Defining Low Disease Activity in Systemic Lupus Erythematosus

Objective. To define and identify a group of systemic lupus erythematosus patients with low disease activity (LDA) and to examine whether LDA is similar to patients in remission and different from a high disease activity group (HDA) in short-term outcomes. Methods. The LDA group was defined as Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) <3, including only 1 clinical manifestation of rash, alopecia, mucosal ulcers, pleurisy, pericarditis, fever, thrombocytopenia, or leukopenia. The patients could be taking antimalarials. Remission was defined as no clinical manifestation from taking antimalarials alone, and the HDA group was defined as SLEDAI-2K>6. The time frame for inclusion in each group was at least 1 year. Results. Of 620 patients with active disease who were seen between 1970 and 2015, 80 patients (12.9%) fulfilled the criteria for LDA, 191 (30.8%) for remission, and 349 (56.3%) for HDA. The LDA patients with and without positive serology results were similar at baseline and with prior disease characteristics. After 2 years of followup, the LDA and remission groups were similar in their adjusted mean SLEDAI-2K score, organ involvement, The Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) score, mortality, and therapies. After 2 and 4 years of followup, the HDA group had a higher adjusted mean SLEDAI-2K score, more major organ involvement, a higher SDI score, higher mortality, and more therapy compared to the combined LDA/remission groups. Conclusion. LDA and remission groups had similar short-term outcomes, and both had better outcomes and prognosis than the HDA group. LDA may be used as an outcome measure in therapeutic trials or in treat-to-target regimens.