Epidemiology Ch 8 Study Questions

Experimental studies can involve therapeutic or preventive trials. Provide an example for each type of trial.

A preventive trial (also known as a prophylactic trial) is used to evaluate preventive measures such as vaccines. A therapeutic trial is used to assess new treatment methods such as new forms of chemotherapy.

Match the following strenghts and weaknesses with (a) between-group design or (b) within-group design. ____ More susceptible to individual characteristics that might confound an association (e.g., age, gender, genetic susceptibility). ____ More susceptible to confounding from time-related factors (e.g., learning effects, external factors). ____ Outcome of interest is compared before and after the intervention in a single cohort.

A, B, B

Match the following definitions with the type of clinical trial: (a) preclinical, (b) phase I, (c) phase II, (d) phase III, or (e) phase IV 1) ____ Studies involving animals or cell cultures. 2) ____ Conducting to determine the safety of a treatment in humans. Patients go through intense monitoring. 3) ____ Large studies (may or may not be a randomized trial) conducted after the therapy has been approved by the FDA to assess the rate of serious side effects and explore further therapeutic uses. 4) ____ Relatively large randomized blinded trials used to evaluate the efficacy of an intervention. 5) ____ Investigator explores test tolerability, safe dosage, side effects, and how the body copes with the drug.

1) A 2) B 3) E 4) D 5) C

List five ethical problems that occurred in the Tuskegee syphilis study.

1) There was no informed consent. Patients were not told that they were participants in an experiment or that they had a contagious disease. 2) Diagnostic spinal taps for neurosyphilis were misrepresented as special free treatment when, in actuality, treatment was withheld. 3) The contagious nature of the disease was never made known to families of the infected cases, so transmission to partners and children occurred. 4) Because treatment would eliminate a case from the study, subjects were actively prevented from receiving treatment. 5) Published statistics from the study were intended to promote fear of the disease so as to prevent further support for the study.

List three reasons why interim monitoring is important in a clinical trial.

3 reasons why interim monitoring is important are to protect the patients from harmful effects, provide treatment for the patients harmed by the trial, and to ensure that the clinical trial will answer a hypothesis and/or come to a definitive end.

What are three ways to maximize compliance in a clinical trial?

3 ways to maximize compliance within a clinical trial are to provide ample incentives and/or reimbursement, maintaining contact with the patients throughout the study and follow-up, and maintain adherence to intervention protocol.

What study design minimizes bias resulting from loss to follow-up?

A Run-in Design

Match each consideration with (a) respect for persons, (b) beneficence, or (c) justice. ____ Risks associated with research participation are acceptable in relation to the potential benefits. ____ The benefits and burdens of research are distributed fairly. ____ Confidentiality ____ Informed Consent ____ Research methods are scientifically sound

B, C, A, A, B

What study design allows for answering two or more questions in a single study?

Factorial Designs

What study design allows for testing a less mature hypothesis along with a more mature hypothesis?

Factorial Designs

List some reasons that randomization might be preferred to a convenience sample.

Randomization allows for the application of inferential statistical tests of probability and determination of the levels of significance, and randomization has the advantage of eliminating bias resulting from either physician or patient selection. Additionally, randomization helps to make groups similar.

List some reasons that randomization may not be preferred to a convenience sample.

Randomization may not always be preferable because a large population may not always be available, performing a randomization study can be expensive and funds may not be available, there may be a lack of participants with the disease or condition or a desire to participate. Additionally, randomization cannot be applied if an entire population will be affected or subjected to the treatment.

What are the primary benefits of randomization?

Randomization minimizes the potential influence of confounding factors by balancing them and controlling for known and unknown confounders.

Design your own randomized controlled trial using the steps given in the chapter. Suppose it is a drug study in which it is appropriate to use a placebo.

Step 1) Write a protocol Step 2) Select the intervention Step 3) Assemble the study cohort Step 4) Measure baseline variables Step 5) Choose the comparison group Step 6) Ensure compliance of patients Step 7) Selecting the treatment Step 8) Select the end point Step 9) Ethical considerations

What type of study would be appropriate to use if it was ethical to assigns a concurrent comparison group using randomization?

The only time it would be appropriate to use a concurrent comparison group with randomization is a convenience sample.