Complex Made Simple: A Quick Guide to Patient-Reported, Surrogate, and Composite Outcomes .

Patient-reported, surrogate, and composite outcomes play an increasing role in trials and guidelines, making clear interpretation essential. Patient-reported outcomes capture symptoms and quality of life directly from patients but often vary in validity, reliability, and interpretability. Surrogate outcomes offer efficiency by substituting laboratory or physiologic markers for outcomes like death or disability, yet they can mislead when weakly linked to what truly matters. Composite outcomes combine several endpoints to boost event rates and power, but overall effects may be driven by less important components. Understanding these limitations helps support sound evidence interpretation.