Progression to dialysis within 36 months according to group (dFLC <50 or ≥50 mg/L) and renal stage. Kaplan-Meyer plots depict renal survival. (A) All patients with renal involvement. (B) All patients with renal involvement, stratified by renal stage. (C) Patients with renal involvement and an initial dFLC ≥50 mg/L, stratified by renal stage. (D) Patients with renal involvement and an initial dFLC <50 mg/L, stratified by renal stage.