Comparison of three different definitions of low disease activity in patients with systemic lupus erythematosus and their prognostic utilities

Objectives Three definitions of low-level disease activity in patients with SLE have been proposed by different groups. These include minimal disease activity (MDA), low disease activity (LDA) and the lupus low disease activity state (LLDAS). We investigated the performance of these definitions in SLE patients. Methods We recruited 299 SLE patients who were followed up annually for 4 consecutive years. We compared the three definitions of low disease activity via longitudinal analysis; we used a generalized, linear-mixed effects model and generalized estimating equations. Results The LLDAS was significantly associated with a lower SLICC/ACR damage index (beta coefficient=-0.064, 95% CI: -0.129, -0.002, P=0.050), reduced flare (odds ratio = 0.090, 95% CI: 0.034, 0.239, P<0.001), an improved SF-36 physical component score (beta coefficient=0.782, 95% CI: 0.046, 1.519, P=0.037), and an improved SF-36 mental component score (beta coefficient=1.522, 95% CI: 0.496, 2.547, P=0.004). Neither the MDA nor the LDA were associated with these variables. Conclusion The LLDAS definition performs better than the MDA and LDA definitions, showing that LLDAS is associated with less organ damage and flare, and a better quality of life, during follow-up.