New-Onset Gout after Kidney Transplantation: Incidence, Risk Factors and Implications

BACKGROUND: Although cyclosporine use has been associated with an increased risk of new-onset gout after renal transplantation, the incidence and risk factors for new-onset gout have not been reported in the era of modern immunosuppression. METHODS: We conducted a retrospective cohort study of Medicare primary renal transplant patients reported in the United States Renal Data System (USRDS), using Medicare claims data to determine the incidence of new-onset gout. Cox regression analysis was used to calculate adjusted hazard ratios (AHR) for cyclosporine (including separate analysis of Neoral) compared directly with tacrolimus, for the risk of new-onset gout, adjusted for baseline demographic factors and posttransplant renal function. RESULTS: The cumulative incidence of new-onset gout was 7.6% at 3 years posttransplant. The following factors were independently associated with an increased risk of new-onset gout: use of Neoral (vs. tacrolimus, AHR 1.25, 95% CI 1.07-1.47) at discharge, recipient male sex (AHR 1.44, 95% CI 1.25-1.67), older age, higher body mass index, and more recent year of transplant. No other immunosuppressive medications were associated with new-onset gout. Diabetes was associated with a significantly lower risk of new-onset gout. The development of new-onset gout was independently associated with decreased patient survival (AHR 1.26, 95% CI 1.08-1.47) as well as death-censored graft survival. CONCLUSIONS: Cyclosporine is an independent risk factor for new-onset gout after transplantation. The incidence of new-onset gout appears to be increasing even while the use of cyclosporine is decreasing, and the development of new-onset gout was an independent predictor for death and graft loss in this population.