Acute graft pyelonephritis in renal transplant recipients: incidence, risk factors and long-term outcome.

Background: The influence of acute graft pyelonephritis (AGPN) on graft outcome in renal transplant recipients still remains controversial.

Methods: We retrospectively analysed 189 patients (113 males; mean age: 49.7 ± 13.1 years) undergoing renal transplantation at the University Hospital 12 de Octubre (Madrid, Spain) from January 2002 to December 2004, with a minimum follow-up of 36 months. Factors associated with AGPN were assessed by logistic regression analysis. Long-term graft function was compared according to the occurrence of this complication during follow-up. 'Decline in renal graft function' was defined as the increase in serum creatinine (SC) levels > 0.33 mg/dL between Month 3 and Year 1 after transplantation.

Results: Nineteen patients (10.0%) were diagnosed with 25 episodes of AGPN (incidence rate: 4.4 episodes per 100 patient-years). The presence of glomerulonephritis as the underlying disease [odds ratio (OR) 4.2; 95% confidence interval (95%CI): 1.3-14.1] and the previous occurrence of two to five (OR 9.4; 95%CI: 1.5-56.8) or more than five episodes of asymptomatic bacteriuria after transplantation (OR 19.8; 95%CI: 2.4-160.2) emerged as independent predictors for AGPN. A near-significant association was found for cytomegalovirus infection (OR 4.2; 95%CI: 0.9-18.4), whereas receiving a single-kidney transplant (vs. double-kidney) showed a protective effect (OR 0.2; 95%CI: 0.0-0.8). During the 36-month follow-up, levels of SC, creatinine clearance and 24-h proteinuria did not differ significantly between patients with or without AGPN, and this complication did not exert any effect on the risk for decline in renal graft function.

Conclusions: AGPN does not impair long-term graft function in renal transplant recipients.