Defining response in systemic lupus erythematosus: A study by the Systemic Lupus International Collaborating Clinics group

Objective. In a preliminary attempt to develop a drug responder index for patients with systemic lupus erythematosus (SLE), 2 validated disease activity instruments were studied for their responsiveness and compared to a physician visual analog scale (VAS) assessment of disease activity. We attempted to determine whether these validated instruments were useful components in characterizing response in the setting of a clinical trial. Methods. Eighty paper patients were assessed using the British Isles Lupus Assessment Group (BILAG) and Systemic Lupus Disease Activity Index (SLEDAI) and by physician's assessment of global activity. The cases were arranged in random order and divided into groups of 20 patients and each group was assessed by 20 lupus experts; change in disease activity was recorded at 3 and 6 months compared to baseline using a physician VAS. Results. Four different lupus experts assessed disease activity in all 80 patients at baseline and 3 and 6 months after initiation of therapy using the BILAG and SLEDAI instruments. BILAG and SLEDAI scores correlated well over time; however, in a regression analysis where average physician VAS were chosen as the outcome variable, a significant amount of variation in the average physician VAS not related to the SLEDAI and BILAG scores was noted. Conclusion. The physician VAS may be too blunt to assess response in SLE, because even among experienced lupus assessors, there were considerable differences in what influenced scoring decisions.