Estimating unbiased sports injury rates: a compendium of injury rates calculated by athlete exposure and athlete at risk methods

A basic principle in epidemiology is that an injury rate should only include time when a person is ‘at risk’ for the outcome. However, when calculating injury rates in sports medicine, many investigators use a method known as ‘athlete- exposures’ (AE) which was originally proposed by the National Collegiate Athletic Association (NCAA) surveillance programme.1 The AE method overestimates game injury rates when compared with using individual player time as the AE method attributes a full exposure to those who do not play a full game.2 Another method of capturing player exposure to injury is called the athletes-at-risk (AAR) method.2 The AAR method follows proper epidemiological principles, provides results very similar to the individual player time method in most contexts, and is easier to calculate. While the AE method will most often underestimate injury rates, the amount of underestimation depends on the sport and context. Our previous publication2 discusses these concepts …