The definitions of short-term parameters amongst trials are very heterogeneous wherein each trial has different definitions of partial and complete response, incorporating varying thresholds for proteinuria and serum creatinine (Cr) as well as urinary red blood cells (uRBCs) [2-4].
We performed a retrospective analysis on a cohort of SLE patients with LN followed prospectively at the Toronto Lupus Clinic in order to determine the predictive capabilities of Cr, 24-hour urine proteinuria (24H-P), and uRBCs with respect to good long-term renal outcome.
For this study we analyzed laboratory results including serum Cr, 24H-P, and uRBCs [12,13].
24H-P and uRBCs are recorded and scored in our database only if they are attributed to SLE activity.
The renal parameters (24H-P, Cr, and uRBCs) for each patient at 1 year after the diagnosis of LN were studied.
Receiver operating characteristic (ROC) curves were generated to examine the predictive power of 24H-P, Cr, and uRBCs (at 12 months) with respect to primary and secondary good long-term renal endpoints.
ROC Curves Analyses for Proteinuria, Serum Cr and uRBCs
All the ROC curves for uRBCs at year 1 indicate low accuracy with AUC 0.60 for uRBCs at year 1 and uRBCs percentage change from baseline to year 1 (Figure 3).
Figure 4 illustrates the AUC values for proteinuria, serum Cr, and uRBCs measured as the value at year 1, absolute change from baseline to year 1, and percent change between baseline and year.
Although uRBCs provide low accuracy in predicting long-term renal outcomes with AUC of 0.60 its utility as an endpoint in clinical trials should be determined carefully.