Factors associated with non-publication of clinical trials in cardiovascular medicine: a cross-sectional analysis

Abstract Background/introduction Cardiovascular medicine is the fourth most-funded area of clinical research as it received an estimate for 7% of the total research funding. Nearly 8% of all clinical trials are cardiovascular-related (1,2). Non-publication of the registered clinical trials wastes money and time, encourages dissemination bias, and creates a body of possibly inaccurate literature, all of which obstruct scientific advancement. (3) Purpose To study the factors associated with the non-publication of cardiovascular clinical trials between January 2000 and June 2022. Methods We performed a cross-sectional analysis using ClinicalTrials.gov to determine all completed, discontinued, published, and unpublished cardiovascular medicine clinical trials between January 2000 and June 2022. For each trial, data on the trial phase, funding source, intervention type, enrolment size, trial completion, and publication status were extracted and subjected to logistic regression to determine clinical trial publication predictor factors. Results Among 3946 trials in cardiovascular medicine registered in ClinicalTrials.gov, there were 3215 completed trials included in the analysis. Of these, 34.2% (n=1100) were unpublished. On multivariate logistic regression, triple-blinded and quadruple-blinded trials were less likely to be unpublished compared to open-label trials (odds ratio [OR] 0.622; 95% confidence interval [CI] 0.45-0.85; p=0.003) and (OR 0.54; CI 0.42-0.69; p<0.001), respectively. Enrolment of 100 participants or more was associated with a decreased likelihood of non-publication (OR 0.46; CI 0.39-0.55; p<0.001). In addition, randomised trials were less likely to be unpublished than non-randomised trials (OR 0.67; CI 0.50-0.88; p=0.004). There was no significant effect of the intervention type, phase of the trial, trial participants' age and gender, or the trial funding resource on the publication status of cardiovascular medicine clinical trials. Conclusions It is observed that a considerable number of clinical trials in cardiovascular medicine remain unpublished. This issue raises some concerns regarding the risks and discomfort participants may encounter during the trial, while no results are added to the literature. Blinding of the trials, enrolment size, and allocation methods are the main predictors of trial publication.Forest plot of logistic regression