LECTURE 5 (Epidemiological studies)

Question 1

What do Epidemiologists study?

Answer 1

The distribution and determinants of frequency of disease in humans

Question 2

What is the difference between Incidence rate and Prevalence rate?

Answer 2

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]

Question 3

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

Answer 3

Incidence rate

Question 4

What is the formula to calculate Incidence rate?

Answer 4

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

Question 5

What is Incidence rate important for?

Answer 5

• 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

Question 6

What is the formula for calculating the prevalence rate?

Answer 6

Number of existing cases / Total population X 100

Question 7

Which questions does Descriptive epidemiology ask?

Answer 7

• Who?
• Where?
• When?

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

Question 8

What is the primary purpose of an epidemiological study?

Answer 8

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

Question 9

What are the different Epidemiological studies?

Answer 9

• Observational studies
• Experimental studies
• Ecological studies
• Case-reports

Question 10

What are the three types of Observational studies?

Answer 10

• Cohort studies
• Case-control studies
• Cross-Sectional studies

Question 11

Describe Cohort studies

Answer 11

• 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

Question 12

Describe Case-control studies

Answer 12

• 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

Question 13

Describe Cross-sectional studies

Answer 13

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

Question 14

Describe Experimental studies

Answer 14

• 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

Question 15

Describe Ecological studies

Answer 15

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

Question 16

What is a Case report?

Answer 16

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

Question 17

What are Intervention studies?

Answer 17

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

Question 18

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

Answer 18

Randomised double-blinded clinical trial

Question 19

What are the limitations of Intervention study?

Answer 19

• Ethical reasons
• Trial is too difficult to conduct

Question 20

What is a placebo and what is its function?

Answer 20

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]

Question 21

What does “Randomised” mean?

Answer 21

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

Question 22

What does “Double-blind” mean?

Answer 22

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

Question 23

Why must the physician also be blinded?

Answer 23

• 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

Question 24

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

Answer 24

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

Question 25

How is health research ensured to be safe?

Answer 25

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

Question 26

What is the Institutional Review Board (IRB)?

Answer 26

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

Question 27

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

Answer 27

Informed consent

Question 28

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

Answer 28

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

Question 29

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

Answer 29

• 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

Question 30

What happens before clinical trials on humans?

Answer 30

1) Research labs
2) Tested in animals

Question 31

What are the different phases of Clinical trials?

Answer 31

• 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

Question 32

What is a Cohort study?

Answer 32

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

Question 33

When are Cohort studies often used in Epidemiology?

Answer 33

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]

Question 34

How are Cohort studies conducted?

Answer 34

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

Question 35

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

Answer 35

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

Question 36

What are case-control studies?

Answer 36

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

Question 37

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

Answer 37

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