Optimal frequency of visits for patients with Systemic Lupus Erythematosus to measure Disease Activity over time

Abstract

Objective: Adjusted mean Systemic Lupus Erythematosus Disease Activity Index (SLEDAI; AMS) measures lupus disease activity over time. Our aim was to determine optimal visit frequency for calculating AMS. Methods: Patients followed monthly for 12 consecutive visits were included. AMS was calculated using all of the SLEDAI 2000 (AMSGOLD using all 12 visits), only quarterly visits (AMS3, using visits 3 months apart), semiannual visits (AMS6, using first, middle, and last visits only), and annual visits (AMS12, using only the first and last visits). Comparisons of AMS3, AMS6, and AMS12 with AMSGOLD are made using descriptive statistics. Results: Seventy-eight patients were included (92% women, mean age at SLE diagnosis 30.1 yrs and at study start 46.2 yrs). The mean (SD) AMSGOLD for the entire year was 2.05 (1.66), for AMS3 1.99 (1.65), for AMS6 2.12 (1.87), and for AMS 12 2.08 (1.83). Mean (SD) of the absolute differences with AMS GOLD: for AMS3 0.29 (0.33), for AMS6 0.45 (0.59), and for AMS12 0.61 (0.58). Differences that were < 0.5 were considered minimal while those ≥ 1 were deemed important. Comparing AMSGOLD to AMS3, 82% of the differences were minimal and 3% were important. When comparing to AMS6, 68% were minimal and 10% were important, while comparing to AMS12, 50% were minimal and 21% were important. Conclusion: Usual clinic visits occurring quarterly offer a good estimation of disease activity over a 1-year period and are preferred over semiannual and annual visits.