Background/Purpose: Remission is a desirable but not a common enough outcome in systemic lupus erythematosus (SLE) and therefore additional measures are needed to evaluate new therapies. Our aims were: 1. to define and identify a group of SLE patients with low disease activity (LDA) in a prospective cohort; 2. To examine whether the LDA group was similar to a remission group and whether these 2 groups were different from a high disease activity group (HDA) in short term outcomes.

Methods: The study population included patients with SLE who were followed according to a standard protocol from 1970 to 2015 and who had visits no more than 18 months apart. The LDA group was defined as Systemic Lupus Erythematosus Disease Activity Index (SLEDAI-2K) of 2 or less (with or without positive serology) based on the presence of only 1 clinical manifestation of: rash, alopecia, mucosal ulcers, pleurisy, pericarditis, fever, thrombocytopenia or leukopenia. The patients could be taking antimalarial, but not corticosteroids or immunosuppressives. The remission group was defined as inactive clinical manifestations while only antimalarials were allowed and the HDA group was defined as SLEDAI-2K>6. The minimal time for inclusion in each group was 1 year.  

Results: Of 620 patients with active disease who were seen during this period 80 (12.9%) patients fulfilled the criteria for LDA, 191 (30.8%) for remission and 349 (56.3%) for HDA. The LDA patients with positive serology (30 patients) were similar to the LDA patients without serology (50 patients) in baseline and prior disease manifestations, co-morbidities, treatments and in the distribution of the defined SLEDAI-2K items at baseline. After 2 years of follow-up, the LDA and remission groups were similar in their adjusted mean SLEDAI score (AMS), organ involvement (including central nervous system, vasculitis, renal and musculoskeletal), SLICC score, mortality and different treatments (Table 1). After 2 and 4 years of follow up, the HDA group had higher AMS, more major organ involvement, higher SLICC score, more mortality and was given more treatments compared to the LDA and remission groups. Further comparison according to these categories between the HDA group and a combined group of LDA and remission groups, showed the same trend of worse outcome and prognosis for the HDA group (Table 2).   

Conclusion: SLE patients with LDA were defined and identified in a large SLE cohort. The 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.