Background/Purpose: Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K) Glucocorticoid Index (SLEDAI-2KG) is a valid index able to measure disease activity while accounting for glucocorticoid (GC) dose SLEDAI-2KG has the same descriptors as SLEDAI-2K in addition to a new descriptor “GCs” with different weight scores based on the dose of GCs. We aimed to: 1) determine the best cut-off for SLEDAI-2KG in identifying responders, 2) compare the performance of SLEDAI-2K and SLEDAI-2KG in identifying responders.

Methods: Patients seen between January 1995 – April 2018, at a single lupus centre, with SLEDAI-2K ≥6 and on GC ≥ 5 mg/day at baseline, and follow-up visits at 3, 6 and 9 months were studied.

Response to SoC therapy, at follow up visits were assessed by SLEDAI-2K and SLEDAI-2KG. The weighted GC score is as follows: < 5mg/day = 0; 5 mg/day = 1; 7.5 mg/day = 2; 10-12.5 mg/day = 3; 15-17.5 mg/day = 4; 20-22.5 mg/day = 5; 25-30 mg/day = 6; 32.5-42.5 mg/day =7; ≥45 mg/day=8. The performances of SLEDAI-2K and SLEDAI-2KG were compared using different cut-off points; 4, 5 and 6. Descriptive statistics and McNemar’s tests for paired responses at the same time point and level were performed in the analysis. A sensitivity analysis was conducted for patients on GC ≥10 mg/day. To gain insight on the decrease of SLEDAI-2KG scores, we evaluated SLEDAI-2K scores and GCs weighted scores change on follow up visits.

Results: Of the 247 patients, 86.2% female, 47.9% Caucasian, 19.7% Black, 15.4% Asian, 17.0% other.  The mean age at SLE diagnosis was 31.0 ± 13.0 and mean age at baseline was 35.7 ± 13.4 years.  SLE duration was 9.02 ± 7.74 years. Mean SLEDAI-2K and SLEDAI-2KG at baseline was 13.8 ± 6.9 and 19.3 ± 7.8 respectively. The mean GC dose at baseline was 28.6 ± 19.7 mg/day.

The results confirmed that a cut-off of 5 is the best for SLEDAI-2KG in identifying responders and SLEDAI-2KG identified more responders at 3, 6 and 9 months in patients taking ≥5 mg and ≥10 mg/day of GCs (table 1).

The decrease in SLEDAI-2KG scores on follow-up is the result of decrease in the scores of its components SLEDAI-2K and GCs weighted scores. Figure 1 illustrates the mean SLEDAI-2KG scores and its component scores including both the SLEDAI-2K component and the weighted GC dose at baseline, 3, 6 and 9 months follow-up.

Conclusion: The cut-off 5 is the most appropriate to identify responders by SLEDAI-2KG. Also, SLEDAI-2KG, is superior to SLEDAI-2K in identifying responders at 3, 6 and 9 months in patients taking ≥5 and ≥10 mg/day of GCs. The decrease of SLEDAI-2KG scores resulted from the decrease of its components-SLEDAI-2K scores and the weighted scores of GC.