What is the quality of reporting in weight loss intervention studies? A systematic review of randomized controlled trials

Background: Despite the large number of randomized controlled trials (RCTs) assessing weight loss interventions, no study has assessed the quality of reporting in these trials. Purpose: To assess the quality of reporting of RCTs of weight loss interventions and to identify predictors of reporting quality. Methods: The RCTs assessed were derived from a published systematic review of trials investigating the efficacy of weight loss interventions. For our study, two reviewers independently rated the quality of reporting in these trials, based on the Consolidated Standards for Reporting of Trials (CONSORT) Statement. We describe the quality of reporting using number (percent) of studies satisfying each of the 44 CONSORT criteria. We use generalized estimating equations (GEE) to fit a multivariable regression model to determine factors that are associated with the overall quality reporting score. Results: We assessed 63 RCTs, of which 25 were dietary-lifestyle trials, 22 were pharmacological trials and 16 were behavior-cognitive, exercise-lifestyle, or surgical trials. Less than half (46%) of the trials defined the primary outcome of the study; about 10% provided the description of the method of allocation concealment. Multivariable GEE results showed that the sample size, type of intervention (non-pharmacologic trials having lower scores than pharmacologic trials), and publication time relative to the CONSORT Statement publication in 1996 (publications after 1996 having higher scores) were strong predictors of the quality reporting score. Reporting a statistically significant result on the primary outcome was not significantly associated with the quality score. Conclusion: While the overall quality in reporting seemed to have improved since the publication of the revised CONSORT Statement in 1996, the reporting of some key methodologic aspects, such as clear description of primary outcome and method of allocation concealment, still requires improvements. Factors that are significantly associated with the overall quality reporting score can be used as surrogates in the review of protocols to enhance the quality of the final reports.