The influence of institutional volume on the incidence of complications and their effect on mortality after heart transplantation

Abstract

Background: The aim of this study was to determine whether institutional volume influenced the effect of postoperative complications on short-term and long-term survival after orthotopic heart transplantation (OHT).

Methods: The United Network for Organ Sharing database was queried for adult patients (aged ≥18 years) undergoing OHT between 2000 and 2010. Average institutional volume was calculated during the study period and modeled as a categoric and as a continuous variable. Postoperative complications included rejection, dialysis dependence, infection, stroke, reoperation, and a composite event. Kaplan-Meier estimates and Cox regression modeling were performed for each complication to categorize the unadjusted and adjusted influence of institutional volume on survival.

Results: The analysis included 19,849 OHT recipients who were stratified into low-volume (≤14.5 per year), intermediate-volume (14.5-26.5 per year), and high-volume (>26.5 per year) tertiles. The overall incidences of postoperative complications were 10.2% for rejection, 7.8% for dialysis dependence, 12.0% for reoperation, 24.1% for infection, and 2.3% for stroke. Recipients in low-volume institutions experienced more complications after OHT than high-volume institutions (43.4% vs 36.2%; p < 0.001). Survival after the composite complication outcome was significantly worse at 90 days, 1 year, and 5 years in the low-volume cohort. After risk adjustment, low institutional volume (when modeled as a continuous and as a categoric variable) was also independently predictive of mortality at each time point. As expected, survival at 5 years in patients without a postoperative complication (81%; 95 confidence interval [CI], 80.0%-82.8%) was statistically greater (p < 0.001) than those with 1 (72.8%; 95% CI, 69.9%-75.5%), 2 (59.8%; 95% CI, 54.4%-64.8%), or 3 (39.9%; 95% CI, 31.6%-48.2%) complications.

Conclusions: Postoperative complications after OHT have a greater incidence and effect on short-term and long-term survival at low-volume institutions. Accordingly, best practice guidelines established at high-volume institutions could better equip lower-volume hospitals to manage these events in hopes of optimizing transplant outcomes.

Keywords: failure to rescue; heart transplantation survival; institutional volume; morbidity after heart transplantation; orthotopic heart transplantation.