Towards systematic prevention of athletics injuries : Use of clinical epidemiology for evidence-based injury prevention

The aims of this thesis were to outline the design protocol for a prospective clinical epidemiological study of injuries among athletics athletes; study the 1-year prevalence, the point prevalence and incidence of injuries in total cohorts of Swedish elite adult and talented youth athletics athletes; pinpoint the risk indicators and factors for different injury types/patterns in athletics. In paper I, an argument-based method to investigate complex design problems was used to structure the collection and analysis of data. A requirement analysis showed that a central requirement of an injury surveillance protocol for elite athletics should allow for detailed epidemiological analyses of overuse injuries, requiring self-reported data from athletes. The resulting study protocol was centred on a web-based weekly athlete e-diary enabling continuous collection of individual-level data on exposure and injuries. In paper II, the prevalence of injuries was examined and 278 athletes (87%) of the enrolled study population submitted their assessments via the web survey. The overall 1-year retrospective injury prevalence was 42.8% (95% CI 36.9–49.0%). The point prevalence of ongoing injury was 35.4% (95% CI 29.7–41.4%). The 1-year injury prevalence showed a tendency to vary with regard to gender and age (p = 0.11). The diagnostic group that displayed the highest 1-year prevalence (20.9%, 95% CI 16.2–22.2%) and point prevalence (23.2%, 95% CI 18.4–28.7%) of injury was inflammation and pain with gradual onset. In paper III, during the 52-week period, 292 athletes (91% of the study population) submitted weekly reports reporting a cumulative injury incidence of 3.57 injuries per 1000 hours of exposure to athletics. Most injuries (73%) were reported from training. There was a statistically significant difference with regard to gender and age in the proportion of athletes who avoided injury (P=0.043). Differences between event groups could not be statistically demonstrated (P=0.937). Ninety-six percent of the reported injuries were nontraumatic (associated with overuse). About every second injury (51%) was severe, causing a period of absence from normal training exceeding 3 weeks. Seventy-seven percent of the injuries occurred in lower extremities. In paper IV, 199 (68%) athletes reported an injury during the study year. The median time to first injury was 101 days (95% confidence interval (CI) 75–127). Univariate log-rank tests revealed risk differences with regard to athlete category (p = 0.046), serious injury (>3 weeks time loss) during the previous season (p = 0.039) and training load rank index (TLRI) (p = 0.019). Athletes in the third and fourth TLRI quartile had almost a twofold increased risk of injury compared to the first quartile. Youth male athletes with a previous serious injury had more than a fourfold increased risk of injury compared with youth females with no previous injury