surrogate endpoint

An indicator that, while not being of direct interest for the patient, may reflect important outcomes.

Note: For example, blood pressure is not of direct clinical interest to the patient, but is often used as an evaluation criterion in clinical trials because it is a risk factor for stroke and heart attacks. An intermediate outcome is often a physiological or biochemical marker that can be quickly and easily measured, and that is considered to have great predictive value. It is often used when observation of clinical outcomes requires long follow-up.

Note: Intermediate outcome is not a synonym for surrogate endpoint. However, an intermediate outcome can become a surrogate endpoint if it is easier to measure than a clinical criterion or if there is a statistical relationship between the occurrence of the clinical outcome indicator and the occurrence of the surrogate endpoint, or if there is a relationship allowing for prediction of the effect of the factor studied on the clinical indicator, on the basis of the observed effect on the surrogate endpoint.