Objectives: The aim of our current study was to analyze whether the use of important measures of methodological quality and reporting of randomized clinical trials published in the field of cardiovascular disease research haschanged over time. A furtheraim was to investigate whether there was an improvement over time in the ability of these trials to provide a good estimate of the true intervention effect.
Methods: We conducted two searches in the Cochrane Central Register of Controlled Trials (CENTAL) database to identify randomized cardiovascular clinical trials published in either 2012 or 2017. Randomized clinical trials (RCTs) trials in cardiovascular disease research with adult participants were eligible to be included. We randomly selected 250 RCTs for publication years 2012 and 2017. Trial characteristics, data on measures of methodological quality, and reporting were extracted and the risk of bias for each trial was assessed.
Results: As compared to 2012, in 2017 there were significant improvements in the reporting of the presence of a data monitoring committee (42.0% in 2017 compared to 34.4% in 2012; p < 0.001), and a positive change in registering randomized cardiovascular disease research in clinical trial registries (78.4% in 2017 compared to 68.9% in 2012; p = 0.03). We also observed that significantly more RCTs reported sample size calculation (60.4% in 2017 compared to 49.6% in 2012; p < 0.01) in 2017 as compared to 2012. RCTs in 2017 were more likely to have a low overall risk of bias (RoB) than in 2012 (29.2% in 2017 compared to 21.2% in 2012; p < 0.01). However, fewer 2017 RCTs were rated low (50.8% compared to 65.6%; p < 0.001) risk for blinding of participants and personnel, for blinding of outcome assessors (82.4% compared to 90.8%; p < 0.001), and selective outcome reporting (62.8% compared to 80.0%; <0.001).
Conclusions: As compared to 2012, in 2017 there were significant improvements in some, but not all, the important measures of methodological quality. Although more trials in the field of cardiovascular disease research had a lower overall RoB in 2017, the improvement over time was not consistently perceived in all RoB domains.
Keywords: cardiovascular disease; data monitoring committee; randomized clinical trials; risk of bias; trial registration.