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J Sci Med Sport. 2011 Jul;14(4):287-92. doi: 10.1016/j.jsams.2011.02.007. Epub 2011 Mar 22.

The impact of adherence on sports injury prevention effect estimates in randomised controlled trials: looking beyond the CONSORT statement.

Author information

1
Department of Public and Occupational Health, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands. e.verhagen@vumc.nl

Abstract

OBJECTIVE:

To investigate estimated outcome effects of a sports injury prevention intervention when analysed by means of a per protocol (PP) analysis approach.

DESIGN:

Randomised controlled trial (RCT) involving 522 athletes who sustained a lateral ankle sprain allocated to either an intervention (received a preventive programme in addition to usual care) or control group who were followed prospectively for one year.

METHODS:

Secondary analysis of data relating to registered ankle sprain recurrences, exposure and adherence to the allocated intervention using a PP analysis approach.

RESULTS:

Twenty-three percent of the RCT intervention group indicated to have fully adhered with the neuromuscular training programme. A per protocol analysis only considering fully adherent athletes and control athletes, showed a Hazard Ratio of 0.18 (95% CI: 0.07-0.43). Significantly fewer recurrent ankle sprains were found in the fully adherent group compared to the group that was not adherent (relative risk = 0.63; 95% CI: 0.43-0.99).

CONCLUSIONS:

A PP analysis on fully adherent athletes versus control group athletes showed that the established intervention effect was over threefold higher compared to an earlier intention-to-treat based analysis approach. This shows that outcomes of intervention studies are heavily biased by adherence to the allocated intervention.

PMID:
21429793
DOI:
10.1016/j.jsams.2011.02.007
[Indexed for MEDLINE]

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