[1] Southeast Colorado Hosp, Dept Phys Therapy & Rehabil, Springfield, CO 81073 USA
[2] Univ Nebraska, Coll Allied Hlth Profess, Dept Hlth & Rehabil Sci, Med Ctr, Omaha, NE 68198 USA
[3] Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA
[4] Univ Southern Calif, Hlth Res Assoc Keck Med, Los Angeles, CA USA
[5] Chinese Acad Med Sci, Beijing Hosp, Inst Geriatr Med, Natl Ctr Gerontol,Dept Rehabil Med, Beijing, Peoples R China
[6] Shanghai Sixth Peoples Hosp, Dept Rehabil Med, Shanghai, Peoples R China