Are there mortality improvements with newer interventions in adult cardiac surgery? Evidence from 73 meta-analyses

BackgroundIn the last two decades, many new interventions have been introduced with the ultimate goal of improving overall postoperative outcomes after cardiac operations in adults. We aimed to assess how often randomized controlled trials (RCTs) in adult cardiac surgery found significant mortality benefits for newer interventions versus older ones, whether observed treatment effect estimates changed over time and whether RCTs and non-randomized observational studies gave similar results. MethodsWe searched journals likely to publish systematic reviews on adult cardiac surgery for meta-analyses of mortality outcomes and that included at least one RCT, with or without observational studies. Relative treatment effect sizes were evaluated overall, over time, and per study design. Results73 meta-analysis comparisons (824 study outcomes on mortality, 519 from RCTs, 305 from observational studies) were eligible. The median mortality effect size was 1.00, IQR 0.54-1.30 (1.00 among RCTs, 0.91 among observational studies, p=0.039). 4 RCTs and 6 observational studies reached p<0.005 favoring newer interventions. 2/73 meta-analyses reached p<0.005 favoring the newer interventions. Effect size for experimental interventions relative to controls did not change over time overall (p=0.64) or for RCTs (p=0.30), and there was a trend for increase in observational studies (p=0.027). In 34 meta-analyses with both RCTs (n=95) and observational studies (n=305), the median relative summary effect (summary effect in observational studies divided by summary effect in RCTs) was 0.87 (IQR, 0.55-1.29); meta-analysis of the relative summary effects yielded a summary of 0.93 (95% CI, 0.74-1.18). ConclusionsThe vast majority of newer interventions had no mortality differences over older ones both overall and in RCTs in particular, while benefits for newer interventions were reported more frequently in observational studies.