#1046 The impact of remission occurrence on long-term renal survival in IgA nephropathy

Abstract Background and Aims We sought to evaluate the impact of remission occurrence on long-term renal survival in IgA Nephropathy (IgAN). Method We conducted a retrospective study that enrolled 230 patients with biopsy-proven IgAN and at least 6 months of follow-up. Complete remission was defined as achievement of 24-h proteinuria reduction to less than 0.3 g/day at any time point during follow-up. Partial remission was defined as at least 50% reduction in 24-h proteinuria from baseline values and less than 1 g/day. The primary composite endpoint was the occurrence of an eGFR decline by at least 50%, progression to ESRD or death, whichever came first. Results The study cohort had a median age at biopsy of 41 years (IQR: 33–51), 67% being males. The median eGFR and 24-h proteinuria were 52 ml/min (IQR: 29–77) and 1.5 g/day (IQR: 0.8–3.2), respectively. During a median follow-up time of 44 months (IQR: 17–88.3), 3.91% of patients showed an eGFR decline by at least 50%, 27.8% progressed to ESRD, 1.74% died without CKD progression and 1.3% died after progressing to ESRD. In terms of remission occurrence, 35.2% and 23.1% of patients achieved either a complete or partial remission at any time during the follow-up period, respectively. Patients that achieved a complete remission had a better renal function at biopsy [eGFR, 74 ml/min (IQR: 53–95.5)], a lower proteinuria [0.82 g/day (IQR: 0.34–2)] and a lower prevalence of T1-2 score (21%) compared to those that achieved a partial remission [eGFR, 59 ml/min (IQR: 37–85); 24-h proteinuria, 1.5 g/day (IQR: 0.8–3.3); T1-2 score, 43.4%] or no remission [eGFR, 30.5 ml/min (IQR: 19.2–48); 24-h proteinuria, 2.2 g/day (IQR: 1.2–3.99); T1-2 score, 64.6%], respectively (P < 0.001 for all comparisons). By multivariate logistic regression analysis, a better renal function at biopsy (OR, 1.02 for 1 ml/min; 95% CI, 1.007–1.03) and absence of T2 score (T2 vs. T0 score: HR, 0.19; 95% CI, 0.04–0.92) were identified as independent predictors of complete remission occurrence. When evaluating the predictors of renal outcome, by multivariate Cox proportional hazards regression analysis, baseline eGFR (HR, 0.94 for 1 ml/min; 95%, 0.92–0.96), C2 score (HR, 3.22; 95% CI, 0.96–10.7) were independent predictors of the primary composite endpoint. In addition, the achievement of a complete remission during follow-up independently determined a 94% reduction in the risk of the primary composite endpoint (HR, 0.06; 95%CI, 0.01-0.25), while occurrence of a partial remission independently determined a 57% reduction in the risk of disease progression (HR, 0.43; 95% CI, 0.21–0.88). The time to an event was significantly longer for patients with complete remission [median, 138 months (IQR: 131–138)] compared to patients with partial remission [median, 102.4 months (IQR: 57.1–129.2)] or no remission [median, 29 months (IQR: 8.3–70.8)] (P < 0.001). Conclusion Our study confirmed that achievement of a complete or a partial remission significantly improved the long-term renal outcome of patients with IgAN.