Objective: This study investigates the influence of different aspects ofmethodologic quality on the conclusions of a systematic reviewconcerning treatments of acute lateral ankle sprain.

Method: A data set of a systematic review of 44 trials was used, of which 22 trialscould be included in this study. Quality assessment of the individualstudies was performed using the Delphi list. We calculated effectsizes of the main outcome measure in each study in order to evaluatethe relationship between overall quality scores and outcome. Next, weinvestigated the impact of design attributes on pooled effectsizes by subgroup analysis.

Results: The quality of most studies (82%) waslow; only 4 of 22 trials were of high quality. Studies with proper randomization and blinding procedure produce a slightly higher (not statistically significant) effectestimate compared to the other studies.

Conclusion: Previous research has suggested that methodologicallypoorly designed studies tend to over-estimate the effectestimate. Our study does not confirm these conclusions.