From the Departments of Neurology (L.L., S.A.M., M.E.F., L.M.K., E.C.R.) and Neurosurgery (R.A.S., A.B.), Neurological Institute, College of Physicians and Surgeons, and the Department of Biostatistics (M.C.P., H.Z., Y.C.W.), School of Public Health, Columbia University, New York, NY. (At 2000-02)