[1] Johns Hopkins Univ, Johns Hopkins Disabil Hlth Res Ctr, 3400 N Charles St, Baltimore, MD 21218 USA
[2] Johns Hopkins Sch Med, Wilmer Eye Inst, 600 N Wolfe St, Baltimore, MD 21287 USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Epidemiol, 615 N Wolfe St, Baltimore, MD 21205 USA
[4] Utah State Univ, Inst Disabil Res Policy & Practice, 6807 Old Main Hill, Logan, UT 84322 USA
[5] Johns Hopkins Bloomberg Sch Publ Hlth, Johns Hopkins Biostat Ctr, 615 N Wolfe St, Baltimore, MD 21205 USA
[6] Univ Cincinnati, Coll Med, Dept Pediat, Cincinnati Childrens Hosp Med Ctr, 3333 Burnet Ave, Cincinnati, OH 45229 USA