From study design and analysis to conclusion: new horizons for epidemiological rigor in sport medicine.

Everyone involved in the care of athletes and their well being recognizes the importance of injury prevention and treatment. With the era of evidence-based medicine upon us, one assumes that the data and their interpretation from current epidemiological studies will help us understand more about causation and prevention. However, variations in definitions, methodologies, and analyses amongst studies can lead to differences in results and conclusions obtained. It is therefore important to be aware of these differences when interpreting the literature. The objective of this thematic issue is to help sport medicine clinicians determine if the appropriate conclusions are made in a published study and to introduce sport medicine researchers to some of the newer epidemiological developments that have implications for study design and analysis. We have specifically chosen articles that cover 3 main areas of interest: how do we define injury, methods for surveillance studies, and interpreting the analyses. Defining injury is fundamental in the field of injury prevention, and one would think that a consensus would have already been reached. But it is not. This issue begins with a consensus statement on injury definitions from the Rugby Union. Because the overall risk for injury is related to the product of injury incidence and severity, Fuller suggests that one must also define recurrent injury, severity, and training and match exposures. His paper also provides criteria for classifying injuries in terms of location, type, diagnosis, and causation. Although there is consensus in the Rugby Union, areas for debate remain. One of the major issues still being discussed is whether an injury should be defined by time-loss or anatomical injury. We have therefore also included 2 articles (by Hodgson and colleagues, as well as Orchard and Hoskins) that debate this issue. In fact, each definition addresses different questions, and these articles will help clinicians determine if the most appropriate definition was used to answer the question posed by the authors and which study most closely addresses the clinician’s own question. In a second paper, Fuller and colleagues provide a strong rationale and a theoretical recording and reporting framework, suggesting the need for recording time-loss recurrent injuries and distinguishing between exacerbation of an existing injury and a true re-injury. Almost as fundamental as the general definition of injury is the method used to classify specific types of injuries. About 15 years ago, the Orchard Sports Injury Classification System (OSICS) was first described as a means to classify diagnoses and examine incidence of injury in Australian football players. The system has evolved over time, and OSICS-10 is presented herein by Rae and Orchard for clinicians and researchers interested in injury description and classification. One particular advantage of OSICS-10 is the ability to allow diagnoses to be quite specifically classified. For example, hamstring strains can now be retrieved by the traditional 1–3 grading system, which should permit greater accuracy and specificity for injury documentation. As an alternative approach, the Sport Medicine Diagnostic Coding System (SMDCS), first developed in 1991, is updated by Meeuwisse and Wiley and provides an interactive approach to injury documentation. A downloadable data file for both systems is provided that allows other groups to use the OSICS and SMDCS for their own purposes. In sports injury research, it is especially important to distinguish between incidence and prevalence. As applied to sports injury epidemiology, the prevalence of injury is the