A cohort study compares groups of individuals who are exposed or unexposed to a certain factor over long periods of time to determine outcomes. The document discusses key aspects of cohort studies including: prospective cohorts follow exposed and unexposed groups into the future while retrospective cohorts look back in time; cohorts are established based on a common characteristic and followed to measure outcomes; advantages are direct risk estimation and studying rare exposures, while disadvantages include large sample sizes and potential for bias.
In this presentation i tried to explain in detail about cohort studies, their types, how to conduct them, their outcomes, and how to calculate sample size of these studies.
Choice of control group in clinical trialsNagendra SR
To describe the general principles involved in choosing a control group for clinical trials intended to demonstrate the efficacy of a treatment and to discuss related trial design and conduct issues.
In this presentation i tried to explain in detail about cohort studies, their types, how to conduct them, their outcomes, and how to calculate sample size of these studies.
Choice of control group in clinical trialsNagendra SR
To describe the general principles involved in choosing a control group for clinical trials intended to demonstrate the efficacy of a treatment and to discuss related trial design and conduct issues.
Table of contents
-Definition of CRF
-What is CRF
-Types & Methods of filling of CRF
-CRF Input team
-CRF Approval team
-Review team
-Facts about CRF
-Purpose of CRF
-CRF Development process & Guidelines
-Elements of CRF
-CRF Design
-CRF completion checklist
-CRF Design tools
-CRF use
-GCP connection
ETHICAL GUIDELINES FOR BIOMEDICAL RESEARCH ON HUMAN PARTICIPANTSjyothibhat21
This presentation highlights the regulations on Ethical requirements for conducting clinical research in India. This is the guiding regulation for the Ethics Committees in India.
The viewers are requested to give their feedback on the utility of the presentation.
Table of contents
-Definition of CRF
-What is CRF
-Types & Methods of filling of CRF
-CRF Input team
-CRF Approval team
-Review team
-Facts about CRF
-Purpose of CRF
-CRF Development process & Guidelines
-Elements of CRF
-CRF Design
-CRF completion checklist
-CRF Design tools
-CRF use
-GCP connection
ETHICAL GUIDELINES FOR BIOMEDICAL RESEARCH ON HUMAN PARTICIPANTSjyothibhat21
This presentation highlights the regulations on Ethical requirements for conducting clinical research in India. This is the guiding regulation for the Ethics Committees in India.
The viewers are requested to give their feedback on the utility of the presentation.
Study Designs Cohort StudiesChapter 7Learning.docxdeanmtaylor1545
Study Designs: Cohort
Studies
Chapter 7
Learning Objectives
• Differentiate cohort studies from other
study designs
• List main characteristics, advantages, and
disadvantages of cohort studies
• Describe three research questions that
lend themselves to cohort studies
• Calculate and interpret a relative risk
• Give three examples of published studies
discussed in this chapter
Temporality
• Temporality refers to the timing of
information about cause and effect.
• Did the information about cause and effect
refer to the same point in time?
• Or, was the information about the cause
garnered before or after the information
about the effect?
Limitations of Other Study
Designs
• Demonstrating temporality is a
difficulty of most observational
studies.
Limitations of Other Study
Designs (cont’d)
• Cross-sectional and case-control study
designs are based on exposure and
disease information that is collected at the
same time.
• Advantage: Efficient for generating and
testing hypotheses.
• Disadvantage: Leads to challenges
regarding interpretation of results.
Limitations of Other Study
Designs (cont’d)
• Cross-sectional studies:
– Present difficulties in distinguishing the
exposures from the outcomes of the disease,
especially if the outcome marker is a
biological or physiological parameter.
Limitations of Other Study
Designs (cont’d)
• Case-control studies:
– Raise concerns that recall of past
exposures differs between cases and
controls.
Limitations of Other Study
Designs (cont’d)
• There has been no actual lapse of time
between measurement of exposure and
disease.
• None of the previous study designs is well
suited for uncommon exposures.
What is a cohort?
• A cohort is defined as a population group,
or subset thereof, that is followed over a
period of time.
• The term cohort is said to originate from
the Latin cohors, which referred to one of
ten divisions of an ancient Roman legion.
What is a cohort? (cont’d)
• Cohort group members experience a
common exposure associated with a
specific setting (e.g., an occupational
cohort or a school cohort) or they share a
non-specific exposure associated with a
general classification (e.g., a birth
cohort—being born in the same year or
era).
Cohort Effect
• The influence of membership in a particular
cohort.
• Example: Tobacco use in the U.S.
– Fewer than 5% of population smoked around the
early 1900s.
– Free cigarettes for WWI troops increased
prevalence of smoking in the population.
– During WWI, age of onset varied greatly; then
people began smoking earlier in life.
– One net effect was a shift in the distribution of the
age of onset of lung cancer.
Cohort Analysis
• The tabulation and analysis of morbidity or
mortality rates in relationship to the ages
of a specific group of people (cohort)
identified at a particular period of time and
followed as they pass thro.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
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
2. Cohort
Studies
• A cohort study is a type of epidemiological
study in which a large group of people with a
common characteristic is followed over time
to find how many reach a certain health
outcome of interest (disease, death, or a
change in health status or behavior).
• A cohort is defined as a group of persons,
usually 100 or more in size, who share a
common characteristic, e.g. smokers,
workers in a lead smelter.
3. Cohort
Studies
• Cohort studies compare an exposed group of
individuals to an unexposed group of
individuals to determine if the outcome of
interest is associated with exposure.
• There are two types of cohort studies:
prospective and retrospective or historical
cohort.
4. Cohort
Studies
• Prospective studies follow a cohort into the
future for a health outcome, while
retrospective studies trace the cohort back in
time for exposure information after the
outcome has occurred.
• Both types of cohort studies are also referred
to as longitudinal or follow-up studies.
5. Establishing
the cohort
• The investigator controls the selection of the cohort.
• The investigator may choose a cohort based on age,
on exposure to a certain working environment, or on
some other common characteristic.
• Cohorts may be selected on the basis of exposures
known at baseline, e.g. smokers vs. nonsmokers.
Alternatively, cohorts may be divided into exposure
categories once baseline measurements of a defined
population are made.
• For example, the Framingham Cardiovascular
Disease Study (CVD) used baseline measurements
to divide the population into categories of CVD risk
factors.
6. Establishing
the cohort
• For instance, an investigator wants to study
whether exposure to military aircraft engine
noise is a risk factor for hearing loss.
• The cohort this investigator would want to
establish should be composed of two groups
of military personnel: one exposed to engine
aircraft noise (the group under study) and the
other unexposed to engine aircraft noise (a
comparison group).
• The unexposed group should be
representative of the exposed group on all
factors except exposure.
7. The cohort
at baseline
• After the cohort of study subjects is
established, their individual exposures of
interest are identified at baseline (through
interviews, bioassays, medical records, etc.).
• Subjects with the outcome of interest at
baseline are excluded. Therefore, all
members of the cohort are at risk of
developing the outcome at the beginning of
observation.
8. The cohort
at baseline
• Following the last example, anyone in the
cohort of military personnel with a specified
hearing loss at baseline would be excluded
from the cohort and would not be followed.
9. Following
the cohort
• The cohort is then followed over time for
new occurrences of the outcome of interest,
in the above example, hearing loss.
• In a prospective, or concurrent, cohort study
baseline exposure is assessed at the
beginning of the study and the cohort is
followed into the future.
• In a retrospective, or historical cohort study,
baseline exposure is assessed at some point
in the past through historical records, e.g.
health records for a cohort of factory workers
may provide exposure and outcome
information up to the present.
10. Following the cohort
Cohort Baseline exposure Follow-up
Prospective Assessed at
beginning of
study
Followed into the
future for outcome
Retrospective Assessed at some
point in the past via
historical records
Outcome has already
occurred and is
assessed via
historical records
11. Following the cohort
• Cohorts are followed over
time to the end of follow-up.
• Occurrence of the outcome of
interest is determined via
interviews with members of
the cohort and/or family
members, or by viewing
health and/or work records to
conclude the study.
The basic design of a cohort study from beginning of the study to end of follow-up. E = exposed, Ē = not exposed, D =
diseased and D = not diseased.
12.
13. Evaluation
of the
results
• During the follow-up period the investigator counts
the number of subjects who develop the outcome of
interest.
• This count becomes the numerator for an incidence
calculation.
• The number of persons at risk at baseline becomes
the denominator for a cumulative incidence (CI)
calculation.
• The CI measures an individual’s risk of developing
the outcome of interest.
14. Evaluation
of the
results
• Two CIs can be compared to provide a cumulative
incidence ratio (CIR), also known as the relative
risk.
• The reference group is a comparable unexposed
cohort.
• The index group is the exposed cohort. The CIR is
computed by dividing the CI in the index group by
the CI in the reference group.
• The CIR gives a relative measure of the increase or
decrease in incidence between the index and
reference groups.
15. Evaluation
of the
results
• As with CI, an incidence rate measure (IR) uses
new occurrences of the outcome as the numerator.
However, in an IR calculation the person-time
(days, months, or years) at risk during follow-up
becomes the denominator.
• Person-time is measured by summing the total time
each member of the cohort was free of the outcome
of interest and thus contributed to person-time at-
risk during the follow-up period.
• The IR measures the rapidity of occurrence of new
disease in the population.
16. Evaluation
of the
results
• Two IRs may also be compared to find the
relative increase or decrease in the rate of
disease occurrence between the exposed and
unexposed groups.
• This relative measure is called the incidence
rate ratio (IRR).
17. Evaluation
of the
results
• Incidence measures between exposed and
unexposed cohorts can also be subtracted
from one another to find the difference
between the two measures.
• This measure is referred to as the rate
difference.
18. Evaluation
of the
results
• Exposure may be a causative risk factor or a
preventive factor in the development of the
outcome of interest.
• When exposure is preventive the CIR or IRR,
depending on which measure is computed,
will be less than one.
19. Advantages
of a cohort
study
• A cohort study allows a direct estimate of
risk (cumulative incidence) and rate of
disease occurrence over time (incidence
rate).
• Cohort studies are an efficient means of
studying rare exposures (e.g. gasoline fumes,
as discussed in next paragraph), in contrast to
case-control studies, which tend to be better
for rare outcomes.
• Cohort studies also allow the investigator to
assess multiple outcomes of a single
exposure.
20. Advantages
of a cohort
study
• A cohort study would be the most efficient means of
studying the effects of long-term exposure to
gasoline fumes.
• The cohort would consist of individuals who are
exposed daily to gasoline fumes (auto mechanics,
gas station attendants, sea crewman on tankers, etc.).
• By studying this group of individuals, the
investigator can better determine the direct effects of
long-term, regular gasoline inhalation. Also, by
conducting a cohort study, an investigator could
determine if gasoline inhalation causes many
different health outcomes (e.g., different types of
cancer and respiratory illnesses).
21. Additional
advantages
of cohort
studies
• Cohort studies establish temporal relationships
between exposure and outcome.
• Exposure clearly precedes the outcome because
the population under study at baseline is free of
the outcome of interest.
• Cohort studies also avoid recall bias (as the
exposure is determined before the outcome,
one's disease state won't affect how accurately
one recalls exposure levels), as well as, survival
bias (duration of disease influencing exposure
measurements). Therefore, cohort studies are the
best observational design in order to establish
cause and effect relationships.
22. Disadvantages
of cohort
studies
• Cohort studies often require large sample sizes, especially
when the outcome is rare, defined as less than 1 event per
1000 person- years (e.g., all specific cancers). Therefore,
cohort studies tend to be expensive and time-consuming.
• When there are losses to follow-up (individuals who
leave the cohort before the end of follow-up) biases may
occur. Thus, individuals who leave the cohort
prematurely may have a different baseline risk than the
members who remain in the cohort throughout the entire
length of follow-up. Therefore, the study may not be
generalizable to the original target population, but only to
those who remained under investigation throughout the
length of the study.
• Also, any differences in the quality of measurement of
exposure or disease between exposed and non-exposed
cohorts may introduce information bias and thereby
distort the results.
23. Self-
evaluation
Q1: An investigator wants to discover whether
or not being overweight in adolescence
increases the risk of cardiovascular mortality
in adulthood.
a. Assuming historical records are available,
would a prospective or retrospective study
be more practical?
b. Who would comprise the investigator's
cohort under study?
c. Who would comprise the investigator's
exposed and unexposed groups in this
cohort?
24. Self-
evaluation
Q2: An investigator conducts a retrospective cohort
study to explore the relationship between
perimenopausal exogenous estrogen use and the risk
of coronary heart disease (CHD). A total of 5000
exposed and 5000 unexposed women are enrolled and
followed for 15 years for the development of
myocardial infarction (MI). A total of 200 estrogen
users and 300 nonusers had MIs.
a. The risk (CI) of a MI among estrogen users is:
b. The risk (CI) of a MI among nonusers of estrogen
is:
c. The relative risk (CIR) for MI is:
d. Based on the results of this study is estrogen use a
e. causative or protective factor for MI?
25. Reference
• Alexander LK, Lopes B, Ricchetti-Masterson
K, Yeatts KB. Cohort Studies. Epidemiologic
Research and Information Center (ERIC)
Notebook. Second Edition. 2015.