1. From the Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD (E.D.K., S.H.B., J.C., K.M.)
2. Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, MD (E.D.K., S.H.B., J.C., K.M.)
3. Department of Kinesiology and Health Education, University of Texas at Austin, TX (H.T.)
4. Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC (G.H.).