1. Quintiles, Inc.; 5927 S Miami Blvd; Morrisville; NC; 27560; USA
2. Department of Epidemiology, Gillings School of Global Public Health; University of North Carolina at Chapel Hill; Chapel Hill; NC; 27599; USA
3. Department of Epidemiology and Biostatistics, Arnold School of Public Health and Institute for Families in Society; University of South Carolina; Columbia; SC; 29208; USA