BS - Epi/Biostat (Studies & Clinical Trials)
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Which of the following studies are observational, prospective, and/or retrospective: (1) Cross-sectional study (2) Case-control study (3) Cohort study?
(1) Observational (2) Observational and Retrospective (3) Observation and Prospective or Retrospective
Describe the design of cross-sectional study. What question does it ask?
Collects data from a group of people to assess frequency of disease (and related risk factors) at a particular point in time. Asks, “What is happening?”
What is a measure/example of cross-sectional study?
Disease prevalence
How does cross-sectional study relate to risks and causality?
Can show risk factor association with disease but does not establish causality
Describe the design of the case-control study. What does it look for? What question does it ask?
Compares a group of people with disease to a group without disease. Looks for prior exposure or risk factor. Asks, “What happened?”
What is a measure/example of case-control study?
Odds ratio (OR); “Patients with COPD had higher odds of a history of smoking than those without COPD had”
Describe the design of a cohort study. What does it look for? What questions can it ask?
Compares a group with a given exposure or risk factor to a group without such exposure. Looks to see if exposure increases the likelihood of disease. Can be prospective (asks, “Who will develop disease?”) or retrospective (asks, “Who developed the disease [exposed v. unexposed]?”)
What is a measure/example of cohort study?
Relative risk (RR); “Smokers had a higher risk of developing COPD than nonsmokers had.”
Describe the design of twin concordance study.
Compares the frequency with which both monozygotic twins or both dizygotic twins develop same disease
What does twin concordance study measure? What other study measures this as well?
Measures heritability and influence of environmental factors (“nature vs. nurture”); Adoption study
Describe the design of adoption study.
Compares siblings raised by biological vs. adoptive parents
What is a clinical trial? Describe its design.
Experimental study involving humans. Compares therapeutic benefits of 2 or more treatments, or of treatment and placebo.
What improves the study quality of clinical trials?
Study quality improves when study is randomized, controlled, and double-blinded (i.e., neither patient nor doctor knows whether patient is in the treatment or control group)
What defines triple-blind in the context of a clinical trial?
Triple-blind refers to the additional blinding of the researchers analyzing the data.
How many major phases of a drug trial are there?
(1) Phase I (2) Phase II (3) Phase III (4) Phase IV
What is the the typical study sample in Phase I of a clinical trial? What question does it ask? What is its purpose?
Small number of healthy volunteers; “Is it safe?” Assesses safety, toxicity, and pharmacokinetics
What is the the typical study sample in Phase II of a clinical trial? What question does it ask? What is its purpose?
Small number of patients with disease of interest; “Does it work?” Assesses treatment efficacy, optimal dosing, and adverse effects
What is the the typical study sample in Phase III of a clinical trial? What question does it ask? What is its purpose?
Large number of patients randomly assigned either to the treatment under investigation or to the best available treatment (or placebo); “Is it as good or better?” Compares the new treatment to the current standard of care
What is the the typical study sample in Phase VI of a clinical trial, and in what context does it occur? What question does it ask? What is its purpose? What can result from it?
Postmarketing surveillance trial of patients after approval; “Can it stay?” Detects rare or long-term adverse effects. Can result in a drug being withdrawn from market.