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1. What is the most important criteria in selecting subjects for clinical studies?
Answer: Scientific objectives
Explanation: The selection of study subjects must align with the scientific goals of the research,
ensuring that the study can answer the research question effectively. Factors like the disease
under study, treatment modalities, and outcome measures all depend on scientific objectives.
2. Which statement about the IRB is INCORRECT?
Answer: The members of the IRB/IEC must be experts in the topic of the study.
Explanation: The members of an Institutional Review Board (IRB) or Independent Ethics
Committee (IEC) do not have to be experts in the topic of the study, but they must have the
expertise to review the ethical aspects of the study. The IRB’s main role is to ensure that the
study protects participants' rights and welfare, not necessarily to evaluate scientific expertise.
3. Which phases of clinical studies are "open label" and which are blinded?
Answer: Phase I and IV trials are often open label, but Phase II and III are double-blinded or at
least blinded.
Explanation: Phase I trials often involve healthy volunteers to assess safety and are typically
open label. Phase II and III trials, which assess efficacy and safety in larger patient populations,
are usually blinded to prevent bias. Phase IV trials, conducted after approval, are sometimes
open label as they involve post-marketing surveillance.
4. If it is not possible to measure the direct effects of a drug, what is used instead?
Answer: Surrogate markers such as blood pressure and cholesterol levels
Explanation: Surrogate markers are indirect measures used when direct measures of a drug’s
effect are difficult to obtain. They are typically biological indicators that are associated with a
clinical outcome, such as blood pressure or cholesterol levels in cardiovascular studies.
5. Which of the following is an observational study that first identifies a group of subjects
with a certain disease and a control group without the disease, and then looks back in time
to find exposure risk factors?