Baseline renal function severity predicts long-term end-stage kidney disease risk in newly diagnosed multiple myeloma with renal impairment

Background Renal impairment complicates 20–50% of newly diagnosed multiple myeloma (NDMM) and is associated with substantially increased risks of end-stage kidney disease (ESKD) and death. Whether baseline renal function severity retains prognostic value for long-term ESKD risk in this population remains uncertain. Objective To evaluate whether baseline renal function severity predicts long-term ESKD risk in NDMM with renal impairment. Methods We conducted a single-center retrospective cohort study of 100 patients with NDMM diagnosed between 2010 and 2018. The primary endpoint was progression to ESKD, analyzed using the Fine–Gray subdistribution hazards model with death as a competing event. Overall survival (OS) was assessed as a secondary endpoint. Renal response was evaluated as an exploratory endpoint restricted to patients with baseline eGFR < 50 mL/min/1.73 m 2 ( n = 29). Results Over a median follow-up of 21.05 months, 9 patients progressed to ESKD. The 5-year cumulative incidence of ESKD differed significantly across renal strata (Gray’s test, p = 0.014), reaching approximately 26% in the eGFR 15–29 group versus no events with preserved function. In the Fine-Gray model, baseline eGFR 15–29 mL/min/1.73 m 2 was independently associated with ESKD (sHR, 4.02; 95% CI, 1.12–14.49; p = 0.033). In exploratory analyses restricted to the 29 patients with baseline eGFR < 50 mL/min/1.73 m 2 , minor renal response (MR) or better was achieved in 51.7% (50% vs. 53.3%; p = 0.858) and was associated with improved OS ( p = 0.007), but not with renal survival ( p = 0.81). Conclusions Baseline renal function severity, particularly eGFR 15–29 mL/min/1.73 m 2 , predicts long-term ESKD risk in NDMM with renal impairment; whether renal response modifies the ESKD risk associated with baseline renal impairment remains unresolved and should be tested in larger prospective cohorts with prespecified landmark or time-dependent response analyses.