1. a Center for Injury Sciences , University of Alabama at Birmingham , Birmingham , Alabama , USA
2. b Center for Injury Sciences and Section of Trauma, Burns, and Surgical Critical Care, Division of General Surgery, School of Medicine , University of Alabama at Birmingham , Birmingham , Alabama , USA
3. c Department of Epidemiology and International Health , Center for Injury Sciences, School of Public Health , University of Alabama at Birmingham , Birmingham , Alabama , USA
4. d Department of Surgery, School of Medicine , University of Alabama at Birmingham , Birmingham , Alabama , USA