Impact of Center Volume on Post Heart Transplant Survival

Abstract

Purpose Previous studies have shown reduced 1-year post-transplant survival in low volume centers. We aimed to evaluate impact of center volume on post heart transplant survival in recent era of streamlined care. Methods The United Network of Organ Sharing (UNOS) database was queried for patients aged ≥ 18 years undergoing heart transplant between 2007-2016. The database was then merged to 2010 US census data and CDC 2015 heart failure mortality data. Center volume was available in encrypted center codes and divided in terciles ( 22-high) after removing centers that did not transplant organs since 2014. The available data was then evaluated with a cox-regression model to identify impact of center volume, UNOS regions, adjusting for individual patient level factors. Kaplan-Meier curves were computed to evaluate survival differences in center volume by UNOS regions. Results There were 111 centers included in the final dataset. There were 23 low, 52 medium and 36 high volume centers that performed 1084 (5%), 7995 (35%) and 13520 (60%) heart transplants respectively. Low volume centers had equivalent survival to medium and high volume centers across all UNOS regions except region 10 (Figure 1). A cox-regression model adjusting for recipient and donor factors showed that high volume centers in regions 2 (HR=0.79 (0.67-0.94)), 4 (HR=0.65 (0.46-0.92)) and 10 (HR=0.44 (0.30-0.63)) had significantly better survival whereas in region 8 they had worse survival (HR=2.0 (1.2-3.4))(Figure 2). Conclusion Post heart transplant survival at low and medium volume centers across all UNOS regions is comparable to high volume centers except in regions 2, 4 and 10.