Incidence and Predictors of Biopsy Proven Acute Interstitial Nephritis (BPAIN) Post-Kidney Transplant.

Abstract

Background: Acute interstitial nephritis (AIN) is associated with poor outcomes following kidney transplant (KT). AIN has been attributed to drug exposure in the general population, although drug-induced AIN in the KT population has not been well characterized. Methods: This was a retrospective case-control study aimed to identify drug exposure associated with biopsy proven AIN (BPAIN) in KT recipients. Patients transplanted between 1/1/1999 and 9/30/2013 were included. Cases of BPAIN were identified by biopsy records, with biopsy date serving as incident date and the remaining patients served as controls. Drug exposure was identified through electronic records using a list of drugs associated with AIN. In those with BPAIN, exposure was manually verified to ensure exposure occurred prior to incident date. All other drug exposure was analyzed and defined as one or more days of drug use within the first post-transplant year. Results: A total of 2671 patients were included. Demographic characteristics were well matched between groups with regards to sex, race, and age at transplant. A total of 18 patients experienced BPAIN at a median of 83 days post-transplant. Allopurinol, PPIs, H2RAs, NSAIDs, PCNs, cephalosporins, carbapenems, fluoroquinolones, and sulfa drugs were included in the initial analysis. All 18 cases included exposure to at least one of these drugs. Only allopurinol was associated with a significantly higher rate of exposure in the BPAIN group, with 33% of AIN patients receiving allopurinol compared with only 12.9% of controls, p = 0.02. Risk of graft loss for those with BPAIN was significantly increased, HR 3.48 (95% CI 1.65 - 7.35).Figure: No Caption available.Conclusion: AIN confers a significant risk of graft failure, and associated drugs should be avoided whenever possible. Allopurinol use was seen in more cases of BPAIN than controls, and may present an increased AIN risk in KT recipients.