Efficacy of a movement control injury prevention programme in adult men’s community rugby union: a cluster randomised controlled trial

Abstract

BackgroundExercise programmes aimed at reducing injury have been shown to be efficacious for some non-collision sports, but evidence in adult men’s collision sports such as rugby union is lacking.ObjectiveTo evaluate the efficacy of a movement control injury prevention exercise programme for reducing match injuries in adult men’s community rugby union players.Methods856 clubs were invited to participate in this prospective cluster randomised (single-blind) controlled trial where clubs were the unit of randomisation. 81 volunteered and were randomly assigned (intervention/control). A 42-week exercise programme was followed throughout the season. The control programme reflected ‘normal practice’ exercises, whereas the intervention focused on proprioception, balance, cutting, landing and resistance exercises.Outcome measures were match injury incidence and burden for: (1) all ≥8 days time-loss injuries and (2) targeted (lower limb, shoulder, head and neck, excluding fractures and lacerations) ≥8 days time-loss injuries.ResultsPoisson regression identified no clear effects on overall injury outcomes. A likely beneficial difference in targeted injury incidence (rate ratio (RR), 90% CI=0.6, 0.4 to 1.0) was identified, with a 40% reduction in lower-limb incidence (RR, 90% CI=0.6, 0.4 to 1.0) and a 60% reduction in concussion incidence (RR, 90% CI=0.4, 0.2 to 0.7) in the intervention group. Comparison between arms for clubs with highest compliance (≥median compliance) demonstrated very likely beneficial 60% reductions in targeted injury incidence (RR, 90% CI=0.4, 0.2 to 0.8) and targeted injury burden (RR, 90% CI=0.4, 0.2 to 0.7).ConclusionsThe movement control injury prevention programme resulted in likely beneficial reductions in lower-limb injuries and concussion. Higher intervention compliance was associated with reduced targeted injury incidence and burden.

Some methodological issues in the design and analysis of cluster randomised trials

“…Attwood et al 5 however, mention that the sample size calculation was adjusted for a cluster coefficient (between-cluster coefficient of variation which is closely related to intracluster correlation coefficient) of 0.26. Also, they used generalised estimating equations along with a Pearson χ 2 scaling parameter to account for design effect.…”

“…The risk of random confounding is generally greater in cluster randomised trials than individual randomised trials as the number of clusters is often small 3. Both Hislop et al 4 and Attwood et al 5 papers presented the baseline characteristics of participants in table 1, but they did not adjust for non-negligible imbalances in some baseline characteristics in their analysis 9. Confusingly, Hislop et al 4 paper reported p values for baseline comparisons (some of which were significant at 5% level), a common misuse of p values in the randomised trial literature.…”

“…An extreme example is the study of Attwood et al 5 who reported that 19 out of 41 clubs in the intervention group and 21 out of 40 clubs in the control group did not provide outcome data. Hislop et al 4 paper reported more moderate drop out: 3 out of 20 schools in the intervention group and 6 out of 20 schools in the control group.…”

“…Other statistical adjustment methods for selection bias due to missing outcomes include multiple imputation and inverse probability weighting 1 12 13. Hislop et al 4 and Attwood et al 5 accounted for attrition in the sample size calculations, but they (and also Andersson et al 6) failed to adjust appropriately for selection bias due to attrition in their analysis. Attwood et al 5 mention using the last observation carried forward , a method well known to produce biased results 14…”

“…Attwood et al 5 reported median (IQR across clusters) of non-adherence percentage to exercise programmes for different weeks as 85% (62%–90%) and 83% (65%–92%) in the intervention and control groups, respectively. Andersson et al 6 paper reported a compliance rate of 53% in the intervention group.…”