Impact of Institutional and Operator Volume on Short-Term Outcomes of Percutaneous Coronary Intervention: A Report From the Japanese Nationwide Registry

Abstract

Objectives: The aim of this study was to assess the volume-outcome relationship for PCI within the nationwide registration system in Japan.

Background: The effect of site and operator case load for percutaneous coronary intervention (PCI) on outcomes has not been investigated thoroughly in non-Western regions.

Methods: In the present study, PCI procedural data recorded between January 2014 and December 2015 in the Japanese PCI registry, a nationwide registration system, were analyzed. Institutions and operators were categorized into deciles based on the number of PCIs performed per year. Odds ratios (ORs) for in-hospital mortality and the composite endpoint (in-hospital death and periprocedural complications) were estimated for each decile (with the lowest volume group as a reference group).

Results: A total of 323,322 PCIs (at 625 hospitals [median PCI cases/year: 216; quartiles: 121 to 332] by 4,211 operators [median PCI cases/year: 28; quartiles: 10 to 56]) were analyzed, of which 2,959 patients (0.9%) and 7,205 patients (2.2%) experienced in-hospital mortality and the composite endpoint after PCI, respectively. The adjusted risk for in-hospital mortality and the composite endpoint was significantly higher in hospitals included in the lowest decile (<150 PCIs/year); the risk remained consistently low across the remaining deciles. Contrastingly, no significant volume-outcome relationship was observed between operator volume and outcomes. A similar trend was observed when the analysis was confined to emergency/urgent PCI cases.

Conclusions: In contemporary Japanese PCI practice, lower institutional volume was related inversely to in-hospital outcomes, but the association of annual operator volume with outcomes was less clear.

Keywords: complication; in-hospital mortality; percutaneous coronary intervention; volume–outcome relationship.