1. From the Northwestern University Feinberg School of Medicine (D.V., S.M., H.C., R.G.), Chicago, IL; Columbia University (J.M.), New York, NY; Westat, Inc. (K.W.-A., R.H.), Rockville, MD; University of Maryland (N.F.), College Park, MD; Indiana University School of Medicine (C.P., H.H.), Indianapolis, IN; and University of Washington (M.H.), Seattle, WA.