Predictors of Good Long-Term Renal Outcomes in Lupus Nephritis: Results from a Single Lupus Cohort

Abstract

This study aims to elucidate the predictive capabilities of proteinuria, serum creatinine (Cr), and urine RBCs (uRBCs) with respect to long-term renal outcomes in lupus nephritis (LN) in patients followed in clinic. Methods. A retrospective analysis was performed on patients with LN. We evaluated the ability of proteinuria, serum Cr, and uRBCs at 12 months to predict good long-term renal outcomes defined as serum Cr ≤ 100 mmol/L and kidney transplant/dialysis-free at the 7th year. Receiver operator characteristic curves were generated for proteinuria, serum Cr, and uRBCs to study their ability to predict good long-term outcomes and to identify their best cut-off. Descriptive statistics studied the pattern of change of proteinuria and serum Cr. Results. Proteinuria of 0.6 g/d and Cr of 83 mmol/L performed independently moderately well in predicting good long-term renal outcomes while uRBC was less accurate. Combining serum Cr to proteinuria gave a small increase in positive predictive value with a trade-off in sensitivity. Proteinuria changed within the first year whereas serum Cr changed until the 7th year. Conclusions. Both proteinuria and Cr predict good long-term renal outcomes in LN. Proteinuria's ability to change faster at 12 months makes it a favorable endpoint for clinical trials and research studies.

Figure 1

ROC curves for predictive value of proteinuria at 1 year for primary good long-term renal endpoints. Proteinuria at 1 year and percentage change from baseline to year 1 demonstrate departure from the line of unity, whereas absolute proteinuria from baseline to year 1 does not. In all ROC curves sensitivity is plotted on the y-axis against 1 − specificity on the x-axis.

Figure 2

ROC curves for predictive value of serum Cr at 1 year for primary good long-term renal endpoints. All the ROC curves for serum Cr demonstrate departure from unity with the best AUC of 0.82 for serum Cr value at year 1. Serum Cr 1 year and percentage change from baseline to year 1 demonstrate departure from the line of unity, whereas absolute proteinuria from baseline to year 1 does not.

Figure 3

ROC curves for predictive value of uRBCs at 1 year for primary good long-term renal endpoints. uRBCs at year 1 and uRBCs percentage change from baseline to year 1 demonstrate departure from the line of unity.

Figure 4

Comparison of the area under the curve (AUC) for proteinuria, uRBC, and serum Cr at 1 year quantified as the one year level, the change from baseline visit, and the percentage change from baseline.

Figure 5

Change in proteinuria during follow-up. After initiation of therapy at LN diagnosis, there is rapid decrease in 24H-P that remains relatively stable thereafter. LCLM lower confidence limit. UCLM upper confidence limit.

Figure 6

Change in serum Cr and eGFR during follow-up. After initiation of therapy at LN diagnosis, serum Cr and eGFR remain relatively unchanged until year 6.

Figure 7

ROC curves for predictive power of 24H-P at 1 year for primary renal outcomes in subgroup with baseline 24H-P ≥ 1 g/d.