A Novel Disease Activity Measure for Systemic Lupus Erythematosus

“There is a well-recognized, unmet need for a new disease activity measure for systemic lupus erythematosus (SLE),” says Luís Sousa Inês, MD, PhD. “Previously developed instruments have limited performance to accurately measure SLE disease activity, are too time-consuming to apply in clinical practice, or both. The most widely used instrument is the SLE Disease Activity Index (SLEDAI), but it fails to identify almost two-thirds of cases with a clinically meaningful improvement or worsening.”

For a study published in the Annals of the Rheumatic Diseases, Dr. Inês and colleagues sought to develop a new measure of SLE—the SLE Disease Activity Score (SLE-DAS)—with improved sensitivity to change compared with the SLEDAI, while being user-friendly and maintaining high specificity. “The SLE-DAS has core items measured continuously, including proteinuria, swollen joint count, leukopenia and thrombocytopenia,” says Dr. Inês. “It has just 17 items to score, compared with 24 in the SLEDAI, while incorporating all disease manifestations in SLEDAI and added items for hemolytic anemia, cardiopulmonary, and gastrointestinal involvement.”

The researchers analyzed patients with SLE from two tertiary care centers and scored disease activity at each visit using the Physician Global Assessment (PGA) and SLEDAI 2000 (SLEDAI-2K). SLE-DAS was highly correlated with PGA and SLEDAI-2K in a validation cohort. The optimal discriminative ΔSLE-DAS cut-off to detect a clinically meaningful change was 1.72. In the validation cohort, SLE-DAS showed a higher sensitivity than SLEDAI-2K (change ≥4) to detect a clinically meaningful improvement (89.5% vs 47.4%) or worsening (95.5% vs 59.1%), while maintaining similar specificities. SLE-DAS performed better in predicting damage accrual than SLEDAI-2K.

“The SLE-DAS provides a continuous score of SLE disease activity, much more sensitive to change than SLEDAI-2k, with optimal specificity and a better performance to predict damage accrual than SLEDAI-2k,” notes Dr. Inês. “Moreover, the collection of SLE-DAS items requires a clinical workup time similar to that of SLEDAI-2k.”