A proposed substitute
A surrogate can be measured earlier than an outcome such as overall survival. Being available sooner does not prove that it represents clinical benefit. Its usefulness can vary across diseases and interventions.
Association is not sufficient
An association between a marker and an outcome across patients does not establish that changing the marker improves that outcome. Validation requires evidence concerning the relationship between treatment effects on the proposed surrogate and on the clinical outcome.
Describe the evidence precisely
Distinguish a proposed surrogate, a validated surrogate and a measure used under particular conditions. Identify outcomes that still require follow-up. Response, progression and minimal residual disease are not universally valid substitutes in every setting.
Interpretation limits
Improvement in a surrogate endpoint does not necessarily improve survival, symptoms or quality of life.
Original references
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Research questions
Select tools by method, population and purpose. A thematic connection does not validate use in every case.
Educational content for framing research. Consult the original document, study population and methodology before interpreting a conclusion. Methodology