1) Descriptive studies aim to provide data about disease related problems in a community in terms of morbidity and mortality rates. They help formulate etiological hypotheses by observing factors associated with increased disease frequency.
2) Descriptive studies describe variations in disease occurrence by time, place, and person. They provide background data for planning health services.
3) Limitations include the lack of a comparison group, which prevents calculating risk or testing hypotheses. Ecological fallacy can also occur.
Meta-analysis in Epidemiology is:
Useful tool for epidemiological studies which investigates the relationships between certain risk factors and disease.
Useful tool to improve animal well-being and productivity
Despite of a wealth of suitable studies it is relatively underutilized in animal and veterinary science.
Meta-analysis can provide reliable results about diseases occurrence, pattern and impact in livestock.
It is utmost essential to take benefit of this statistical tool for produce. more reliable estimates of concern effects in animal and veterinary science data.
“The study of the distribution and determinants of health-related states or events in specified population and the application of the study to control of health problems.”
Meta-analysis in Epidemiology is:
Useful tool for epidemiological studies which investigates the relationships between certain risk factors and disease.
Useful tool to improve animal well-being and productivity
Despite of a wealth of suitable studies it is relatively underutilized in animal and veterinary science.
Meta-analysis can provide reliable results about diseases occurrence, pattern and impact in livestock.
It is utmost essential to take benefit of this statistical tool for produce. more reliable estimates of concern effects in animal and veterinary science data.
“The study of the distribution and determinants of health-related states or events in specified population and the application of the study to control of health problems.”
Sample size and how to calculate it
- Why sample size is important
- Alpha and beta errors
- Main outcome and Effect size
- Practical examples using Means-Proportions-Correlation- Confidence Interval
A cross-sectional study is a descriptive study in which disease and exposure status are measured simultaneously in a given population.
It measures
the prevalence of health outcomes(also called prevalence study)
or determinants of health,
or both,
In a population at a point in time or over a short period.
When the investigator draws a sample out of the study population of interest and examines all the subjects to detect
those having the disease/outcome
and those not having this disease/outcome of interest.
At the same time, finds out whether or not they have the presence of
the suspected cause (exposure)
(or give a History of such exposure in the past),
is called the Cross-sectional analytic study.
A sample design is a definite plan for obtaining a sample from a given population. Researcher must select/prepare a sample design which should be reliable and appropriate for his research study.
Sample size and how to calculate it
- Why sample size is important
- Alpha and beta errors
- Main outcome and Effect size
- Practical examples using Means-Proportions-Correlation- Confidence Interval
A cross-sectional study is a descriptive study in which disease and exposure status are measured simultaneously in a given population.
It measures
the prevalence of health outcomes(also called prevalence study)
or determinants of health,
or both,
In a population at a point in time or over a short period.
When the investigator draws a sample out of the study population of interest and examines all the subjects to detect
those having the disease/outcome
and those not having this disease/outcome of interest.
At the same time, finds out whether or not they have the presence of
the suspected cause (exposure)
(or give a History of such exposure in the past),
is called the Cross-sectional analytic study.
A sample design is a definite plan for obtaining a sample from a given population. Researcher must select/prepare a sample design which should be reliable and appropriate for his research study.
Basics of Epidemiology and Descriptive epidemiology by Dr. Sonam AggarwalDr. Sonam Aggarwal
Epidemiology is the basic science of Preventive and Social Medicine.
Epidemiology is scientific discipline of public health to study diseases in the community to acquire knowledge for health care of the society. (prevention, control and treatment).
Introduction to Epidemiology
History of Epidemiology.
Definition of Epidemiology and its components.
Epidemiological Basic concepts.
Aims of Epidemiology.
Ten Uses of Epidemiology.
Scope or The Areas of Application .
Types of Epidemiological Studies.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
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Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
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TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
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These lecture slides, by Dr Sidra Arshad, offer a quick overview of 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 leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
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. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
2. Epidemiological Studies
Observational Studies
Descriptive Studies
Case reports
Cross-sectional
Descriptive Studies
Longitunidal
Descriptive studies
Ecological Studies
Analytical
Studies
Cross-sectional Studies
Case-Control studies
Cohort Studies
Experimental /
Interventional Studies
Randomized Control
Trials
Field Trials
Community Trials
3.
4. Types of Descriptive studies
Case Reports and Case Series
1. This type of study is based on reports of a single, or else a series of cases of specific treated or
untreated condition without any specific comparison (control) group.
2. Apart from describing symptoms in series of patients , we may also work out “proportions” (e.g.
percentage of cases that belong to a particular age group, sex, ethnic group etc.).
• However, we must remember that these proportions do not indicate risk since the denominator is still the number of cases
and not the population at risk
Cross Sectional Descriptive Studies
Cross sectional descriptive studies are done on a sample of the total population and may be
community based or hospital based. They are mainly directed to work out the :
1. “Prevalence” of a factor of interest.
2. “Mean” of a factor of interest.
3. Description of a “Pattern” .
4. As a surrogate for longitudinal descriptive studies
5. Longitudinal Descriptive studies
1. More scientific than Cross sectional ones but at the same time more costly and time
consuming.
2. In contrast to a cross sectional descriptive study, a longitudinal descriptive study follows
up a single group of subjects over a defined period of time.
3. General Objectives of Longitudinal Descriptive study:
a) To see the incidence of a disease.
b) To describe the ‘natural history of a disease’.
c) To describe a health related natural phenomena.
d) To study the ‘trend’ of a disease.
e) To study the ‘trend of a health - related phenomena.
A Cross - sectional study gives us the “prevalence” while A Longitudinal study gives us
the “incidence”.
Types of Descriptive studies
6. 1)Defining population to be studied.
Definingdisease under study.
Describing disease by *Time *Place *Person.
Measurement of the disease.
Comparing with known indices.
Formulation of an aetiological hypothesis
1
2
3
4
5
6
7. Defining Population to be studied
Descriptive studies are investigations of populations, not individuals. 1st step hence , is to define the ‘ Population
base’.
he concept of 'defined population' (or population at risk) is crucial in epidemiological studies. It provides the denominator for calculating rates which are essential to measure the frequency of disease and study
its distribution and determinants.
The "defined population" can be the whole population in an area, or a representative sample taken from it.
The defined population needs to be large enough so that age, sex and other specific rates are meaningful.
The community chosen should be stable, without migration into or out of the area.
Community participation is an essential component.
The population chosen , should not be overtly different from other communities in the region.
A health facility should be close enough to provide relatively easy access for patients requiring medical services.
8. Defining the disease under study
Once population to be studied is specified, define disease to be studied.
The needs of clinician & epidemiologist vary while defining the disease.
The epidemiologist needs an "operational definition", by which the condition can be identified and measured
in the defined population with good degree of accuracy.
The diagnostic methods for use in epidemiological studies must be acceptable to the population to be studied,
and applicable to their use in large populations.
With regard to certain diseases (e.g., neurological diseases) which often do not have pathognomonic signs and
symptoms, disease definition is a crucial concern for the epidemiologist. In such cases, the epidemiologist
frames his own definition keeping the objectives of his study in view and aiming at the same time a degree of
accuracy sufficient for his purpose.
Once established, the case definition must be adhered to throughout the study.
9. Describing disease by Time, Place, Person
Person related Variables
• Age
• Sex
• Ethnic group
• Social class
• Occupation
• Education
• Marital Status
• Family variables
• Twin studies
• Other variables
10. Describing disease by Time, Place, Person
According to
Calendar time
Short-term (Epidemic)
fluctuations
Common Source
Propagated
Source
Long-term (Secular)
trends
Changes in disease over a
period of decades
According to natural
time / non-calendar
Seasonal Fluctuation
Cyclic Fluctuation
15. Describing disease by Time, Place, Person
Many diseases have typical spatial relationships. Geographical pathology is an important
dimension of descriptive epidemiology.
Differences in the distribution of a disease according to place may be made according to Political
boundaries or according to Natural boundaries.
Geographic patterns provide an important source of clues about the causes of the disease. The
range of geographic studies include those concerned with local variations.
a) International- National variations
b) Rural –urban variations
c) Local distributions
When making such international comparisons in respect of a disease, one must initially assess
whether these observed differences are artifactual.
We must make sure that the differences are not artifactual, but real, [ either due to the play of
environmental factors or else genetic factors], a good method of dissecting this out are “Migrant
Studies”.
16. Describing disease by Time, Place, Person
Migrant studies can be carried out in two ways :
a) Comparison of disease and death rates for migrants with those of their kin who have stayed
at home.
• If the disease and death rates in migrants are similar to country of adoption over a period of
time, the likely explanation would be change in the environment.
b) Comparison of migrants with local population of the host country.
• We get information on genetically different groups living in a similar environment. If the
migration rates of disease and death are similar to the country of origin, the likely explanation
would be the genetic factors.
Regional Variations within countries : Regional differences help in developing hypothesis
about role of possible environmental agents in the etiology of the disease. Eg : Goitre
. Rural - Urban differences point out towards possible environmental factors; e.g. IHD, STDs,
Hypertension etc. are more common in the urban areas while oro - faecal infections are more
common in rural areas.
17. Describing disease by Time, Place, Person
Local distributions : Most often, the epidemiologists have to study local distributions,
i.e. the differences in disease occurrence according to place within small, defined localities.
For examining such differences, the epidemiologist makes a “spot map” which is a detailed layout map of that
area or locality, showing the accommodation, water sources and supply lines, nightsoil disposal systems, vector
breeding areas, eating establishments and various other environmental factors of relevance.
On the same map, the epidemiologist plots the cases of the disease according to their frequency, looking for the
places where there is a high frequency of cases and then trying to relate them with the possible environmental
factors.
Proper knowledge of use of ‘spot map’ is necessary while investigating most of the epidemic outbreaks
19. Describing disease by Time, Place, Person
Methods of Displaying & Analysing Place related disease:
1. Spot Mapping
2. Map-on-map :
In this technique we combine two maps to bring disease frequencies, plotted as coloured dots, into visual
approximation with other variables like roads, rivers, indices of poverty etc. This technique may also be used
for studying “movement” of a disease in both time and place.
20. 1)Defining population to be studied.
Definingdisease under study.
Describing disease by *Time *Place *Person.
Measurement of the disease.
Comparing with known indices.
Formulation of an aetiological hypothesis
1
2
3
4
5
6
21. Measurement of the disease
Its necessary to have a clear picture of the disease load in the population.
Information about the disease load should be available in terms of morbidity ,mortality &
disability.
Measurement of mortality is straightforward.
Morbidity has 2 aspects : incidence & prevalence. Incidence can be obtained from ‘longitudinal
studies’ & prevalence from ‘cross-sectional studies’.
Descriptive epidemiology thus uses a cross-sectional or longitudinal design to estimate
magnitude of health and disease problems in human populations.
22. Measurement of the disease
CROSS-SECTIONAL STUDY : [a.k.a Prevalance study]
Simplest form of observational study.
Single examination of a cross-section of the population at 1 point in time: results of which are
projected on whole population.
More useful for chronic , than short lived study.
A cross-sectional study provides information about disease prevalence, but not enough
information about the natural history of disease or about the rate of occurrence of new cases
(incidence).
LONGITUDINAL STUDY :[a.k.a Incidence study ]
23. Comparing with known indices
The essence of epidemiology is to make comparisons and ask questions.
Comparisons between different populations, and subgroups of the same population, give clues to disease
aetiology.
We can also identify or define groups which are at increased risk for certain diseases.
24. Formulation of a Hypothesis
A hypothesis is a supposition, arrived at from observation or reflection.
It can be accepted or rejected, using the techniques of analytical epidemiology.
An epidemiological hypothesis should specify the following:
1. The population - the characteristics of the persons to whom the hypothesis applies
2. The specific cause being considered .
3. The expected outcome - the disease .
4. The dose-response relationship - the amount of the cause needed to lead to a stated
incidence of the effect
5. The time-response relationship - the time period that will elapse between exposure to the
cause and observation of the effect.
The success or failure of a research project frequently depends upon the soundness of the
hypothesis
25. 1) Provide data about the types of disease related problems in the community in terms of
morbidity and mortality rates.
2) Help in the formulation of an etiological hypothesis.
i.e, the existence of a possible causal association between a factor and a disease is usually
recognized in descriptive studies. Thus, if the disease is observed to be more frequent in a
particular group than in others, hypotheses are formulated to explain the increased frequency
3) Provide background data for planning, organizing and evaluating preventive and curative
services.
4) Contribute to research by describing variations in disease occurrence by time , place and
person
26. 1) Since there is no information of the population at risk , nor a comparison group, neither can risk be
calculated nor can a hypothesis be tested
2) Ecological fallacy
27. Difference between Descriptive & Analytical study
SL.No DESCRIPTIVE STUDY ANALYTICAL STUDY
1. Only one group is studied At least 2 groups are studied to draw comparisions.
2. Before the study , there is no explicit
hyposthesis regarding cause-effect
relationship.
At the start of the study ,there is a definite
hypothesis , regarding an exposure possibly
causing an outcome
3. The study ends with development of
possible hyposthesis regarding cause and
effect relationship .
At the end of study , we confirm or reject the
hypothesis with which the study was started.
28. Thank You
References
Park, K., 2018. Parks Textbook Of Preventive In Social Medicine. 24th
ed. P47 - 51 Jabalpur: Banarsidas Bhanot Publishers.
Rajvir Balwar , 2009. Textbook of Public Health and Community
Medicine. 1st ed. P. 23 -25 Pune: Armed Forces Medical College and
WHO (collaboration).