Role of Class I and Class II Panel Reactive Antibodies in Predicting Post-Heart Transplant Rejection and Survival in the Current Era.

Abstract

Introduction Patients with elevated panel reactive antibodies (PRA) have longer waitlist times and worse outcomes post-transplant. PRAs are now better characterized with newer detection techniques and are classified as Class I and Class II antibodies. The prognostic role of Class I and Class II antibodies is currently unknown. Hypothesis Elevated Class I and Class II may not have the same prognostic implications. Methods Retrospective analysis of data reported to UNOS/OPTN registry for heart transplants between 2004 and 2015 was performed. All patients over the age of 18 were included in the study. Patients with missing PRA data and those with prior heart transplantation were excluded. Impact of Class I and Class II antibodies on treated rejection at one year and overall long-term survival was evaluated. Results Our cohort consisted of 17, 460 patients; of these 75.1% were male and 24.9% female. The mean age at transplant was 52.8 ±12.6 years. Class I PRA was ≤25% in 15,816 (90.6%) patients and ˃25% in 1600 (9.2%) patients. Class II PRA was ≤ 25% in 16,266 (93.2%) and ˃ 25% in 1121 (6.4%) patients. Multivariate analysis based on predictors identified in univariate analysis showed that recipient age, gender, year of transplantation, HLA mismatch and Class 2 antibodies ˃ 25% were predictive of treated rejection at one year. Similar analysis showed that recipient age, donor age, ischemic time, year of transplantation and Class I antibodies ˃ 25% were predictive of long-term survival ( Figure 1 ). Of these, elevated Class I antibodies was the strongest predictor of mortality with a hazard ratio of 25%. Conclusions Elevated Class I and Class II antibodies impact outcomes very differently. While higher Class II antibodies are associated with increased treated rejection at one year, higher Class I antibodies are associated with increased long-term mortality.