Renal transplant outcomes and de novo donor-specific anti-human leukocyte antigen antibodies: a systematic review

Background. Pre-transplant donor-specific anti-human leukocyte antigen antibodies (DSAs) are known risk factors for acute rejection and reduced graft survival after kidney transplantation. DSAs may also develop de novo DSAs (dnDSAs) after transplantation but the clinical implications of these antibodies remain uncertain. Methods. We undertook a systematic review of observational studies that examined the association between dnDSAs and graft and patient outcomes (through August 2017) with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system of reporting used to assess the quality of evidence available. Results. Thirty-six studies involving 10 535 transplant recipients were eligible. There was moderate quality evidence that transplant recipients who developed dnDSAs had increased risks of acute antibody-mediated rejection (AMR) [relative risk (RR) 9.66; 95% confidence interval (CI) 6.79-13.73, 16 studies, n = 4174]. For all other outcomes, the evidence was low to very low due to moderate-high heterogeneity and low study quality (acute cellular rejection, RR 2.92; 95% CI 2.16-3.94, 22 studies, n = 4991, low-quality evidence; chronic AMR and transplant glomerulopathy RR 6.78; 95% CI 4.31-10.66, 3 studies, n = 1617, very low-quality evidence; and graft loss RR 4.95; 95% CI 3.81-6.43, 19 studies, n = 5473, low-quality evidence). Meta-regression indicated that deceased kidney donation (R-2 = 1.00, P < 0.001) and region of study conduction (R-2 = 0.50, P = 0.005) modified associations between dnDSAs and outcomes. Conclusions. dnDSAs are associated with increased risks of adverse graft and patient outcomes after kidney transplantation, but estimation uncertainty of the augmented risks exist due to limitations such as heterogeneity within the existing literature. Therapeutic interventions targeted to eliminate or prevent these antibodies evaluated in randomized controlled trials are needed to establish whether dnDSAs are causal to transplantation outcomes.