Assessing the risk of angiotensin receptor blockers on major cardiovascular events: a systematic review and meta-analysis of randomized controlled trials

Agreement Between Mega-Trials and Smaller Trials: A Systematic Review and Meta-Research Analysis

Importance

Mega-trials can provide large-scale evidence on important questions.

Objective

To explore how the results of mega-trials compare with the meta-analysis results of trials with smaller sample sizes.

Data Sources

ClinicalTrials.gov was searched for mega-trials until January 2023. PubMed was searched until June 2023 for meta-analyses incorporating the results of the eligible mega-trials.

Study Selection

Mega-trials were eligible if they were noncluster nonvaccine randomized clinical trials, had a sample size over 10 000, and had a peer-reviewed meta-analysis publication presenting results for the primary outcome of the mega-trials and/or all-cause mortality.

Data Extraction and Synthesis

For each selected meta-analysis, we extracted results of smaller trials and mega-trials included in the summary effect estimate and combined them separately using random effects. These estimates were used to calculate the ratio of odds ratios (ROR) between mega-trials and smaller trials in each meta-analysis. Next, the RORs were combined using random effects. Risk of bias was extracted for each trial included in our analyses (or when not available, assessed only for mega-trials). Data analysis was conducted from January to June 2024.

Main Outcomes and Measures

The main outcomes were the summary ROR for the primary outcome and all-cause mortality between mega-trials and smaller trials. Sensitivity analyses were performed with respect to the year of publication, masking, weight, type of intervention, and specialty.

Results

Of 120 mega-trials identified, 41 showed a significant result for the primary outcome and 22 showed a significant result for all-cause mortality. In 35 comparisons of primary outcomes (including 85 point estimates from 69 unique mega-trials and 272 point estimates from smaller trials) and 26 comparisons of all-cause mortality (including 70 point estimates from 65 unique mega-trials and 267 point estimates from smaller trials), no difference existed between the outcomes of the mega-trials and smaller trials for primary outcome (ROR, 1.00; 95% CI, 0.97-1.04) nor for all-cause mortality (ROR, 1.00; 95% CI, 0.97-1.04). For the primary outcomes, smaller trials published before the mega-trials had more favorable results than the mega-trials (ROR, 1.05; 95% CI, 1.01-1.10) and subsequent smaller trials published after the mega-trials (ROR, 1.10; 95% CI, 1.04-1.18).

Conclusions and Relevance

In this meta-research analysis, meta-analyses of smaller studies showed overall comparable results with mega-trials, but smaller trials published before the mega-trials gave more favorable results than mega-trials. These findings suggest that mega-trials need to be performed more often given the relative low number of mega-trials found, their low significant rates, and the fact that smaller trials published prior to mega-trial report more beneficial results than mega-trials and subsequent smaller trials.

Chronic Use of Angiotensin Converting Enzyme Inhibitors and/or Angiotensin Receptor Blockers is Not Associated With Stroke After Noncardiac Surgery: A Retrospective Cohort Analysis

Background

Inhibition of the renin-angiotensin-aldosterone pathways reduces blood pressure and proliferation of vascular smooth muscles and may therefore reduce the risk of stroke. We tested the hypothesis that patients taking angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) for at least 6 months have fewer postoperative strokes after non-neurological, noncarotid, and noncardiac surgeries than those who do not.

Methods

We considered adults who had noncardiac surgery at the Cleveland Clinic between January 2005 and December 2017. After excluding neurological and carotid surgeries, we assessed the confounder-adjusted association between chronic use of ACEIs/ARBs (during 6 preoperative months) and the incidence of postoperative stroke using logistic regression models.

Results

Postoperative strokes occurred in 0.26% (27/10,449) of patients who were chronic ACEI/ARBs users and in 0.18% (112/62,771) of those who were not. There was no significant association between ACEI/ARB use and postoperative stroke, with an adjusted odds ratio of 1.15 (95% confidence interval [CI]: 0.91-1.44; P=0.24). Secondarily, there was no association between exposures to ACEIs and postoperative stroke, versus no such exposure (adjusted odds ratio 0.88, 95% CI: 0.65-1.19; P=0.33). Similarly, there was no association between exposure to ARBs and postoperative stroke, versus no such exposure (adjusted odds ratio 1.05, 95% CI: 0.75-1.48; P=0.75).

Conclusion

We did not detect an effect of chronic ACEI/ARB use on postoperative strokes in patients who had non-neurological, noncarotid and noncardiac surgery; however, power was extremely limited.