1. From the Center for Cerebrovascular Research, Department of Anesthesia and Perioperative Care (R.A.G., H.K., A.S.A., W.L.Y.), and Departments of Epidemiology and Biostatistics (H.K., C.E.M., S.C.J.), Neurology (V.S., S.C.J., N.K., W.L.Y.), Neurological Surgery (W.L.Y.), and Medicine (J.Z.), University of California, San Francisco, and the Division of Research (S.S., J.Z.), Kaiser Permanente Northern California, Oakland, Calif.