Background/Purpose:

Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K) is one of the most commonly used disease activity indices in clinical practice and research but this index doesn’t account for severity within each descriptor. Moreover, in clinical trials, the use of standard of care (SoC), which includes glucocorticosteroid (GCS) often confounds trial results.

We developed and validated a novel lupus disease activity index, SLEDAI-2K GCS (SLEDAI-2KG), that describes disease activity while accounting for GCS 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. Furthermore, SLEDAI-2KG has a low administration burden and a simple scoring system similar to SLEDAI-2K.

We aimed to compare the performance of SLEDAI-2K and SGI in identifying responders in response to SoC.

Methods:

Patients seen between January 2011 and January 2014, at a single lupus centre, with active disease (SLEDAI-2K ≥6) and on prednisone ≥ 10 mg/day, and with follow up visits within 5-24 months were studied. Treatment was determined based on the judgment of the treating rheumatologist.

Response to SoC therapy, at first follow up visit, was assessed by SLEDAI-2K and SLEDAI-2KG. Responders were defined based on the decrease in SLEDAI-2K and SGI score by ≥4. The performance of SLEDAI-2K and SGI was also compared using different cut-off points; 5, 6 and 7. Descriptive analysis was used in the analysis.

Results:

111 patients met the inclusion criteria of the study and were further analyzed. Patients’ characteristics are represented in table 1. The mean age of the patients at baseline visit was 35.75 ± 11.51 years and the SLE duration was 9.02 ± 7.74. The mean follow-up to 1^st visit was 7.68 ± 2.95 months. Mean SLEDAI-2K and SLEDAI-2KG at baseline was 12.39 ± 6.03 and 17.08 ± 6.73 respectively. The mean prednisone dose at baseline was 22.94 ± 14.19 mg/day.

SLEDAI-2KG identified more responders at 6 months (92% vs. 84%) and at 12 months (89% vs. 76%) compared to SLEDAI-2K. SLEDAI-2KG also identified more responders with cut off points5, 6 and 7 (Table 2).

Conclusion:

The novel index, SLEDAI-2KG, is superior to SLEDAI-2K in identifying responders at 6 and 12 months accounting for steroid dose and thus adjusting for severity within each descriptor of SLEDAI-2K. SLEDAI-2KG has the ability to enhance analyses in clinical trials to differentiate between responders on minimal and moderate/large doses of GCS.