1. From the Division of Nephrology, San Francisco VA Medical Center, San Francisco, CA (KLJ); the Division of Nephrology, University of California, San Francisco Medical Center, San Francisco, CA (KLJ, GMC, and BY); the Departments of Medicine and of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA (KLJ and GMC); and the Department of Rehabilitation Medicine