Relationship Between Operator Volume and Long-Term Outcomes After Percutaneous Coronary Intervention

Abstract

Background: Although many studies show an inverse association between operator procedural volume and short-term adverse outcomes after percutaneous coronary intervention (PCI), the association between procedural volume and longer-term outcomes is unknown.

Methods: Using the National Cardiovascular Data Registry CathPCI registry data linked with Medicare claims data, we examined the association between operator PCI volume and long-term outcomes among patients ≥65 years of age. Operators were stratified by average annual PCI volume (counting PCIs performed in patients of all ages): low- (<50 PCIs), intermediate- (50-100), and high- (>100) volume operators. One-year unadjusted rates of death and major adverse coronary events (MACEs; defined as death, readmission for myocardial infarction, or unplanned coronary revascularization) were calculated with Kaplan-Meier methods. The proportional hazards assumption was not met, and risk-adjusted associations between operator volume and outcomes were calculated separately from the time of PCI to hospital discharge and from hospital discharge to 1-year follow-up.

Results: Between July 1, 2009, and December 31, 2014, 723 644 PCI procedures were performed by 8936 operators: 2553 high-, 2878 intermediate-, and 3505 low-volume operators. Compared with high- and intermediate-volume operators, low-volume operators more often performed emergency PCI, and their patients had fewer cardiovascular comorbidities. Over 1-year follow-up, 15.9% of patients treated by low-volume operators had a MACE compared with 16.9% of patients treated by high-volume operators ( P=0.004). After multivariable adjustment, intermediate- and high-volume operators had a significantly lower rate of in-hospital death than low-volume operators (odds ratio, 0.91; 95% CI, 0.86-0.96 for intermediate versus low; odds ratio, 0.79; 95% CI, 0.75-0.83 for high versus low). There were no significant differences in rates of MACEs, death, myocardial infarction, or unplanned revascularization between operator cohorts from hospital discharge to 1-year follow-up (adjusted hazard ratio for MACEs, 0.99; 95% CI, 0.96-1.01 for intermediate versus low; hazard ratio, 1.01; 95% CI, 0.99-1.04 for high versus low).

Conclusions: Unadjusted 1-year outcomes after PCI were worse for older adults treated by operators with higher annual volume; however, patients treated by these operators had more cardiovascular comorbidities. After risk adjustment, higher operator volume was associated with lower in-hospital mortality and no difference in postdischarge MACEs.

Keywords: morbidity; mortality; outcome assessment (health care); percutaneous coronary intervention; stents.

Figure 1:

Study flow PCI, percutaneous coronary intervention; CMS, Centers for Medicare and Medicaid Services; NPI, National Provider Identification. Low-volume operators performed < 50 PCIs/year; intermediate-volume operators performed 50–100 PCIs/year; high-volume operators performed > 100 PCIs/year

Figure 2:

1-year cumulative incidence of MACE by operator volume overall (A), in patients presenting with STEMI (B), UA/NSTEMI (C), and stable angina (D), and those undergoing PCI of chronic total occlusion (E), bifurcation (F), and left main (G) lesions MACE, major adverse cardiovascular events (all-cause death, readmission for myocardial infarction, unplanned revascularization); STEMI, ST segment elevation myocardial infarction; UA, unstable angina; NSTEMI, non-ST segment elevation myocardial infarction; CTO, chronic total occlusion. Operator volume defined as in Figure 1.

Figure 3:

1-year cumulative incidence of all-cause mortality by operator volume overall (A), in patients presenting with STEMI (B), UA/NSTEMI (C), and stable angina (D), and those undergoing PCI of chronic total occlusion (E), bifurcation (F), and left main (G) lesions All abbreviations as in Figure 2; operator volumes defined as in Figures 1 and 2.