Study designs, Epidemiological study design, Types of studiesDr Lipilekha Patnaik
Study design, Epidemiological study designA study design is a specific plan or protocol
for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one.
Study designs, Epidemiological study design, Types of studiesDr Lipilekha Patnaik
Study design, Epidemiological study designA study design is a specific plan or protocol
for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one.
Case-control study is a variety of analytical studies. This is a brief presentation regarding history, design, issues, advantages - disadvantages and examples of Case-control study.
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
Case-control study is a variety of analytical studies. This is a brief presentation regarding history, design, issues, advantages - disadvantages and examples of Case-control study.
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
Excelsior College PBH 321 Page 1 EXPERI MENTAL E.docxgitagrimston
Excelsior College PBH 321
Page 1
EXPERI MENTAL E PIDE MIOLOGICAL STUDIE S
Epidemiologic studies are either observational or experimental. Observational studies, including ecologic,
cross-sectional, cohort, and case-control designs, are considered “natural” experiments, but experimental
studies are considered true experiments. We will spend the next 2 modules discussing these designs.
Before we begin to discuss study designs, we need a brief introduction to a concept that we will spend more
time discussing in later modules -- bias. The definition of bias is:
“Deviation of results or inferences from the truth, or processes leading to such deviation. Any trend in the
collection, analysis, interpretation, publication, or review of data that can lead to conclusions that are
systematically different from the truth.” (Last, J.M., A Dictionary of Epidemiology, 4th ed.)
Epidemiologists are naturally concerned whether the results of an epidemiologic study are biased, since many
important public health decisions are often drawn from epidemiologic research. The severity of the bias, that
is - how much it influences or distorts the results, is related to the study design as well as how information is
analyzed.
Experimental Studies
The defining feature of experimental studies is that the investigator assigns exposure to the study subjects.
Experimental studies most closely resemble controlled laboratory experiments and serve as models for the
conduct of observational studies, thus they are the “gold standard” of epidemiologic research. Experimental
studies have high validity (i.e., less bias), and can identify even very small effects. The most well known type of
experimental study is a randomized trial (sometimes referred to as a randomized controlled trial), where the
investigator randomly assigns exposure to the study subjects. In this type of study, the only expected
difference between the experimental and control groups is the outcome variable being studied.
Experimental designs like the randomized trial can assess both preventive interventions, where a prophylactic
agent is given to healthy or high-risk individual to prevent disease, or can assess effects of therapeutic
treatment, such as those given to diseased individuals to reduce their risk of disease recurrence, or to improve
their survival or quality of life.
Preventive intervention: Does tamoxifen lower the incidence of breast cancer in women with high risk profile
compared to high risk women not given tamoxifen?
Therapeutic intervention: Do combinations of two or three antiretroviral drugs prolong survival of AIDS
patients as well as regimens of single drugs?
The investigator can assign exposures (or allocate interventions) to either individuals or to an entire
community.
Individual-level assignment: Do women with stage I breast cancer given a lumpectomy alone survive as long
without recurrence of disease as women given a lumpec ...
Arogya karnataka a universal health coverage schemeDrSridevi NH
govt of karnataka is the first to launch a UHC scheme followed by a call from WHO. this ppt is on comparision of various programmes which were present before with that of a new programme
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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.
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
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.
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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.
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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
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
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2. Contents
Introduction
Hierarchy of scientific evidence
Indications for cohort study
Elements of a cohort study
Types
Advantages and disadvantages
Summary
References
3. Introduction
Cohort study is a type of analytical study.
Cohort is defined as a group of people who share a
common characteristic or experience within a
defined time period.
4. what is cohort study???
Compare - occurrence of events /outcomes among
groups of people whose exposure status differs
‘naturally’.
5.
6.
7. Indications for cohort study
There is good evidence of association between
exposure and disease.
Exposure is rare, but the incidence of disease
among exposed is high.
When attrition of study population can be minimized.
When ample of funds are available.
8. Elements of cohort study
Defining the study question
Selecting the study population
Measure exposure
Follow up of participants
Ascertaining outcome
Analysis and results
9. Defining the study question
A study question is framed.
Important terms should be defined.
The diagnostic and eligibility criteria of the disease
must be defined beforehand.
10. Selecting the study population
Selection of study subjects.
Selection of comparison groups.
Internal comparison ---Common exposure Ex: smoking, tobacco
chewing etc
External comparison---rare exposure Ex: Industrial chemicals (
different industries), Ionizing radiation
Comparison with general population.
General
population
Special
groups
Select
groups
Exposure
groups
11. Formation of cohort
Cohorts/ subjects selected must be:-
Free from Outcome under study.
Must be equally susceptible for the outcome.
Both the groups should be comparable in respect of
all the possible variables, which may influence the
frequency of outcome.
Must be amenable for follow-up with least possible
attrition.
12. Healthy worker effect
When exposed group is working population and
Comparison group is general population.
Working population is healthier
General population includes- Sick to work.
How to reduce???
• Same workforce – comparison group with different
level of exposure
• Comparison group in different industry
13. External comparison group is general population
people with unhealthy lifestyle refuse to participate
Volunteers as comparison group.
What if not convinced with comparison group????
Two or more comparison group
Industrial chemical and cancer
Exposed is – workers in industry
Unexposed – General population, another industry.
14. Steps
Defining the study question
Selecting the study population
Measure exposure
Follow up of participants
Ascertaining outcome
Analysis and results
15. Measure exposure
Interviewing cohort members
Medical records ,Employment records
Medical examination/diagnostic procedures.
Environmental surveys.
16. Effect of Ionization radiation on workers
Exposed are workers in the unit.
Unexposed are – those residing in vicinity but not working
in unit
Unexposed group is genuinely unexposed to exposure
Accurate measurement- to avoid Misclassification
Exposure status may change during follow up period
Reassess at periodic interval
17. Information bias
Inadequacy of information derived from medical or
other records.
Difference in Quality and extent of information
obtained for exposed and non exposed groups
Limited sensitivity and specificity of the diagnostic
tests involved
Applying tests of differing sensitivities, differentially
to study groups
18. Steps
Defining the study question
Selecting the study population
Measure exposure
Follow up of participants
Ascertaining outcome
Analysis and results
19. Follow up of participants
Periodic medical examination of each member of the
cohort.
Reviewing physician and hospital records
Routine surveillance of death records
Mailed questionnaires, telephone calls, periodic
home visits –preferably all three on an annual basis
Potential weakness.
20. Biases
Lost to follow up due to
Death
change of residence
Migration
withdrawal of occupation
21. How to reduce??
Ensure completeness of follow up – develop
mechanism for that.
Special group of population can be selected.
Contact relatives to collect information.
22. Steps
Defining the study question
Selecting the study population
Measure exposure
Follow up of participants
Ascertaining outcome
Analysis and results
23. Ascertaining outcome
Records:-
Uniformity
completeness
method adopted may differ between time periods.
Interviews/questionnaires:-
Validity
reliability
social desirability.
Direct measurements:-
variations
measurement error.
24. Sources of data for outcomes
Outcome fatal – death certificates
Routine surveillance
Autopsies
Medical Records
Registries
Insurance data
Periodic direct medical examination
25. Bias in assessment of the
outcome
If the investigator who assess outcome is aware of
exposure status of subjects, then the judgment as to
whether the disease developed may be biased by
that knowledge.
Masking the investigator regarding exposure status.
Newer modalities of outcome ascertainment
26. Steps
Defining the study question
Selecting the study population
Measure exposure
Follow up of participants
Ascertaining outcome
Analysis and results
27. Analysis and results
The data is analyzed in terms of :-
1. Incidence rates of outcome among exposed and
non exposed
2. Estimation of risk
relative risk
attributable risk
28. Incidence rates
Estimation of disease incidence rates (λ)
Calculate total number of events observed among all
individuals (D)
Calculate the sum of the individual observation times (Y)
– person years at risk
Calculate λ = D/Y incidence rates
Rate ratio = λ1/ λ0
Rate difference = λ1- λ0
29. Individual’s observation time
starts when subject joins the study
stops when
– Subject develops the disease
– Subject is lost to follow-up
– The follow-up period ends
30.
31. Relative risk
RR= incidence of disease among exposed
incidence of disease among non exposed
It is the direct measure of the strength of association
between suspected cause and effect.
RR=1 indicates no association
RR>1 indicates positive association
RR<1 indicates negative association
34. Population attributable risk
1953- Levin - first described this measure (smoking
& lung Ca)
It gives the measure of disease risk in the total
population associated with the exposure
AR= Iexp – Inonexp
PAR= Ipop – Inonexp
35.
36. PAR estimates the amount by which the disease
could be reduced in the population if suspected
factor is eliminated or modified.
37. Types of cohort study
Prospective cohort study
Retrospective cohort study
Retro-Prospective cohort study
case cohort study
39. Retrospective cohort study
Here outcomes would have occurred before the start
of the investigations
The investigator goes back in time, select the study
groups from the records, and traces them forward
through time up to the present.
Faster, less expensive
Useful for disease with long period between
exposure and outcome
Data on exposure and confounders – may be less
accurate
40. Retro prospective study
Both the retrospective and prospective elements are
combined.
Cohort is identified from past records, and is
followed up prospectively for the assessment of
outcome
43. Advantages
Incidence can be calculated
Several possible outcomes related to exposure can
be studied simultaneously.
Provide a direct estimate of relative risk
Dose response ratio can also be calculated.
Bias can be minimised
PAR can be calculated.
44. Disadvantages
Involve large number of people- unsuitable for
investigating uncommon diseases
It takes long time to complete study and obtain results
Administrative problems are inevitable
Lost to follow up
It is difficult to introduce new knowledge and
technologies.
Expensive
Ethical issues.
Study itself may alter peoples behavior.
45. Summary
Cohort study constitutes the design of reference for all
other designs in observational epidemiology. The
advantage of cohort design is the possibility of studying
the occurrence of several events in addition to that
initially planned.
Cohort studies have proven to be extremely valuable in
many areas of medical research including cardiovascular
disease, cancer, infectious diseases. Data from these
studies is of great use for the development of public
policy, such as treatment guidelines.
46. References
1. Park K. Cohort study . Parks text book of
Preventive and social medicine. 23rd edition.
Jabalpur, M/S Banarsidas Bhanot Publishers.
January 2015 page 75-80
2. Leon Gordis. Cohort studies. Epidemiology 4th
edition. Elsevier. 2009 page 167-176.
3. Roger detels. Oxford textbook of public health. 5th
edition. Oxford 2009 page 508-525
4. Textbook of public health and community medicine
1st edition 2009. AFMC page 147-150
Editor's Notes
You have take a comparable group But not convinced about its comparability Feel some confounding factors are still there