LECTURE 5 (Epidemiological studies) Flashcards by Nerisse Rogador

What do Epidemiologists study?

The distribution and determinants of frequency of disease in humans

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What is the difference between Incidence rate and Prevalence rate?

Incidence rate = The number of NEW DISEASES in a defined population at risk over a defined period of time

Prevalence rate = The number of EXISTING CASES in a defined population at a single point in time
[both new AND existing cases]

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What is more useful in identifying causes of diseases? (Incidence/Prevalence rate)

Incidence rate

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What is the formula to calculate Incidence rate?

New cases of a specified disease reported during a given time interval / Average population during time interval

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What is Incidence rate important for?

Tracking the spread of infectious diseases
Identifying disease outbreaks
Evaluating the impact of preventative measures and interventions
Occurrence of new cases
Risk factors associated with the onset of various diseases or health conditions

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What is the formula for calculating the prevalence rate?

Number of existing cases / Total population X 100

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Which questions does Descriptive epidemiology ask?

Who?
Where?
When?

Explanation: This information on the distribution of disease may lead to hypothesis about the determinants, or causes of disease

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What is the primary purpose of an epidemiological study?

To investigate the distribution and determinants of health-related events in populations

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What are the different Epidemiological studies?

Observational studies
Experimental studies
Ecological studies
Case-reports

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What are the three types of Observational studies?

Cohort studies
Case-control studies
Cross-Sectional studies

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Describe Cohort studies

A group of people is followed over time to determine the incidence of a specific disease
Study population is defined by exposure status or by disease status

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Describe Case-control studies

Individuals with a specific disease are compared to a group without the disease
Aim is to identify risk factors that may be associated with the disease

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Describe Cross-sectional studies

Data is collected at a single point in time from a population to determine the prevalence of a disease or health condition

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Describe Experimental studies

Interventional studies that are designed to test the efficacy of a specific treatment or intervention
In RANDOMISED CONTROLLED TRIALS (RCTs), individuals are randomly assigned to a treatment group or a control group -> aim is to compare the outcomes of the two groups to determine the efficacy of the treatment

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Describe Ecological studies

Investigate the correlation between population-level exposure to risk factors and the incidence of disease or health outcomes

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What is a Case report?

A detailed description of a single case of a disease or health condition

What are Intervention studies?

True experiments in which subjects are assigned to either a treatment group or a control group and are usually undertaken to test a new treatment for a disease

What is the most common and rigorous type of intervention study?

Randomised double-blinded clinical trial

What are the limitations of Intervention study?

Ethical reasons
Trial is too difficult to conduct

What is a placebo and what is its function?

A placebo is an inactive substance similar in appearance to the drug or vaccine being tested

FUNCTION:
to prevent participants knowing whether they are receiving the intervention
[the drug being tested must show a higher response rate than the placebo if it is to be considered effective]

What does “Randomised” mean?

Each subject is assigned to the treatment group or the control group at random through random allocation using methods like a coin toss or computer-generated randomisation

What does “Double-blind” mean?

Both the patient and the physician are blind as to whether the patient is receiving the drug or a placebo

Why must the physician also be blinded?

Patients will respond more favourably to a treatment that the doctor believes in
Prevent the possibility that doctors might interpret the patient’s condition differently if they know how the patient is being treated

What does the FDA require before a drug is approved for marketing?

Safety
Effectiveness
of any new drug demonstrated in a properly conducted clinical trial

How is health research ensured to be safe?

- Studies designed with low risk - Protections and safeguards required by law - INSTITUTIONAL REVIEW BOARD (IRB) reviews and approves each protocol

What is the Institutional Review Board (IRB)?

Made up of a team of doctors, nurses, researchers and members of the community, The IRB reviews and approves each protocol and makes sure that there is little risk for participants

What is given to the research volunteers by the study staff before the study begins?

Informed consent

What is the Data and Safety Monitoring Boards (DSMB)?

A committee of doctors who are not part of the study and closely monitor safety data of studies that have more risk

What is the function of the Data and Safety Monitoring Boards (DSMB)?

- Regularly look at the results during the study - Ensures risk is small - Can stop study at any time either because of NEW CONCERNS OF SAFETY or because the study proved that the NEW DRUG ISN'T BETTER THAN THE OLD ONE

What happens before clinical trials on humans?

1) Research labs 2) Tested in animals

What are the different phases of Clinical trials?

- PHASE 1: test a new drug for the first time in a small group of people (20-80) to see if SAFE, CORRECT DOSE and SIDE EFFECTS - PHASE 2: more people (100-300) to see EFFICACY of drug - PHASE 3: large groups of people (1000-3000) to see how it COMPARES to other drugs - PHASE 4: studies done after APPROVED by FDA

What is a Cohort study?

A type of observational study where a group of individuals who share a common characteristic or experience are followed over a period of time to observe and analyse the incidence and outcomes of specific health-related events or diseases

When are Cohort studies often used in Epidemiology?

To investigate the causes of diseases and to identify risk factors associated with the development of a particular disease [powerful tool for investigating the associations between exposures and outcomes]

How are Cohort studies conducted?

1) Starts with a group of people free of the disease at the beginning of the study 2) Participants divided into two or more groups based on EXPOSURE STATUS and study follows them over time to see if any of them develop the disease of interest

What is the difference between Prospective cohort study and Retrospective cohort study?

Prospective cohort study = study participants are identified and followed forward in time Retrospective cohort study = study participants are identified based on historical data and followed backward in time

What are case-control studies?

Start with people who are already ill and look back in time to determine their exposure and asks questions about their previous exposures, comparing their answers with those of a healthy group

How are case-control studies more efficient than cohort studies?

- They focus on a smaller number of people (cost-effective) - Completed relatively quickly