Uric acid as a risk factor for progression to chronic kidney disease in patients with lupus nephritis: results from the KORNET registry.

OBJECTIVES Little is known regarding the effect of hyperuricaemia on the progression of kidney function in patients with lupus nephritis (LN). Thus, we investigated the effect of uric acid (UA) on the long-term outcome of patients with biopsy-proven LN. METHODS Data were obtained from KORNET, a prospective longitudinal systemic lupus erythematosus registry in the Republic of Korea. All 137 patients with LN included in this study had undergone a kidney biopsy and were subsequently treated with immunosuppressants. The patients were divided into two groups: UA ≤7 mg/dL and >7 mg/dL; their sociodemographic, clinical, treatment-related data, and outcomes were compared. Cox-proportional regression analyses were performed to identify independent predictors of renal outcome in patients with LN. RESULTS Among the 137 patients, 37 (27.0%) had UA >7 mg/dL. This higher UA group included fewer women, but more patients with hypertension, proliferative type LN, and a chronicity index >12. The 24-h urinary protein excretion and the creatinine level were higher in this group; haemoglobin, platelet, and albumin levels were lower. During 85.0 months of follow-up, complete remission at 1 year was less frequent in the higher UA group, whereas chronic kidney disease (CKD) and end-stage renal disease were more prevalent. In the Cox proportional hazards regression analysis, UA >7 mg/dL was a signi cant predictor of progression to CKD in patients with LN (hazard ratio=2.437; p=0.020). CONCLUSIONS Our findings suggest that hyperuricaemia at LN onset is an independent risk factor that predicts the development of CKD in patients with LN.