Serum Albumin as an Early Predictor of Proteinuria Recovery in Lupus Nephritis

Proteinuria, a slowly changing marker, is considered the best predictor of long-term renal outcomes in lupus nephritis (LN). In this study, we aimed to determine if serum albumin can serve as an early predictor of combined proteinuria recovery in LN. We studied patients diagnosed with LN with baseline and follow-up visits at 6-9 and 18-21 months. Receiver operating characteristic (ROC) curves were generated and the area under the curve (AUC) was analysed at different time points to test if serum albumin was a predictor of combined proteinuria recovery response (complete and partial proteinuria recovery, CPR+PPR) and primary efficacy proteinuria recovery (PEPR) at 6-9 and 18-21 months. ROC curves for serum albumin level at baseline did not predict combined proteinuria recovery or PEPR at 6-9 or 18-21 months. However, serum albumin level at 6-9 months predicted combined proteinuria recovery at 6-9 months (AUC 0.77) and PEPR at 6-9 (AUC 0.83) and 18-21 months (AUC 0.83). Serum albumin absolute change (AUC=0.82) and percent change (AUC=0.81) from baseline to 6-9 months predicted the 6-9-month combined proteinuria recovery. Similarly, serum albumin absolute change (AUC=0.84) and percent change (AUC=0.82) from baseline to 18-21 months predicted the 18-21-month combined proteinuria recovery. A less pronounced, but similar signal was observed when PEPR was used as the endpoint at 6-9 (AUC 0.70 and 0.68, respectively) and 18-21 months (AUC 0.73 and 0.71, respectively). Serum albumin may serve as an accessible adjunct to proteinuria in assessing the clinical course and treatment response in LN.