The orthopaedic trauma literature: an evaluation of statistically significant findings in orthopaedic trauma randomized trialsReport as inadecuate

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BMC Musculoskeletal Disorders

, 9:14

First Online: 29 January 2008Received: 06 September 2007Accepted: 29 January 2008


BackgroundEvidence-based medicine posits that health care research is founded upon clinically important differences in patient centered outcomes. Statistically significant differences between two treatments may not necessarily reflect a clinically important difference. We aimed to quantify the sample sizes and magnitude of treatment effects in a review of orthopaedic randomized trials with statistically significant findings.

MethodsWe conducted a comprehensive search PubMed, Cochrane for all randomized controlled trials between 1-1-95 to 12-31-04. Eligible studies include those that focused upon orthopaedic trauma. Baseline characteristics and treatment effects were abstracted by two reviewers. Briefly, for continuous outcome measures ie functional scores, we calculated effect sizes mean difference-standard deviation. Dichotomous variables ie infection, nonunion were summarized as absolute risk differences and relative risk reductions RRR. Effect sizes >0.80 and RRRs>50% were defined as large effects.

Using regression analysis we examined the association between the total number of outcome events and treatment effect dichotomous outcomes.

ResultsOur search yielded 433 randomized controlled trials RCTs, of which 76 RCTs with statistically significant findings on 184 outcomes 122 continuous-62 dichotomous outcomes met study eligibility criteria. The mean effect size across studies with continuous outcome variables was 1.7 95% confidence interval: 1.43–1.97. For dichotomous outcomes, the mean risk difference was 30% 95%confidence interval:24%–36% and the mean relative risk reduction was 61% 95% confidence interval: 55%–66%; range: 0%–97%. Fewer numbers of total outcome events in studies was strongly correlated with increasing magnitude of the treatment effect Pearson-s R = -0.70, p < 0.01. When adjusted for sample size, the number of outcome events revealed an independent association with the size of the treatment effect Odds ratio = 50, 95% confidence interval: 3.0–1000, p = 0.006.

ConclusionOur review suggests that statistically significant results in orthopaedic trials have the following implications-1 On average large risk reductions are reported 2 Large treatment effects >50% relative risk reduction are correlated with few number of total outcome events. Readers should interpret the results of such small trials with these issues in mind.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2474-9-14 contains supplementary material, which is available to authorized users.

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Author: Jinsil Sung - Judith Siegel - Paul Tornetta - Mohit Bhandari



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