Which term describes a secondary outcome used as a proxy for a clinical outcome?

• A. Surrogate endpoint
• B. Primary endpoint
• C. Composite endpoint
• D. Exploratory endpoint

Answer: (A)

A surrogate endpoint is used when a secondary measure serves as a stand-in for the actual clinical outcome of interest. It’s typically a biomarker or intermediate result that is believed to predict the real patient-relevant outcome, allowing researchers to gauge potential benefit (or harm) earlier or with fewer participants. For example, lowering LDL cholesterol is a surrogate endpoint often used to anticipate a reduced risk of cardiovascular events, while blood pressure reduction is used to predict fewer strokes or heart attacks. The other terms don’t fit this idea: the primary endpoint is the main outcome the trial is designed to assess; a composite endpoint combines multiple outcomes into one measure; an exploratory endpoint is investigated to generate new hypotheses and isn’t the primary basis for conclusions.