Reanalyses of Randomized Clinical Trials Yield Different Conclusions

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Reanalyses of Randomized Clinical Trials Yield Different Conclusions
Reanalyses of Randomized Clinical Trials Yield Different Conclusions

(HealthDay News) — More than one-third of the small number of reanalyses of randomized clinical trials have implied conclusions different from those of the original articles, according to a study published online in the Journal of the American Medical Association.

Shanil Ebrahim, PhD, from Stanford University in California, and colleagues characterized methodological and other differences between the original trial and reanalysis of randomized clinical trial (RCT) data. Thirty-seven reanalyses were identified in 36 published articles, of which five were performed by entirely independent authors.

The most frequent differences in reanalyses were in statistical or analytical approaches (18 reanalyses) and in definitions or measurements of outcomes of interest (12 reanalyses), the researchers found. 

The direction of effect was changed in four reanalyses, and the magnitude of treatment effect was altered in two; changes in statistical significance of the findings were noted in four reanalyses. 

Interpretations were different from that of the original article in 35% of reanalyses: 8% showing that different patients should be treated, 3% showing that fewer patients should be treated and 24% showing that more patients should be treated.

"Authors of confirmatory reanalyses may choose not to publish the results or, alternatively, They may have difficulty publishing their article because many journals may not consider it interesting. Thus, our observed estimate of different conclusions (35%) is probably an overestimate," the researchers wrote.


  1. Ebrahim S et al. JAMA. 2014;312(10):1024-1032.
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