A laboratory measurement of some biological indicator of a drug's effectiveness, used in place of longer-term outcome measures.
a biomarker (such as the level of cholesterol in the blood) that can substitute for a clinical endpoint (such as a heart attack)
a laboratory finding or physcal sign that may not in itself be a direct measurement of how a patient feels, functions, or survives, but nevertheless, is considered likely to predict therapeutc benefit
a laboratory finding or physical sign that may not be a direct measurement of how a patient feels, functions, or survives, but is still considered reasonably likely to predict therapeutic benefit for the patient
an endpoint that is obtained sooner, at less cost, or less invasively than a true endpoint and is used to provide information on the effect of intervention on a true endpoint
an outcome measure that is used in place of a primary endpoint (outcome). Examples are decrease in blood pressure as a predictor of decrease in strokes and heart attacks in hypertensive patients, and increase in T-cell (a type of white blood cell) counts as an indicator of improved survival of AIDS patients. Use of a surrogate endpoint assumes that it is a reliable predictor of the primary endpoint(s) of interest.
In clinical trials, a surrogate endpoint is a measure of effect of a certain treatment that may correlate with a real endpoint but has no guaranteed relationship.