The relation between volume and outcome of coronary interventions: a systematic review and meta-analysis

Aims Although various studies reported better outcomes in centres performing a high volume of procedures of coronary artery bypass grafting (CABG) or percutaneous coronary interventions (PCIs), it is unclear how strong this relation is and whether it pertains to today's practice. Methods and results Medline, Embase, and conference reports were searched for studies reporting the effect of high volume of CABG or PCI on in-hospital mortality, adjusted for differences in case-mix. Of 140 potentially relevant papers, 15 were included, 2 of which reported data on both CABG and PCI. Meta-analysis of 10 studies on PCI, comprising 1 322 342 patients in 1746 hospitals, indicated an odds ratio (OR) of in-hospital mortality for patients treated in a high-volume hospital of 0.87 (95% confidence interval (CI) 0.83-0.91) compared to those treated in a low-volume hospital. The 7 CABG studies taken together, comprising 1 470 990 patients in 2040 hospitals, also revealed a significant effect of high volume (OR 0.85; CI 0.79-0.92). A differential effect for specific cut-off points could not be identified. Meta-regression did not show notable changes in the effect size over the years. Conclusions Patients undergoing CABG or PCI in a high-volume hospital exhibit lower in-hospital mortality than those treated at low-volume hospitals. Our meta-analysis does not support the view that this relation has attenuated over time.