This document provides an overview of case-control studies in epidemiology. It defines case-control studies, outlines their basic steps including selection of cases and controls and measurement of exposure. It also discusses analysis and interpretation through estimation of risk and odds ratios. Potential biases in case-control studies are described such as selection bias, information bias, and confounding. Both advantages like being rapid and inexpensive, and disadvantages like relying on memory are summarized.
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.
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 .
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.
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.
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.
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 .
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.
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.
Social and Preventive Medicine Classroom discussion topic on types of Epidemiological study designs available.
sole reference is Park text book 20th edition
Observational research designs are those in which the researcher/investigator merely observes and does not carry out any interventions/actions.
to change the result. The three most common types of observational studies are cross-sectional studies, case-control studies, and cohort (or longitudinal) studies.
In cross-sectional studies, exposure/risk factors and outcomes are determined at a single point in time. You can bid
information on disease prevalence and an overview of likely relationships that can be used to form a hypothesis. Control cases In
studies, participants are selected based on the presence/absence of an outcome and risk factors are identified during the study.
after enrollment of study participants.The relationship between exposure and outcome is reported as an odds ratio. This research; However,
carries a high risk of bias, which should be taken into account when designing the study. Cohort studies are prospective and include participants
were selected based on presence/absence of exposure and results were obtained at the end of the study. This research can deliver The incidence/impact of the disease and the relationship between exposure and outcome are presented as relative risks. They are useful
establish causality.A problem that arises in these studies could be the high fluctuation and dropout of study participants.
Descriptive studies generally describe the magnitude of a problem and characteristics of the population/individuals.
The various types of such studies include
case reports
case series or surveys.
A case report generally describes a patient presenting with an unusual disease, or simultaneous occurrence of more than one condition, or uncommon clinical features in a known disease.
A case series is a collection of similar cases. Such studies, other than providing some advancement to knowledge of a disease, are of limited value. Another method often used in epidemiological health care research is conducting surveys.
Surveys are done during a defined time-period and information on several variables of interest is collected from the target population. They provide estimates of prevalence of the various variables of interest, and their distribution. Such studies could also provide insight into individual opinions and practices. Advantages include ease of conduct and cost efficiency. The disadvantages include low response rates and a variety of biases.
An analytical study tests a hypothesis to determine an association between two or more variables, like causation, risk, or effect. Such studies have two or more study groups for comparison.
The primary focus of this article will be the three most common types of analytical observational studies –
cross-sectional,
case control (also known as retrospective) and
cohort (or longitudinal, also known as prospective) studies.
It may be pertinent to note that the primary objective of most clinical studies is to determine one of the following - burden of disease (prevalence
ICH Guidelines for Pharmacovigilance.pdfNEHA GUPTA
The "ICH Guidelines for Pharmacovigilance" PDF provides a comprehensive overview of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines related to pharmacovigilance. These guidelines aim to ensure that drugs are safe and effective for patients by monitoring and assessing adverse effects, ensuring proper reporting systems, and improving risk management practices. The document is essential for professionals in the pharmaceutical industry, regulatory authorities, and healthcare providers, offering detailed procedures and standards for pharmacovigilance activities to enhance drug safety and protect public health.
Health Education on prevention of hypertensionRadhika kulvi
Hypertension is a chronic condition of concern due to its role in the causation of coronary heart diseases. Hypertension is a worldwide epidemic and important risk factor for coronary artery disease, stroke and renal diseases. Blood pressure is the force exerted by the blood against the walls of the blood vessels and is sufficient to maintain tissue perfusion during activity and rest. Hypertension is sustained elevation of BP. In adults, HTN exists when systolic blood pressure is equal to or greater than 140mmHg or diastolic BP is equal to or greater than 90mmHg. The
Leading the Way in Nephrology: Dr. David Greene's Work with Stem Cells for Ki...Dr. David Greene Arizona
As we watch Dr. Greene's continued efforts and research in Arizona, it's clear that stem cell therapy holds a promising key to unlocking new doors in the treatment of kidney disease. With each study and trial, we step closer to a world where kidney disease is no longer a life sentence but a treatable condition, thanks to pioneers like Dr. David Greene.
The dimensions of healthcare quality refer to various attributes or aspects that define the standard of healthcare services. These dimensions are used to evaluate, measure, and improve the quality of care provided to patients. A comprehensive understanding of these dimensions ensures that healthcare systems can address various aspects of patient care effectively and holistically. Dimensions of Healthcare Quality and Performance of care include the following; Appropriateness, Availability, Competence, Continuity, Effectiveness, Efficiency, Efficacy, Prevention, Respect and Care, Safety as well as Timeliness.
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.
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.
2. Index
1-INTRODUCTION AND DEFINAION
2-ANALYTICAL STUDY – CASE CONTROL STUDY
3-BASIC STEPS
4-MATCHING TYPE MEASUREMENTS OF EXPOSURE AND RATES
5-ANALYSIS AND INTREPRETATION
6-ESTIMATON OF RISK AND ODD RATIO
7-BAIS IN CASE CONTROL STUDY
8-ADVANTAGE OF CASE CONTROL STUDY
9-DISADVANTAGE OF CASE CONTROL STUDY
3. INTRODUCTION
The word epidemiology is derived from the
Greek word, Epidemic. Epi=upon, demos·
people and logos=study or science.
Epidemiology covers not only the study of
disease distribution and causation but also of
health and health related events occurring in
human populations.
4. John M. Last (1988) defines epidemiology
as me study of the distribution and
determinants of health related states or
events in specified population and the
application of this study to the control of
health problems.
DEFINATION
5. AIMS OF EPIDEMIOLOGY
1-To describe the size and the distribution of the
disease problem in human populations
2-To provide the data essential for the planning,
implementation and evaluation of health services for
the prevention, control and treatment of diseases and
for the setting up of priorities among those services
3-To identify etiological factors in the pathogenesis of
disease.
6. PRINCIPLES OF EPIDEMIOLOGY
The principles of epidemiology as a scientific field of
science are related to the basic principles of science.
The four important principles are:
Exact Observation
1. exact observation
2. Correct Interpretation
3. Rational Explanation (intelligent, sensible,
reasonable)
4. Scientific Construction
8. ANALYTICAL EPIDEMIOLOGY
They are the second major type of epidemiological
studies. The focus here is the individual within a
Population unlike descriptive epidemiology which
focuses on the entire Population. It is designed primarily
to establish the causes of disease by investigating
association between exposure to a risk factor and the
occurrence of disease. The objective is to test the
hypothesis.
They are of 2 types,
a. Case control study
b. Cohort study
9. CASE CONTROL STUDY
Its are a common first approach to test causal hypothesis,
The case control method has three distinct features:
1- both exposure and outcome (disease) have occurred before
the start of the study .
2-the study proceeds backwards from effect to cause; and
3, it uses control or comparison group to support or refute an
inference
10. The design is backward-looking (retrospective), based on the
exposure histories of cases and controls. E.g. If it is our
intention to test the hypothesis that "tobacco chewing causes
oral cancer': using the case control method, the investigation
begins by assembling a group of oral cancer cases and a group
of suitably matched controls. One then explores the past
history of these two groups for the presence or absence of
tobacco chewing, which is suspected to be related to the
occurrence of oral cancer If the frequency of tobacco chewing
is higher in cases than in controls, an association is said to
exist between tobacco chewing and oral cancer .
11. Basic steps :
There are four basic steps in conducting a case control study:
1.Selection of cases and controls
2. Matching
3. Measurement of exposure, and
4.Analysis and interpretation
12. 1. Selection of cases and controls :
The first step is to identify a suitable group of cases and a
group of controls
(I) Diagnostic criteria: the diagnostic criteria of the
disease and the stage of disease if any t to include in the
study must be specified before the sutdies under taken.
While investigating cases of cancel; cases s could be
histologically the same. once the diagnostic criteria: are
established, there should not b e alter or change till the
study is over
(ii) Eligibility criteria The second criterion is that of
eligibility A criterion customarily employed is the
requirement that only newly diagnosed (incident). cases
within a specified period of time are legible than old
cases or cases in advanced stages of the disease (prevalent
cases). It eliminates the possibility that long term
survivors of a disease were exposed to the. Investigated
risk factor after the onset o disease
13. Sources of cases:
(1)HOSPITALS: it is often convenient to select cases from
hospitals, The cases may be drawn from a hospital
admitted during a specified period of time. The entire
case series or a random sample of it is selected for the
study.
(2)GENERAL POPULATION: in a population-based case
control study all cases of the study disease occurring
within a defined geographic area during a specified period
of time are ascertained, often through a survey, a disease
registry or hospital network. The entire case series or a
random sample of it is selected for the study., The cases
should be fairly representative of all cases in the
community
14. HOSPITAL CONTROLS:
The controls may be selected from the same hospital as
the cases, but with different illnesses other than the study
disease. For example, if we are going to study oral cancer
patients, the control group may comprise patients with
cancer breast, cancer of the digestive tract, or patients
with non-cancerous lesions and other patients.
15. B) Selection of controls The controls must be free from the
disease under study. They must be as similar to the of the
disease under study. As a rule, a cases as possible, except for the
absence comparison group is identified before a study is done,
comprising of persons who have not been exposed to the
disease. Difficulties may arise in the selection of controls if the
disease under investigation occurs in subclinical forms whose
diagnosis is difficult. Selection of an appropriate control group
is therefore an important prerequisite, for it is against this, we
make comparisons, draw inferences make judgments about the
outcome the investigation.
16. 2. Matching The controls may differ from the cases in a
number of factors such as age, sex, occupation, social
status, etc. An important consideration is to ensure
comparability between cases and controls This involves
what is known as "matching“
. Matching is defined as the process by which we
select controls in such a way that they are similar to cases
with regard to certain pertinent selected variables (e.g, age)
which are known to influence the outcome of disease and
which, if not adequately matched for comparability, could
distort or confound the results".
17. Types of matching
Group matching (frequency matching): This may be done
by assigning cases to sub categories (strata) based on their
characteristics (e.g., age. occupation, social class) and then
establishing appropriate controls. The frequency
distribution of the matched variable must be similar in study
and comparison groups.
Pair matching (One to one basis or individual matching):
For example, for each case, a control is chosen which can be
matched quite closely. Thus, if we have a 50-year old mason
with particular disease, we will search for 50-year old mason
without the disease as a control. Thus one can obtain pairs of
patients and controls of the same sex, age etc.
18. 3. Measurement of exposure and other
factors
Definitions and criteria about exposure (or
variables which may be of etiological importance) are just as
important as those used to define cases and controls.
This may be obtained by .
*interviews
*questionnaires
*studying past records of cases such as hospital records,
*employment records, etc.
clinical or laboratory examination
19. 4. Analysis and interpretation
The final step is analysis, to find out :
1-Exposure rates among cases and controls to suspected factor
with exposure (Odds ratio)
2-estimation of disease risk associated with exposure
(a) EXPOSURE RATES A case control study provides a direct
estimation of the exposure rates(frequency exposure) to a
suspected factor in estimation of the exposure rates E.g. In
a case control study of tobacco chewers and oral cancer
Example of a case control study tobacco chewing and oral
cancer
20. B-ESTIMATION OF RISK
IT is defined as the Ratio between the incidence of
disease among Exposed incidence among non-
exposed. It is given by the formula.
Relative risk
Incidence among exposed /Incidence among non-
exposed
(a +b)/(c+d)
Odds Ratio (OR) It is a measure of the strength of
the association between risk factor and outcome. ,
Odds ratio is closely related to relative risk.
21. Bias in case-control studies
Bias is any systematic error in the determination of the association
between the exposure and disease. The possibility of bias must be
considered when evaluating a possible cause and effect relationship.
1. Selection bias Selection bias is a distortion of the estimate of effect
resulting from the manner which the study population is selected. The
cases and controls may not be representative of cases and controls in the
general population.
2. Information bias (In measurement of exposure or outcome
a Memory or recall bias: When cases and controls are asked questions
about their past history, it may be more likely for the cases to recall the
existence of certain events or factors than the controls who are healthy
persons..
Telescopic bias: If a question refers to recent past episodes that occurred
longer ago may also be reported
22. 3. Bias due to confounding
Mention has already been made about confounding as an
important source of bias. This bias can be removed by
matching in case control studies. Advantages of case
control studies a. Relatively easy to carry out b. Rapid and
inexpensive .
23. Advantages of case-control studies
a. Relatively easy to carry out .
b. Rapid and inexpensive (compared with cohort
studies) Requires comparatively few subjects
d. Particularly suitable to investigate rare diseases or
diseases about which little is known
d. No risk to subjects
f. Allows the study of several different etiological
factors (e.g, tobacco chewing, alcohol and genetic
factors oral cancer)
g. Risk factors can be identified. Rational prevention
and control programs can be established
h. No attrition problems, because case control studies
do not require follow- up of individuals into the
future i. Ethical problems minimal
24. Disadvantages of case-control studies
a. Problems of bias since it relies on memory or past
records, the accuracy of which may be uncertain;
validation of information obtained is difficult or
sometimes impossible
b. Selection of an appropriate control
c. We cannot measure incidence, and
d. d. Does not distinguish between causes group may be
difficult can only estimate the relative risk and
associated factors. Temporality is a serious problem in
many case- control studies where it is not possible to
determine whether the attribute led to the
disease/condition, or vice versa
e. Not suited for the evaluation of therapy or prophylaxis
of disease