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.