Low-dose aspirin confers protection against acute cellular allograft rejection after primary liver transplantation

Abstract

This study investigated the effect of low-dose aspirin in primary adult liver transplantation (LT) on acute cellular rejection (ACR) as well as arterial patency rates. The use of low-dose aspirin after LT is practiced by many transplant centers to minimize the risk of hepatic artery thrombosis (HAT), although solid recommendations do not exist. However, aspirin also possesses potent anti-inflammatory properties and might mitigate inflammatory processes after LT, such as rejection. Therefore, we hypothesized that the use of aspirin after LT has a protective effect against ACR. This is an international, multicenter cohort study of primary adult deceased donor LT. The study included 17 high-volume LT centers and covered the 3-year period from 2013 to 2015 to allow a minimum 5-year follow-up. In this cohort of 2365 patients, prophylactic antiplatelet therapy with low-dose aspirin was administered in 1436 recipients (61%). The 1-year rejection-free survival rate was 89% in the aspirin group versus 82% in the no-aspirin group (hazard ratio [HR], 0.77; 95% confidence interval [CI], 0.63-0.94; p = 0.01). The 1-year primary arterial patency rates were 99% in the aspirin group and 96% in the no-aspirin group with an HR of 0.23 (95% CI, 0.13-0.40; p < 0.001). Low-dose aspirin was associated with a lower risk of ACR and HAT after LT, especially in the first vulnerable year after transplantation. Therefore, low-dose aspirin use after primary LT should be evaluated to protect the liver graft from ACR and to maintain arterial patency.

FIGURE 1

Stacked bar plots of center‐specific total case numbers and proportions of patients receiving low‐dose aspirin (black) versus no aspirin (white) after LT. Center‐specific aspirin use is displayed as percentage above each bar.

FIGURE 2

Kaplan–Meier curve plots of rejection‐free survival for (A) the entire rejection cohort (n = 420) including biopsy‐proven (n = 364) and clinically suspicious ACR (n = 56) and (B) only biopsy‐proven ACR, (C) graft survival, and (D) overall survival for the aspirin and no‐aspirin group. Survival groups were compared using the log‐rank (Mantel–Cox) test. (E) Forrest plot is shown displaying adjusted HRs with the 95% CIs for significant and nonsignificant risk factors. Squares represent the HR, and the horizontal bars extend from the lower to the upper limit of the 95% CI of the HR estimate. Bold text indicates parameters of statistical or nearly statistical significance.