[1] Meyers Primary Care Inst, Fallon Healthcare Syst, Worcester, MA 01605 USA
[2] Natl Canc Inst, Div Canc Control & Populat Sci, Rockville, MD USA
[3] Henry Ford Hlth Syst, Detroit, MI USA
[4] Grp Hlth Cooperat Puget Sound, Ctr Hlth Studies, Seattle, WA USA
[5] Univ Massachusetts, Sch Med, Worcester, MA USA
[6] Kaiser Permanente NW, Ctr Hlth Res, Portland, OR USA