Chronic kidney disease trajectories in lupus nephritis: Is progression unavoidable?

Objective: To characterize trajectories of chronic kidney disease (CKD) in lupus nephritis (LN) and identify predictors of CKD progression. Methods: At diagnosis, patients were classified as having impaired kidney function (IKF; eGFR <60 mL/min/1.73 m(2),at diagnosis). At last follow-up, outcomes were defined as CKD (KDIGO stages 3-5), sustained complete renal response (CRR; eGFR >90 mL/min/1.73 m(2), proteinuria <150 mg/day, inactive urinary sediment for >3 years). Predictors of CKD were assessed using Cox regression analysis. Results: Among 260 patients, 77 (29.6%) had IKF. Over a median follow-up of 189 months (IQR 91.6-300.4), 13 (5%) died and 54 (20.7%) developed CKD. Of the remaining 206 patients, 74 (35.9%) achieved sustained CRR for a median of 110.5 months (IQR 66.7-190.7). CKD-free survival at 10 and 20 years was 76.2% and 63.7% in IKF patients versus 96.2% and 91.3% in those without IKF; corresponding rates were 93.5% and 82.4% in IKF patients who recovered eGFR >60 mL/min/1.73 m(2) at 1 year. Baseline IKF (HR:4.14; p = 0.001) and chronicity index (HR:1.20; p = 0.001) independently predicted CKD. When stratified by renal trajectory, patients with IKF who recovered kidney function at 1 year remained at higher risk than those with preserved baseline function (HR 3.23; p = 0.001), while chronicity index was no longer significant. Conclusions: Over long-term follow-up, one in five LN patients developed CKD, and one-third were in sustained CRR. Baseline IKF identifies a high-risk but heterogeneous group. Early recovery improves prognosis but does not fully offset the long-term risk associated with initial renal impairment.