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

Background/Purpose: 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. Methods: 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. Results: 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). Conclusion: Serum albumin may serve as an accessible adjunct to proteinuria in assessing the clinical course and treatment response in LN.