Background To compare the prognosis of SLE patients who achieve clinically quiescent following treatment, with or without serologically active.

Methods We categorized SLE patients from Lupus Clinic of Royal Thai Army (LUCRA) cohort based on disease activity status (DAS): serologically active clinically quiescent (SACQ), Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) without serological domain = 0, positivity of anti-dsDNA or low complement; serologically and clinically quiescent (SQCQ) patients, SLEDAI-2K = 0. Prednisolone ≤ 5 mg/day, immunosuppressive drugs and antimalarials were allowed. Those who were not in any remission definitions were defined as non-remission status. Outcomes included flare (any new clinical feature of the SLEDAI-2K) and increase in Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) overtime. Regression analysis models were constructed to identify predictors of the outcomes.

Results A total of 197 patients with SLE were evaluated between March 2017 and November 2022. Sixty-eight SACQ patients, 57 SQCQ patients, and 72 non-remission patients were identified. The mean ± SD of follow up was 4.79 ± 0.63 years. The percentage of flares over 3 years after achieving SACQ status was 50% versus 26.3% in SQCQ (p = 0.007), and over 5 years was 57.4% versus 35.1%, respectively (p = 0.013). However, the changes in SDI over 5 years were similar between SACQ, SQCQ, and non-remission patients (22.9%, 24.8%, and 21.5%, respectively), p= 0.87. In addition, multivariable analysis revealed that SACQ status was not independent risk factor for increasing flare event compared with SQCQ group when adjusting for confounding factors (HR 1.65; 95% CI:0.94–2.89; p=0.083).

Conclusions To attain serologically remission in patients with clinically quiescent SLE had similar effects on flare event and damage accrual compared to serologically active. This supports treating SLE with a treat-to-target strategy for achieving clinical remission, irrespectively of serological activity.