How can we define low disease activity in systemic lupus erythematosus?

In recent years, low disease activity emerged as a state that is associated with improved long-term outcomes in systemic lupus erythematosus (SLE). Our aim was to review the current concepts for low disease activity in SLE in order to serve as the basis of a future consensus for standardization.

The PubMed database was searched for relevant articles from inception up to July 2018. Medical Subject Headings (MeSH terms) included "lupus" AND "low disease activity" OR "minimal disease activity".

Three different definitions of low disease activity in lupus have been proposed. Minimal disease activity (MDA) is defined as a clinical SLE Disease Activity Index 2000 (SLEDAI-2K)≤1 on antimalarials, immunosuppressives in standard doses and prednisone ≤5 mg/day. Low disease activity (LDA) allows for a clinical SLEDAI-2K≤2 maintained on antimalarials only. Lupus Low Disease Activity State (LLDAS) accepts a SLEDAI-2K≤4 with no activity from major organ systems, a Physician's Global Assessment of ≤1 with no new activity, prednisone dose ≤7.5 mg/day and standard doses of antimalarials, immunosuppressives and biologics. Active serology (anti-dsDNA and complement C3/C4) is not included in the MDA and LDA but counts towards disease activity in the LLDAS definition. All definitions were associated with less damage-accrual and mortality in the long-term that were comparable to those of clinical remission.

There is solid evidence that low disease activity is associated with improved outcomes in SLE and could serve as a therapeutic target in daily practice and clinical trials. Future research should focus on advancing a consensus for the best possible definition.