhances survival or detects the
disease in more people, and the net effect is an apparent increase in prevalence. It may be difficult to convince some people that a program is successful if the prevalence of the disease that is the target of the program actually increases. However, this clearly occurs when death is prevented and the disease is not cured. e.g. diabetes
1.Slow recovery, Fatality reduced (potent drugs available, new drugs effective) or,
3.Immigration of cases from other area (for better facility available).
Recovery is becoming rapid, (may be a new drug identified is more effective)
# Disease turns into a more fatal one (because of treatment failure, change in virulence, drug resistance) or,
# Selective emigration of cases (to seek treatment elsewhere)
Observation of each patient begins at time ‘0’ and continues until one of the following outcomes occur: death, survival for 5 yrs, or follow up ceases (the subject is censored) prior to death or completion of a full period of observation
Example: from 1992-1999 only 19% of patients survived for at least 5 yrs from the time of Dx
for persons under 65 yrs of age at Dx 5-yr survival rate = 31% while for persons above 65 yrs it is 4%
So a person of less than 65 yrs, if diagnosed with this disease would be expected to have 1 in 3 chance of surviving 5 yrs from the time of Dx while a person > 65 yrs has only 1 in 25 chance