John M. Young and James D. Mancuso are with the Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD. Shauna L. Stahlman, Shawn S. Clausen, and Mark L. Bova are with the Epidemiology and Analysis Section of the Armed Forces Health Surveillance Division at the Defense Health Agency, Silver Spring, MD. Note. The opinions and assertions expressed herein are those of the authors and do not necessarily reflect the official policy or position...