How well is the clinical importance of study results reported? An assessment of randomized controlled trials

Background: The interpretation of the results of randomized controlled tria ls (RCTs) has traditionally emphasized statistical significance rather than clinical importance. Our aim was to assess the quality of reporting of fac tors related to clinical importance in a sample of published RCTs. Methods: A random sample of 27 (of a total of 266) RCTs published in 5 majo r medical journals over a 1-year period were reviewed by 4 independent revi ewers for factors considered important in the interpretation of the clinica l importance of study results: identification of a clearly defined primary outcome, reporting of the expected difference between groups used in the ca lculation of sample size (the delta value) and whether it was based on the minimal clinically important difference of the intervention, the statistica l significance of the results, presentation of pertinent confidence interva ls, and the authors' interpretation of the clinical importance of the resul ts. Results: Twenty-two of 27 (81%) articles explicitly reported a single prima ry outcome. Of the 20 articles that included a sample size calculation, 18 (90%) reported a delta value. Two of the 18 (11%) articles explicitly state d that the delta value was chosen to reflect the minimal clinically importa nt difference of the intervention. For the primary outcomes, confidence int ervals surrounding the point estimates of the efficacy of the interventions were reported in 11 of 27 (41%) studies. The study results were interprete d from the perspective of clinical importance in 20 of 27 (74%) of the arti cles. Of these 20 reports, 5 (25%) provided justification for their clinica l interpretation of the results. Interpretation: Authors of RCTs published in major general medical and inte rnal medicine journals do not consistently provide their own interpretation of the clinical importance of their results, and they often do not provide sufficient information to allow readers to make their own interpretation.