WEEK 8: DESIGN 3&4 EXPIREMENTAL STUDIES, QUALITIVE STUDIES

Question 1

what are observational studies

Answer 1

researchers collect, record, and analyze the data on participants as they naturally divide themselves by potentially significant exposure and outcome variables.

Question 2

what are experimental studies

Answer 2

• involve some type of intervention and control of the exposure variable by the researchers to see how this control influences the outcome variable.
• Key feature is that the conditions of the study, particularly the exposure status are directly controlled by the intervention of researchers

Question 3

6 steps to the process

Answer 3

1. Research questions for experimental studies
2. Types of experimental studies
3. Study population
4. Consent, enrollment, exposure assignment
5. Minimizing bias
6. Analysis

Question 4

what is a prevention trrial

Answer 4

Agent given to healthy or high-risk individuals to prevent disease occurrence
Ø Does removing lead-contaminated soil prevent lead poisoning in high risk urban children?

Question 5

what is a therapeutic (clinical) trial

Answer 5

Agent given to diseased individuals to treat or cure disease
Ø Does the drug Herceptin lower the risk of recurrence and improve survival among women diagnosed with breast cancer?

Question 6

what is an individual trial

Answer 6

Treatment allocated to individuals
Ø Study effectiveness of treatment with two drugs versus three drugs among adults infected with HIV

Question 7

what is a community (cluster) trial?

Answer 7

treatment allocated to an entire community

Question 8

how to choose study population

Answer 8

• depends on purpose of the trial
• Specific inclusion/exclusion criteria (eligibility criteria) based on scientific, safety, and practical considerations
  o People in population of interest, at risk for outcome, among whom intervention could be effective
  o People with a high likelihood of compliance with treatment, likely to be followed for total study period
  o May need to exclude certain people, such as those with conditions for which drug under study is contraindicated

Question 9

what is generalizability

Answer 9

extent to which the results from a study can be generalized (or extended) to people who did not participate in the study

Question 10

what is the refrence population

Answer 10

group to whom results are applicable/generalizable
- ex. all men and all women

Question 11

who must approve the study protocol before imitating the procedures

Answer 11

Institutional Review Board (IRB)

Question 12

what is informed consent?

Answer 12

includes clear explanation of research goals and methods, risks and benefits of participating, assurance of confidentiality, right to withdraw, etc.

Question 13

what is randomization

Answer 13

each study has the same probability of receiving treatment
How its achieved:
* Toss a coin; heads or tails
* Computer-generated randomization

Question 14

when are chance differences more likely to occur?

Answer 14

when the study sample is small (<100 per group). In this case, stratified randomization should be considered

Question 15

what is a cofounder

Answer 15

a factor that distorts the true association between an exposure and outcome

Question 16

what is blinding/masking

Answer 16

Method of ensuring that participants and/or study investigators have no knowledge of whether a study participant has been assigned to the treatment or comparison group

Question 17

single, double and triple blind

Answer 17

Single-blind: study participant does not know whether they are receiving treatment or no treatment
Double-blind: neither the (1) study participant nor the (2) study investigator administering the treatment knows who is receiving treatment or no treatment
Triple-blind: neither the (1) study participant nor the (2) study investigator administering the treatment nor the (3) study investigator monitoring the effects of the treatment knows who is receiving treatment or no treatment

Question 18

why use a placebo?

Answer 18

Ø Makes exposed and unexposed groups’ experiences as comparable as possible (this goal harkens back to lab experiments)
Ø One method of blinding

Question 19

what is the placebo effect?

Answer 19

Participants assigned to placebo group improve because they are told that they will. This stems from the power of suggestion.

Question 20

what is compliance

Answer 20

Following the study protocol exactly as required throughout the course of the trial

Question 21

what are the two goals of compliance

Answer 21

Ø Goal # 1: Have groups be as alike as possible on other important characteristics (randomization)
Ø Goal # 2: Have groups be as different as possible on exposure (intervention)

Question 22

strengths of randomized control trials

Answer 22

1. Demonstrate causal relationships with high level of confidence
   o Because of higher validity
2. Researchers can control exposure levels

Question 23

weaknesses of randomized control trials

Answer 23

(1) Limited applicability due to ethical reasons and at times due to artificial setting of experiment
(2) Potential for bias due to difference in compliance, withdrawal, and loss to follow-up in experimental and control groups
(3) Usually costly and time consuming
(4) May have limited external validity (low generalizability)
(5) Risk of contamination is high even in blinded studies

Question 24

community trials

Answer 24

An extension of the cluster and randomized trial where the unit of randomization is a whole community

Question 25

what is the health research process?

Answer 25

1. Research question
2. Generate hypothesis
   - Identify subjects and variables
   - exposure/outcome association
3. Collect data
   - Sample population
   - Measure variables
   Measurement error and associated misclassification happens here
4. Analyze data
   - Describe data
   - Measurement of occurrences/associations
5. Interpret findings
   - Causation
   - Bias, confounding
6. Communicate
   - Publish, present
   - Report

Question 26

randomized control trial

Answer 26

some participants are randomly assigned to an active intervention group, remaining participants are assigned to a control group, and all participants from both groups are followed forward in time to determine who has favorable outcomes and who does not

Question 27

types of success

Answer 27

superiority trial: intervention is better than the comparison
noninferiority trial: intervention is not worse than the comparison
equivalence trial: intervention is equal to comparison

Question 28

standard of care

Answer 28

an existing therapy used as a comparison for a new therapy being experimentally tested

Question 29

Hawthorne effect

Answer 29

type of bias that occurs when participants in a study change their behaviour for the better bc they know they are being observed

Question 30

detection/surveillance bias

Answer 30

occurs when a population group that is routinely screened for adverse health conditions incorrectly appears to have a higher-than-typical rate of disease bc more frequent testing enables higher case detection rate in the population than i the general population

Question 31

simple randomization

Answer 31

use of a coin toss, a random # generator, simple mechanisms that randomly assign individuals to an exposure group

Question 32

stratified randomization

Answer 32

the didion of a population into subgroups prior to randomly buy systematically assigning each individual within each subgroup to 1 of the exposure groups

Question 33

adverse reaction vs adverse event

Answer 33

Adverse reaction - negative side effect of an exposure (i.e medication, vaccination) or a bad outcome related to a study
Adverse event - negative outcome that is the direct result of a study-related exposure or a coincidental occurrence that is not directly related to the study but happens after an individual receives a study-related exposure

Question 34

efficacy

Answer 34

measure of the success of an intervention that is calculated as the proportion of individuals within the control group who experienced an unfavorable outcome but cold have expected to have a favorable outcome if they were assigned to the active group instead of the control group

Question 35

what is screening

Answer 35

type of secondary prevention in which all members of a well-define group of people are encouraged to be tested for a disease based on evidence that members of the population are at risk for the disease, and early intervention improves health outcomes

Question 36

positive and negative predictive value

Answer 36

Positive Predictive Value (PPV) - proportion of people who test positive with the ne test who actually have the disease (according to reference standard)
Negative Predictive Value (NPV) - proportion of people who test negative with the new test who actually do NOT have the disease (according to reference standard)

Question 37

Which of the following are experimental studies that aim to demonstrate that a new intervention is better than some type of control?

Answer 37

superiority trial