[1] Virginia Commonwealth Univ, Dept Pediat, Richmond, VA 23219 USA
[2] Virginia Commonwealth Univ, Dept Family Med & Populat Hlth, Richmond, VA 23219 USA
[3] Virginia Commonwealth Univ, Dept Biostat, Richmond, VA 23219 USA
[4] Virginia Commonwealth Univ, Childrens Hosp Richmond, Richmond, VA 23219 USA
[5] Oregon Hlth & Sci Univ, Dept Family Med, Portland, OR 97201 USA
[6] OCHIN, Portland, OR USA
[7] Univ Vermont, Dept Pediat, Robert Larner Coll Med, Burlington, VT USA
[8] Univ Washington, Dept Pediat, Seattle, WA 98195 USA