Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA.|Department of Biostatistics, School of Public Health, Medical College of Soochow University, Suzhou, China.|Department of Biostatistics, Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, GA, USA.|Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA.