[1] Emory Univ, Dept Rehabil Med, Atlanta, GA 30322 USA
[2] Birmingham Atlanta GREEC, Atlanta VA Med Ctr, Atlanta, GA USA
[3] Univ Calif Los Angeles, Sch Med, Los Angeles, CA 90024 USA
[4] RAND Corp, Santa Monica, CA 90406 USA
[5] Johns Hopkins Univ, Sch Med, Div Geriatr Med & Gerontol, Baltimore, MD 21218 USA