Performance of systemic lupus erythematosus responder index for detecting clinician-rated responders in patients with active systemic lupus erythematosus.

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Disease activity measures in systemic lupus erythematosus (SLE) are critical tools for trial endpoints. We aimed to evaluate the performance of current treatment outcome measures in SLE. Individuals with active SLE with a clinical SLE Disease Activity Index-2000 (SLEDAI-2K) score of at least 4 were followed up for two or more visits and classified as responders and non-responders based on a physician's judgment of improvement. The treatment outcome measures including SLEDAI-2K responder index-50 (SRI-50), SLE responder index-4 (SRI-4), substituting SLEDAI-2K with SRI-50 in SRI-4 (SRI-4(50)), SLE Disease Activity Score (SLE-DAS) responder index (Δ ≥ 1.72) and the British Isles Lupus Assessment Group (BILAG)-based Composite Lupus Assessment (BICLA) were tested. The performance of those measures was shown by sensitivity, specificity, predictive value, positive likelihood ratio, accuracy, and agreement against a physician-rated improvement. Twenty-seven patients with active SLE were followed. The total cumulative pair of visits (baseline and follow up) was 48. The overall accuracies (95% confidence interval [CI]) of SRI-50, SRI-4, SRI-4(50), SLE-DAS, and BICLA for detecting responders in all patients were 72.9 (58.2-84.7), 75.0 (60.4-86.4), 72.9 (58.2-84.7), 75.0 (60.4-86.4), and 64.6 (49.5-77.8), respectively. Subgroup analyses of lupus nephritis (23 patients had a pair of visits) found the accuracies (95% CI) of SRI-50, SRI-4, SRI-4(50), SLE-DAS, and BICLA were 82.6 (61.2-95.0), 73.9 (51.6-89.8), 82.6 (61.2-95.0), 82.6 (61.2-95.0), and 78.3 (56.3-92.5), respectively. However, there were no significant differences between the groups (P > 0.05). SRI-4, SRI-50, SRI-4(50), SLE-DAS responder index, and BICLA demonstrated comparable abilities to identify clinician-rated responders in patients with active SLE and lupus nephritis.