MO216: The Importance of Nephrotic Range Proteinuria in Renal Survival of Patients With IGA Nephropathy

Abstract

Abstract BACKGROUND AND AIMS Persistent proteinuria (urinary protein level [UPr]>1 g/24 h) and especially nephrotic range proteinuria, is a poor prognostic factor in IgA nephropathy. Patients with proteinuria > 3.5 g/24 h have a 24-fold faster decline of renal function as compared with those with < 1g/24 h. The aim of this study was to explore the relationship between nephrotic range proteinuria and renal survival in patients with IgA nephropathy. METHOD All records from patients who were followed in a renal outpatient clinic and had a biopsy-proven IgA nephropathy were retrospectively screened. Patients with nephrotic range proteinuria (UPr > 3.5 g/24 h) at the time of diagnosis were compared, regarding their clinical and epidemiological characteristics, with patients with lower levels of proteinuria. Renal survival was defined as the absence of end-stage kidney disease [estimated Glomerular Filtration Rate (eGFR)≤15 mL/min/1.73 m2] or/and a ≥ 50% reduction of eGFR from baseline values. RESULTS We included 53 patients with IgA nephropathy. Their mean age was 46.24 (±16.92) and the median follow-up time was 49 (17–111) months. The median UPr value at the time of diagnosis was 1.89 (0.83–3.50) g/24 h and 17 patients had UPr > 3.5 g/24 h. Patients with nephrotic range proteinuria had worse renal function (eGFR 29 versus 73 mL/min/1.73 m2 P < .001), developed more frequently hypertension (82.35% versus 50%, P = .02) and rapidly progressive glomerulonephritis (23.53% versus 5.56%, P = .05) compared with those with lower levels of proteinuria. The episodes of macroscopic hematuria were less frequent in the group of patients with nephrotic range proteinuria (11.76% versus 38.89%, P = .05). Regarding patients treated with prednisone, the mean daily dose of prednisone was 23.42 mg for the nephrotic patients versus 16.61 mg for the patients with UPr < 3.5 g/24 h (P = .03). Proteinuria > 3.5 g/24 h was an independent risk factor for poor renal survival (HR 15.48, P = .01). The 5-year renal survival of patients with nephrotic range proteinuria was reduced compared with those with lower levels of proteinuria (66.64% versus 100%). CONCLUSION This study showed that the presence of nephrotic range proteinuria at the time of diagnosis was an independent risk factor for reduced renal survival. This relationship persisted after sex, age and renal function adjustment at the time of diagnosis.