Deck 10: Assessing Preventive and Therapeutic Measures: Randomized Trials

Question 1

Participants in a clinical trial might report different symptoms when they know they are part of the intervention group instead of the control group.To avoid that,researchers use the following:

A) Confounding
B) Randomization
C) Concealment of random allocation
D) Masking
E) Effect modifiers

Answer 1

D
Masking is used to prevent participants from knowing whether they are receiving an intervention (most times a drug) or a control (placebo).

Question 2

In a clinical trial,researchers might influence the selection of participants into a group (intervention or control),hence introducing bias into the study.What can be done to prevent from this threat to the validity of the study?

A) Confounding
B) Randomization
C) Concealment of random allocation
D) Masking
E) Effect modifiers

Answer 2

B
The main purpose of randomization is to prevent the potential bias on the part of the investigators from assigning participants into the groups of the trial.

Question 3

Two similar drugs (drug A and drug B) to alleviate back pain were released simultaneously.An investigator decides to test which of the drugs works better.He decides to conduct a trial in which randomly,half of the participants receive drug A for a month while the other half received drug B.After 2 weeks without any medication,participants switch the drug they were receiving (those who received A start taking B,and those who received B start taking A).What type of study design was illustrated in this example?

A) Cross-sectional study
B) Factorial randomized clinical trial
C) Crossover randomized clinical trial
D) Crossover cohort study
E) Phase II clinical trial

Answer 3

C
In a crossover clinical trial,participants receive one drug and later switch to another one.The effect of these drugs is compared within the same population.

Question 4

In a clinical trial,sometimes patients agree to receive an intervention but later decide to stop taking the medication.Moreover,some patients who were assigned to placebo decide to stop taking the placebo pill and buy the drug on their own (even when they do not know that they are taking a placebo pill).When this happens,researchers typically do the analysis according to the original assignment of the treatment regardless of the actual treatment received.What is the name of this procedure to analyze the data?

A) Randomization
B) Intention-to-treat analysis
C) Concealment of random allocation
D) Analysis as treated
E) Mediation analysis