Term
Surrogate endpoint
A substitute measurement, usually a lab or imaging marker, standing in for how a patient actually feels, functions or survives.
A surrogate endpoint measures something expected to predict clinical benefit rather than the benefit itself: cholesterol instead of heart attacks, a biomarker instead of survival. Surrogates make trials faster and smaller, at the cost of an inference: the assumption that moving the marker moves the outcome.
Regulators accept some surrogates as approvable primary endpoints because the link is well established: blood pressure in hypertension, HbA1c in type 2 diabetes, LDL cholesterol for lipid-lowering therapy. This site's grading rubric treats those regulator-accepted, disease-defining measures as hard endpoints; an unvalidated marker is graded as the weaker evidence it is.
On this site: The rubric's endpoint rules ↗
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