Association of center volume with outcome after liver and kidney transplantation

Outcomes for certain surgical procedures have been linked with volume: hospitals performing a high number of procedures demonstrate better outcomes than do low-volume centers. This study examines the effect of volume on hepatic and renal transplant outcomes. Data from the Scientific Registry of Transplant Recipients were analyzed for transplants performed from 1996-2000. Transplant centers were assigned to volume quartiles (kidney) or terciles (liver). Logistic regression models, adjusted for clinical characteristics and transplant center clustering, demonstrate the effect of transplant center volume quantile on 1-year post-transplant patient mortality (liver) and graft loss (kidney). The unadjusted rate of renal graft loss within 1 year was significantly lower at high volume centers (8.6%) compared with very low (9.6%), low (9.9%) and medium (9.7%) volume centers (p=0.0014). After adjustment, kidney transplant at very low [adjusted odds ratio (AOR) 1.22; p=0.043) and low volume (AOR 1.22 p=0.041) centers was associated with a higher incidence of graft loss when compared with high volume centers. Unadjusted 1-year mortality rates for liver transplant were significantly different at high (15.9%) vs. low (16.9%) or medium (14.7%) volume centers. After adjustment, low volume centers were associated with a significantly higher risk of death (AOR 1.30; p=0.0036). There is considerable variability in the range of failure between quantiles after kidney and liver transplant. Transplant outcomes are better at high volume centers; however, there is no clear minimal threshold volume.