Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA. kkim@ms.soph.aub.edu|Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA. kkim@ms.soph.aub.edu|Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA. kkim@ms.soph.aub.edu|Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA. kkim@ms.soph.aub.edu|Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA. kkim@ms.soph.aub.edu|Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA. kkim@ms.soph.aub.edu