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

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.