This document discusses various study designs used in epidemiology. It begins by describing components of epidemiology such as measuring disease frequency and distribution. It then discusses the need for research designs and classifies epidemiological research into descriptive and analytical studies. Descriptive studies like case reports and cross-sectional studies are used to describe diseases. Analytical studies, including observational cohort and case-control studies as well as experimental designs, are used to test hypotheses. The document focuses on cohort studies, outlining the steps involved such as selecting exposed and non-exposed groups, defining and measuring exposures, following up to assess outcomes, and analyzing results.
What is Cohort?
Indication and Elements of Cohort Study.
What is Relative risk and Attributable risk, and its interpretation?
Advantages & disadvantages of Cohort study.
Difference between Case control & Cohort study.
cohort study is clinical study design. particular form of longitudinal study that samples a cohort group of people. type of panel study.
cohort study represent fundamental designs of epidemiology in field of medicine, social science & psychology.
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.
An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called study and control groups to receive and not receive an experimental preventive or therapetuic procedure, maneuver, or intervention .
What is Cohort?
Indication and Elements of Cohort Study.
What is Relative risk and Attributable risk, and its interpretation?
Advantages & disadvantages of Cohort study.
Difference between Case control & Cohort study.
cohort study is clinical study design. particular form of longitudinal study that samples a cohort group of people. type of panel study.
cohort study represent fundamental designs of epidemiology in field of medicine, social science & psychology.
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.
An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called study and control groups to receive and not receive an experimental preventive or therapetuic procedure, maneuver, or intervention .
Coronary restenosis refers to the re-narrowing or reoccurrence of blockage in a coronary artery that has previously been treated with a procedure such as angioplasty and stent placement. Angioplasty is a procedure used to open narrowed or blocked arteries by inflating a balloon-like device to widen the artery, and a stent may be placed to help keep the artery open.
Restenosis can occur when the artery becomes narrowed again due to various factors, including the growth of scar tissue inside the artery, inflammation, or the formation of new plaque. Restenosis can lead to recurrent symptoms of chest pain (angina) or other complications.
To help prevent restenosis, doctors may recommend lifestyle changes such as quitting smoking, adopting a heart-healthy diet, exercising regularly, and taking medications to manage risk factors such as high cholesterol, high blood pressure, and diabetes. In some cases, additional treatments or procedures may be necessary to address restenosis, such as repeat angioplasty, stent placement, or bypass surgery. It's essential for individuals who have undergone coronary artery procedures to follow their healthcare provider's recommendations for monitoring and managing their heart health to reduce the risk of restenosis.
Arrhythmias are abnormal heart rhythms that can occur when the electrical impulses that coordinate the heartbeats are disrupted. There are different types of arrhythmias, including:
1. Atrial Fibrillation (AFib): This is the most common type of arrhythmia and occurs when the heart's upper chambers (atria) beat irregularly and out of sync with the lower chambers (ventricles).
2. Supraventricular Tachycardia (SVT): SVT is a fast heart rate originating above the ventricles, often in the atria.
3. Ventricular Tachycardia (VT): VT is a fast heart rate that starts in the heart's lower chambers (ventricles).
4. Ventricular Fibrillation (VFib): VFib is a life-threatening arrhythmia where the ventricles quiver instead of pumping blood effectively.
5. Bradycardia: This is a slow heart rate, usually below 60 beats per minute.
Arrhythmias can be caused by various factors, including heart disease, high blood pressure, diabetes, smoking, excessive alcohol consumption, stress, certain medications, and structural abnormalities in the heart. Some arrhythmias may not cause any symptoms, while others can lead to symptoms such as palpitations, dizziness, chest pain, shortness of breath, and fainting.
Treatment for arrhythmias depends on the type and severity of the condition. It may include lifestyle modifications, medications, medical procedures like cardioversion or ablation, or implantation of devices like pacemakers or implantable cardioverter-defibrillators (ICDs) to help regulate the heart's rhythm.
If you experience symptoms of an arrhythmia or have been diagnosed with one, it's important to work closely with your healthcare provider to determine the best treatment plan and management strategies to help control
Unit 2. Introduction to Quantitative & Qualitative Reseaerch.pptxshakirRahman10
Introduction to Quantitative and Qualitative Research:
Objectives:
Define the terms of qualitative and quantitative research.
2. Differentiate between qualitative and quantitative research.
3. Describe methods/approaches/types of quantitative research, i.e. Descriptive, Co- relational, Quasi-Experimental and Experimental research.
4. Describe methods/approaches/types of qualitative research i.e. Phenomenological, Grounded Theory, Ethnographical, and Historical research
5. Understand methodologies of qualitative and quantitative research.
Quantitative Research:
Attempts to explain phenomena by collecting and analyzing numerical data
Tells if there is a “difference” but not necessarily why
Data collected are always numerical and analysed using statistical methods
Variables are controlled as much as possible (RCTs as the gold standard) so could eliminate interference and measure the effect of any change
Randomisation to reduce subjective bias
If there are no numbers involved, its not quantitative
Some types of research lend themselves better to quant approaches than others.
Quantitative data:
Data sources include
Surveys where there are a large number of respondents (esp where you have used a Likert scale)
Questionnaires, data collection tools/ instruments
Observations (counts of numbers and/or coding data into numbers)
Secondary data (government data; SATs scores etc)
Analysis techniques include hypothesis testing, correlations and cluster analysis.
Qualitative Research:
Any research that doesn’t involve numerical data
Instead uses observations, words, pictures, videos, audio recordings. Field notes, expressions, and peoples’ own words.
Tends to start with a broad question rather than a specific hypothesis
Develop theory rather than start with one
Tends to yield rich data to explore how and why things happened
Don’t need large sample sizes (in comparison to quantitative research).
Qualitative data:
Interviews (structured, semi-structured or unstructured)
Focus groups
Questionnaires or surveys
Secondary data, including diaries, self-reporting, written accounts of past events/archive data and company reports;
Direct observations – may also be recorded (video/audio)
Ethnography
Data analysis; thematic or content analysis .
Descriptive Studies:
Describe only; do NOT examine associations between Exposure (E) and health Outcome (O).
Generally the purpose is to describe the variability in a health outcome and/or formulate hypotheses.
A descriptive study involves describing the characteristics of a particular situation event or case.
Descriptive studies can be carried out on a small or larger scale.
Case Study :
A study of one diseased individual, providing a detailed description of an uncommon disease; provides timely or rare information.
Case Series :
A study of multiple occurrences of unusual cases that have similar characteristics.
Investigators can calculate the frequency of symptoms or characteristics of people with the disease.
Diseases that are spread by arthropod or small animal vectors.
Vectors act as the main mode of transmission of infection from one host to another, & as such form an essential stage in the transmission cycle.
Zoonoses : are infections which are naturally transmitted between vertebrate animals and people.
The term zoonosis'Derived from the Greek
ZOON (animals) and NOSES (diseases)
People, animals, birds, arthropods and the inanimate environment are all involved in cycles of zoonotic infection
There is no specific format But every institute have their own guideline and instructions,
In preparing Synopsis you should restrict the size of your research area in line with the length of dissertation/Research paper/Theses required by College/University
Screening is the testing of apparently healthy populations to identify previously undiagnosed diseases or people at high risk of developing a disease.
Screening aims to detect early disease before it becomes symptomatic.
Screening is an important aspect of prevention, but not all diseases are suitable for screening.
Lecture for Post and Undergraduate.
From the past two decades Non Communicable diseases are increasing in both developing and developed countries due to which developing are experiencing double burden of diseases.
CHAPTER 1 SEMESTER V - ROLE OF PEADIATRIC NURSE.pdfSachin Sharma
Pediatric nurses play a vital role in the health and well-being of children. Their responsibilities are wide-ranging, and their objectives can be categorized into several key areas:
1. Direct Patient Care:
Objective: Provide comprehensive and compassionate care to infants, children, and adolescents in various healthcare settings (hospitals, clinics, etc.).
This includes tasks like:
Monitoring vital signs and physical condition.
Administering medications and treatments.
Performing procedures as directed by doctors.
Assisting with daily living activities (bathing, feeding).
Providing emotional support and pain management.
2. Health Promotion and Education:
Objective: Promote healthy behaviors and educate children, families, and communities about preventive healthcare.
This includes tasks like:
Administering vaccinations.
Providing education on nutrition, hygiene, and development.
Offering breastfeeding and childbirth support.
Counseling families on safety and injury prevention.
3. Collaboration and Advocacy:
Objective: Collaborate effectively with doctors, social workers, therapists, and other healthcare professionals to ensure coordinated care for children.
Objective: Advocate for the rights and best interests of their patients, especially when children cannot speak for themselves.
This includes tasks like:
Communicating effectively with healthcare teams.
Identifying and addressing potential risks to child welfare.
Educating families about their child's condition and treatment options.
4. Professional Development and Research:
Objective: Stay up-to-date on the latest advancements in pediatric healthcare through continuing education and research.
Objective: Contribute to improving the quality of care for children by participating in research initiatives.
This includes tasks like:
Attending workshops and conferences on pediatric nursing.
Participating in clinical trials related to child health.
Implementing evidence-based practices into their daily routines.
By fulfilling these objectives, pediatric nurses play a crucial role in ensuring the optimal health and well-being of children throughout all stages of their development.
One of the most developed cities of India, the city of Chennai is the capital of Tamilnadu and many people from different parts of India come here to earn their bread and butter. Being a metropolitan, the city is filled with towering building and beaches but the sad part as with almost every Indian city
Struggling with intense fears that disrupt your life? At Renew Life Hypnosis, we offer specialized hypnosis to overcome fear. Phobias are exaggerated fears, often stemming from past traumas or learned behaviors. Hypnotherapy addresses these deep-seated fears by accessing the subconscious mind, helping you change your reactions to phobic triggers. Our expert therapists guide you into a state of deep relaxation, allowing you to transform your responses and reduce anxiety. Experience increased confidence and freedom from phobias with our personalized approach. Ready to live a fear-free life? Visit us at Renew Life Hypnosis..
India Clinical Trials Market: Industry Size and Growth Trends [2030] Analyzed...Kumar Satyam
According to TechSci Research report, "India Clinical Trials Market- By Region, Competition, Forecast & Opportunities, 2030F," the India Clinical Trials Market was valued at USD 2.05 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 8.64% through 2030. The market is driven by a variety of factors, making India an attractive destination for pharmaceutical companies and researchers. India's vast and diverse patient population, cost-effective operational environment, and a large pool of skilled medical professionals contribute significantly to the market's growth. Additionally, increasing government support in streamlining regulations and the growing prevalence of lifestyle diseases further propel the clinical trials market.
Growing Prevalence of Lifestyle Diseases
The rising incidence of lifestyle diseases such as diabetes, cardiovascular diseases, and cancer is a major trend driving the clinical trials market in India. These conditions necessitate the development and testing of new treatment methods, creating a robust demand for clinical trials. The increasing burden of these diseases highlights the need for innovative therapies and underscores the importance of India as a key player in global clinical research.
R3 Stem Cells and Kidney Repair A New Horizon in Nephrology.pptxR3 Stem Cell
R3 Stem Cells and Kidney Repair: A New Horizon in Nephrology" explores groundbreaking advancements in the use of R3 stem cells for kidney disease treatment. This insightful piece delves into the potential of these cells to regenerate damaged kidney tissue, offering new hope for patients and reshaping the future of nephrology.
CRISPR-Cas9, a revolutionary gene-editing tool, holds immense potential to reshape medicine, agriculture, and our understanding of life. But like any powerful tool, it comes with ethical considerations.
Unveiling CRISPR: This naturally occurring bacterial defense system (crRNA & Cas9 protein) fights viruses. Scientists repurposed it for precise gene editing (correction, deletion, insertion) by targeting specific DNA sequences.
The Promise: CRISPR offers exciting possibilities:
Gene Therapy: Correcting genetic diseases like cystic fibrosis.
Agriculture: Engineering crops resistant to pests and harsh environments.
Research: Studying gene function to unlock new knowledge.
The Peril: Ethical concerns demand attention:
Off-target Effects: Unintended DNA edits can have unforeseen consequences.
Eugenics: Misusing CRISPR for designer babies raises social and ethical questions.
Equity: High costs could limit access to this potentially life-saving technology.
The Path Forward: Responsible development is crucial:
International Collaboration: Clear guidelines are needed for research and human trials.
Public Education: Open discussions ensure informed decisions about CRISPR.
Prioritize Safety and Ethics: Safety and ethical principles must be paramount.
CRISPR offers a powerful tool for a better future, but responsible development and addressing ethical concerns are essential. By prioritizing safety, fostering open dialogue, and ensuring equitable access, we can harness CRISPR's power for the benefit of all. (2998 characters)
CHAPTER 1 SEMESTER V PREVENTIVE-PEDIATRICS.pdfSachin Sharma
This content provides an overview of preventive pediatrics. It defines preventive pediatrics as preventing disease and promoting children's physical, mental, and social well-being to achieve positive health. It discusses antenatal, postnatal, and social preventive pediatrics. It also covers various child health programs like immunization, breastfeeding, ICDS, and the roles of organizations like WHO, UNICEF, and nurses in preventive pediatrics.
Epidemiological study Design Case Control And Cohort Study.ppt
1. MBBS.USMLE, DPH, Dip-Card, M.Phil, FCPS
Professor Community Medicine
Gujranwala Medical College Gujranwala
Ex-Professor Community Medicine
UmulQurrah University Makka/King Khalid
University Saudi Arabia
DR Muhammad Tauseef Javed
5/31/2023 1
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Study designs in
epidemiology
3. Components of Epidemiology
Measure disease frequency
Quantify disease
Assess distribution of disease
Who is getting disease?
Where is disease occurring?
When is disease occurring?
Formulation of hypotheses concerning causal
and preventive factors
Identify determinants of disease
Hypotheses are tested using epidemiologic
studies
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Why we need research design
Classification of epidemiological
research and study designs
Characteristics of each study design
Choosing appropriate study design for
research title under consideration
What will you learn in this
session?
6. Big Picture
To prevent and control disease
In a coordinated plan, look to
identify hypotheses on what is
related to disease and may be
causing it
formally test these hypotheses
• Study designs direct how the
investigation is conducted
7. Study design: Definition
A 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.
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Study design
A set of defined steps required to
carry out research on a problem
under study. The design will define:
How study subject are selected?
Method of sample size estimation
Procedure of data collection
Procedure of data analysis
Types of statistical test required
9. Comparison (I)
Qualitative
Understanding
Interview/observation
Discovering frameworks
Textual (words)
Theory generating
Quality of informant more
important than sample size
Subjective
Embedded knowledge
Models of analysis: fidelity
to text or words of
interviewees
Quantitative
Prediction
Survey/questionnaires
Existing frameworks
Numerical
Theory testing (experimental)
Sample size core issue in
reliability of data
Objective
Public
Model of analysis:parametric,
non-parametric
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Classification of Epidemiological
Research
Descriptive
Research
Analytic
Research
Observational
Analytic Studies
Experimental
Analytic Studies
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Objectives at various levels
DESCRIPTIVE STUDIES
1. Knowing the frequency of disease
2. Knowing the distribution
3. Developing the hypothesis
OBSERVATIONAL
ANALYTICAL
1. Testing the hypothesis
2. Establishing association
EXPERIMENTAL OR
INTERVENTIONAL STUDIES
1. Strengthening association
2. Establishing the cause
Study Types Objectives
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Design Strategies in Epidemiological
Research
DESCRIPTIVE STUDIES
1. Cross-sectional studies
2. Population Correlations
3. Case reports
OBSERVATIONAL
ANALYTICAL
1. Cross-sectional studies
2. Case control study designs
3. Cohort study design
EXPERIMENTAL OR
INTERVENTIONAL STUDIES
1. Therapeutic or drug trials
2. Preventive trials
Classification Study designs
15. Timeframe of Studies
Prospective Study - looks forward,
looks to the future, examines future
events, follows a condition,
concern or disease into the future
time
Study begins here
16. Timeframe of Studies
Retrospective Study - “to look
back”, looks back in time to study
events that have already occurred
time
Study begins here
17. Study Design Sequence
Case reports Case series
Descriptive
epidemiology
Analytic
epidemiology
Clinical
trials
Animal
study
Lab
study
Cohort Case-
control
Cross-
sectional
Hypothesis formation
Hypothesis testing
18. Descriptive Studies
Case-control Studies
Cohort Studies
Develop
hypothesis
Investigate it’s
relationship to
outcomes
Define it’s meaning
with exposures
Clinical trials
Test link
experimentally
Increasing
Knowledge
of
Disease/Exposure
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Assessment of disease profile
among the school children
Study of Immunization Status in
children under 5 years
Evaluation of blood glucose and
cholesterol levels in obese
Prevalence of hepatitis B and C
among in high risk groups
Descriptive study statements
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1. Defining the problem under study
2. Defining the population under study
(Concept of denominator)
3. Taking the sample of population
4. Collecting the Data
5. Analyzing interpretation of data
6. Drawing the conclusion
7. Generation of hypothesis
Steps for descriptive research
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1. Theoretical definitions
2. Clinical definitions
3. Provisional diagnosis
4. Laboratory diagnosis
What are Operational Definitions
What is the case definition of tuberculosis?
What is the case definition of Hepatitis B?
Defining the problem under
study
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Defining the population under study
Geographical bound population
Age specific population
Disease specific population
Occupation specific population
Hospitalized patients
Vaccinated un-vaccinated
Male or Female population
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Data Collection Procedure
1. Development of data collection
forms or questionnaire
2. Interview
3. Recording observation /clinical
examinations
4. Examination of records
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Primary and Secondary Data
Data specifically collected for the
problem under study is primary data
Using already collected data or other
data sources for research purpose
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Primary Data
Merits Demerits
1. Data forms are objectively
designed
2. No chances of missing
information's
3. Data is uniform
4. Data is easy to analyze
5. Data is valid hence
research is valid
1. Data is not readily
available
2. Cost and logistics
3. Data collection is time-
consuming
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Secondary Data Sources
Census data
Birth and death records
Clinical records
Employment records
HMIS data
Surveys
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Secondary Data
Merits Demerits
1. Readily available data
2. Saving of time in data
collection
3. Saving the cost of data
collection
1. Data is not objectively
collected
2. Required information may
be missing
3. Data is not uniform
4. Poor quality data
5. Difficult to analyze
6. Data is less valid hence
research is less valid
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Data Analysis
Finding the frequency
Finding the percentages
Tabulation
Graphical presentation
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Frequency Distribution
Scabies Frequency Percentage
Urban 20 20.00
Slums 56 56.00
Rural 24 24.00
Total 100 100.00%
Dr. M. Ashraf Majrooh
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Arranging the data by person,place
and time
Frequency among male & female
Frequency among white & black
Frequency among rural & urban
Frequency in Asia & Europe
Frequency in winter & summer
Month-wise frequencies
Year-wise frequencies
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Drawing the conclusion
Frequency is more in male than
female
Frequency is more in urban or rural
Frequency is more in winter than
summer
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Hypothesis Formulation
Method of difference
Difference of frequencies in two sets of
circumstances
Method of agreement
A single factor is common in number
circumstances in which disease occurs
with high frequencies
Method of Concomitant variations
Frequency of factor varies with frequency of
disease
33. Case Reports
Detailed presentation of a single
case or handful of cases
Generally report a new or unique
finding
e.g. previous undescribed disease
e.g. unexpected link between
diseases
e.g. unexpected new therapeutic
effect
34. Case Series
Experience of a group of patients
with a similar diagnosis
Assesses prevalent disease
Cases may be identified from a
single or multiple sources
Generally report on new/unique
condition
May be only realistic design for rare
disorders
35. Case Series
Advantages
Useful for hypothesis generation
Informative for very rare disease with
few established risk factors
Characterizes averages for disorder
Disadvantages
Cannot study cause and effect
relationships
Cannot assess disease frequency
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The population is examined in single point of time
or it is snap-short of the situation
Both the exposure and the disease are assessed
at the same time
Population as whole or representative sample of
the population is studied
The studies are unable to explain the time
association of the disease
These studies are less time consuming as
compared to longitudinal studies
Important cross-sectional surveys in Pakistan
were, PIHS, MICS, PDS etc.
Salient features of cross-
sectional studies
39. Analytical Research
Observational Analytical
Research
Experimental / Interventional
Analytical Research
Investigator simply observe
the effects of natural exposures
among the study subjects
(Used for hypothesis testing)
Investigator himself do some
intervention and analyze the
effects among study subjects
(Used for hypothesis testing)
Cohort Studies
Case Control Studies
Clinical interventional
Interventional studies
Preventive interventional
studies
5/31/2023 39
DR M TAUSEEF JAVED
40. Study Designs -
Analytic Epidemiology
Experimental Studies
Randomized controlled clinical trials
Community trials
Observational Studies
Group data
Ecologic
Individual data
Cross-sectional
Cohort
Case-control
Case-crossover
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Observational Analytic
Study Designs
1. Cohort Study design
2. Case Control Study design
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What is cohort?
A group of people sharing a common
event or characteristic
The name of the cohort is given on the
basis of event the people share
Birth cohort
Enrolment cohort
Atomic explosion cohort
Occupational cohorts
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Consider the following
statements
Hypertension is more common
among the obese persons?
Physical activity is protective factor
against CHD?
Ionizing radiation causes blood
cancer, infertility, congenital
anomalies?
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Cohort Study design
Compare
Non Exposed
group
Disease Present
Disease absent
Exposed group
Disease Present
Disease absent
Select
Cohort study proceed from cause to the effect
Follow up
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Steps of Cohort Study
1. Selection of exposed population
2. Selection of comparison group
3. Defining and measuring of
exposure
4. Follow-up of both groups
5. Assessment of outcome (Effects)
6. Analysis
7. Scope and limitations
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Selection of Exposed
Population
What do you mean by exposure?
Give some examples of exposures?
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Exposure Groups
Same population is segregated between
exposed and non exposed groups
♣ Smokers and non-smokers
♣ Diabetic verses non- diabetic
♣ Active verses sedentary workers
♣ Special exposure groups
♣ Rubber processing
♣ Uranium mining, coal-mining
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Exposure Groups
Comparison within the same population
with different levels of exposures
Non-smokers
Casual smokers
Regular smokers
Chain smokers
Multiple Comparison groups
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Sources of exposure
information
Information from records
Interview of cohort members
Medical examination
Biochemical assessment
Information and measurement from
environment
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Categorization of exposure
status
Length of employment e.g. 5,10,15, years
Numbers of cigarette per day
Distance from the source
Biological levels of exposure, cholesterol
level, blood sugar level, blood pressure
Environmental levels, Chemical levels,
Radiation levels
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Assessment and measurement of
outcome or effect of exposure
Effect with fatal
outcome
Medical certificate
Hospital records
Physician autopsy
Visual certainty
Postmortem
Non-fatal outcome
Physician records
Hospital records
Discharge certificates
Special registrations
Pathological reports
Periodic medical
examination of cohort
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Analysis of Cohort study
♣ Disease Rate or Incidence among the exposed
♣ Disease Rate or Incidence among the non-
exposed
RELATIVE RISK (Risk Ratio)
Incidence of disease among the exposed
(having the risk factor)
Incidence among the non-exposed
(not having the risk factor)
Relative Risk =
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Interpretation of Relative Risk
What do you understand by RR= 1 ?
What do you understand by RR= 3 ?
What is your opinion if RR is less
than 1
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Scope of cohort study design
It is important to study the rare exposures
Can examine multiple effect of a single
exposure
Can elucidate time relationship between
exposure and the disease
Allows direct measurement of incidence of
disease in exposed and non-exposed
group
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Limitations
Is inefficient design for evaluation of
rare diseases
If prospective it is extremely
expensive and time consuming
If retrospective it requires the
availability of adequate records
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Case Control Study design
Non-diseased
Exposure Present
Exposure absent
Diseased
Exposure Present
Exposure absent
Compare
Case control study proceed from effect to the cause
Select
Trace back
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Case Control Study Steps
1. Definition of cases
2. Selection of cases
3. Selection of Controls
4. Ascertainment of exposure status
5. Analysis
6. Conclusion and interpretation
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Defining the cases
How will you define poliomyelitis?
What is acute flaccid paralysis (AFP)
Is AFP is Poliomyelitis
What is WHO Criteria of
poliomyelitis?
Case definition of Tuberculosis
Cases should be representative of all
diseased
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Selection of Cases
Preferably new cases or incident
cases
Prevalent cases (cases already
present)
Random selection
Convenient selection
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Control
Control must be Ideally matching
with the cases by age, sex and other
characteristics except the control
must not be suffering from diseases
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Criteria for control
Marching by all respect with cases
except not having disease
Hospital controls
Neighborhoods controls
Friends and relatives
Controls from general population
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Methods of selection of control
Random Selection
Convenient Selection
What should be the ratio between
cases and control?
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Ascertainment of Exposure
1. Setting the criteria for exposure
2. Methods of measuring the
exposures
a) Observation
b) Interviews
c) Questionnaire
d) Examination of records
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Analysis
1. Exposure Rates among the
disease (Cases)
2. Exposure Rates among the non-
disease (Control)
3. Odd’s Ratio
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Limitations
Is an inefficient design for evaluation
of rare exposure
Incidence rate cannot be computed
Time relationship cannot be
estimated
This study design is more prone to
bias
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Scope of case control study design
It is quick and inexpensive as
compared to other analytic study
designs
It is particularly suitable for evaluation
of diseases with long latent periods
It is optimum design for rare diseases
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Experimental Analytic Studies
Experimental analytic are exposure
based and the exposure is introduced
by the Investigator
Objectives
Scientific proof of etiological or risk factor
Effectiveness/ efficacy of drugs, vaccine and
health services
Completion of natural history of disease
68. 5/31/2023 DR M TAUSEEF JAVED 68
Experimental analytic
research
Randomized
Control Trials
1. Non-randomized
Trials
2. Uncontrolled
Trials
Can you give example of randomized control and
non-randomized trials?
69. 5/31/2023 DR M TAUSEEF JAVED 69
Steps of experimental /
interventional research
1. Drawing a study protocol
2. Selection of Reference population
3. Selection of Study population
4. Randomization
5. Intervention or Manipulating
6. Follow up
7. Assessment of Outcome
8. Analysis and interpretation of results
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Research protocol?
A lay down procedure for conduction of
study it addresses the
Design issues
Inclusion criteria and exclusion criteria
Blinding (Single, double, or triple blinding)
Outcome criteria
Duration of follow-up
Ethical issues
Dr. M Ashraf Majrooh
71. 5/31/2023 DR M TAUSEEF JAVED 71
Reference population?
The population to which the results
of the study are to be applied
All human being if study is
universally applicable
Geographically bound population
Age specific population
Gender specific population
Other characteristics
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Study population?
The selected individuals which are
actually enrolled for experimental
study
Eligible population
Eligible but not willing for participation
Eligible and willing for participation
If you lay down some inclusion criteria, the cases
fulfilling that criteria will be eligible
The subject who give consent are the willing subjects
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Experimental population
potentially eligible
Unwilling
Completed screening Ineligible
Reference Population
Study subjects
(Willing and eligible)
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Grouping and Randomization
1. Experimental Group
2. Control Group
Interventions/treatments are assigned
randomly
Every individual in study population has the
equal probability to go in to experimental and
control groups is the Randomization
Step-4
75. Experimental population
potentially eligible Unwilling
Completed screening Ineligible
Willing and eligible
participants
Reference Population
Control
Group
Experimental
Group
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DR M TAUSEEF JAVED
76. 5/31/2023 DR M TAUSEEF JAVED 76
Study Population
Control
Group
Experimental
Group
Is it Randomization?
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Randomization
Study Population
Control
Group
Experimental
Group
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Advantages of randomization
To provide the comparability by age sex
and other characteristics
Prevent potential bias from investigator
side
Confounding variables are equally
distributed
Give more authenticity to study
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What is intervention or
manipulation?
Clinical Trials
Preventive Trials
Behavioral modification or risk
factor trials
Cessation Trials
80. 5/31/2023 DR M TAUSEEF JAVED 80
Follow up and compliance
By history and clinical examinations
Disputable outcomes (Subjective
symptoms) relief of pain,
Non-disputably out comes
(Systemic findings)
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Ascertainment of outcome
Positive outcome
If we are looking for beneficial outcome of
and intervention
Negative Outcome
If we are looking for adverse effects of an
intervention
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Analysis
Incidence of outcome in experimental
group
Incidence of outcome in control group
If incidence of outcome are significantly
more among the experimental group our
hypothesis is correct and vice versa
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RR from 2x2 Table
c
c + d
Incidence
among Control =
a
a + b
Incidence among
experimental group =
a/ a+ b
c / c + d
Relative Risk =
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What is blinding?
The subjects are not knowing the group
to which they are belonging This is
single blind (It is not possible for every
trial)
Neither the subject nor doctor is aware
about the groups (Double blind trials)
The subject, the doctor and the person
doing the analysis are not aware about
the groups in triple blind trials
85. 5/31/2023 DR M TAUSEEF JAVED 85
Important Issues in experimental
studies
Ethical Issues
Consent Issues
Sufficiently large willing population
required
Maintenance of Compliance
Issues in measurement of outcome
Issues of early termination of trials
Cost Issues
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Ethical Issues in human experiments
The substance already known to be
harmful are not allowed for exposure
The therapy which are known to be
beneficial are not be disallowed
Written consent is required from the
subject to be enrolled for study
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Assignment (Choosing study design)
Every participant will phrase 5 research
statements
Participants will be divided in to groups
Discuss with each other and choose most
suitable study design for each statement
Give the important steps of selected study
designs
Presentation from each group
89. 5/31/2023 DR M TAUSEEF JAVED 89
the difference between relative
risk and odds ratios
Relative Risk and Odds Ratios are often
confused despite being unique
concepts. Why?
Well, both measure association
between a binary outcome variable and
a continuous or binary predictor
variable.
90. The relative risk is confused by some with the
odds ratio and absolute risk. Relative risk is
the ratio of the probability of an event
occurring with an exposure versus the
probability of the event occurring without the
exposure. Thus to calculate the relative risk,
we must know the exposure status of all
individuals (either exposed or not
exposed). This implies that relative risk is only
appropriate for cases where the exposure
status and incidence of disease can be
accurately determined, such as prospective
cohort studies.
5/31/2023 DR M TAUSEEF JAVED 90
91. Relative Risk and Odds Ratios are often
confused despite being unique
concepts. Why?
Well, both measure association
between a binary outcome variable and
a continuous or binary predictor
variable.
5/31/2023 DR M TAUSEEF JAVED 91
98. When Is the Odds Ratio a Good
Estimate of the Relative Risk?
In a case-control study, only the odds ratio
can be
calculated as a measure of association,
whereas in a
cohort study, either the relative risk or the
odds
ratio is a valid measure of association.
5/31/2023 DR M TAUSEEF JAVED 98
99. When is the odds ratio (relative odds)
obtained
in a case-control study a good
approximation of the
relative risk in the population? When the
following
three conditions are met:
5/31/2023 DR M TAUSEEF JAVED 99
100. 1. When the cases studied are representative, with
regard to history of exposure, of all people with
the disease in the population from which the
cases were drawn.
2. When the controls studied are representative,
with regard to history of exposure, of all people
without the disease in the population from
which the cases were drawn.
3. When the disease being studied does not occur
frequently.
5/31/2023 DR M TAUSEEF JAVED 100