Risk Factors for Medical Withdrawals in United States Tennis Association Junior National Tennis Tournaments: A Descriptive Epidemiologic Study

Background:There have been no large-scale epidemiologic studies designed to determine the risk factors related to medical withdrawal in United States Tennis Association junior national tennis tournaments.Hypothesis:Risk of medical withdrawal will increase on the basis of cumulative match volume within a tournament.Methods:A retrospective, cross-sectional analysis was performed of data collected for every match of all 4 United States Tennis Association supernational tournaments (spring, summer, fall, winter) for the boys and girls divisions and for all age divisions (12, 14, 16, 18) during a single year (2005). Logistic regression analysis was performed to determine relative risk of all risk factors. Additional analysis was performed to determine the threshold (ie, match number) at which a player would substantially increase his or her risk of medical withdrawal.Results:A total of 28 336 match exposures were analyzed, with an even distribution with respect to sex and age. The total medical withdrawal rate ...