NCIt definition : In a clinical trial, an assessment of an intervention's effects that takes the place
of a patient-based conclusion.;
Alternative definition : CDISC-GLOSS: A measurement of a drug's biological activity that substitutes for a
clinically meaningful endpoint. [After Russell Katz, Biomarkers and Surrogate Markers:
An FDA Perspective, NeuroRx. 2004 Apr;1(2):189-95.];