Stroke Symptoms as a Surrogate in Stroke Primary Prevention Trials: The CREST Experience.

The low stroke event rates in asymptomatic patients challenges the assessment of CAS-versus-CEA treatment differences. Incorporating incident stroke symptoms as a surrogate outcome increased the number of events by over 4-fold. The analysis demonstrated a previously unreported significant difference in cerebrovascular risk with CAS compared with CEA. We propose that broadening the end points of primary stroke prevention trials to include surrogate events such as incident stroke symptoms could make trials more feasible.