Treatments effects from randomized trials and propensity score analyses were similar in similar populations in an example from cardiac surgery.

OBJECTIVE

Analyses comparing randomized to nonrandomized clinical trials suffer from the fact that the study populations are usually different. We aimed for a comparison of randomized clinical trials (RCTs) and propensity score (PS) analyses in similar populations.

STUDY DESIGN AND SETTING

In a systematic review, we "meta-matched" RCTs and PS analyses that compared the off- and the on-pump technique in coronary artery bypass grafting. "Meta-confounders" were summarized in a "meta-propensity score" and were used for "meta-matching." We compared treatment effects between RCTs and PS analyses for 10 previously defined binary clinical outcomes in this "meta-matched" population as differences in "meta-odds ratios."

RESULTS

For all clinical outcomes, the estimated differences in "meta-odds ratios" were below an absolute value of 0.15, all confidence intervals included the null.

CONCLUSIONS

In our example, treatment effects of off-pump versus on-pump surgery from RCTs and PS analyses were very similar in a "meta-matched" population of studies, indicating that only a small remaining bias is present in PS analyses.