[1] Univ Pittsburgh, Dept Phys Med & Rehabil, Med Ctr, Pittsburgh, PA USA
[2] Univ Pittsburgh, Med Ctr, Brady Lib Hlth Sci, Pittsburgh, PA USA
[3] Univ Toronto, Dalla Lana Sch Publ Hlth, Dept Epidemiol, Toronto, ON, Canada
[4] Yale Univ, Sch Publ Hlth, Dept Social & Behav Sci, 60 State St, New Haven, CT 06510 USA