Flare rates and factors determining flare occurrence in patients with systemic lupus erythematosus who achieved low disease activity or remission: results from a prospective cohort study

OBJECTIVE: To investigate the frequency and determinants of flare in Chinese patients with lupus, focusing on the effect of glucocorticoid (GC) tapering on flare in patients who achieved low disease activity or remission. METHODS: We collected baseline and follow-up data from all consecutive patients in a prospective lupus cohort between January 2017 and December 2020. We defined low disease activity using the lupus low disease activity status (LLDAS), applied the DORIS (Definitions of Remission in SLE) for remission criteria and then assessed flare using the SELENA-SLEDAI Flare Index. RESULTS: Among a total of 185 patients enrolled, 139 exhibited low disease activity or remission with a median follow-up of 29.8 (21.2–35.2) months. The flare rates after achievement of LLDAS, clinical remission and complete remission on treatment were 0.23, 0.12 and 0.1 per patient-year, respectively. In contrast, the flare rate of patients who never achieved remission or LLDAS was 0.49 per patient-year. In patients with LLDAS or remission achievement, multivariate Cox regression analysis showed that lower C3 level at the time of first achieving LLDAS or clinical remission was an independent predictive factor for subsequent flares. Kaplan-Meier curves showed a significantly lower flare-free survival during the subsequent follow-up in patients with GC withdrawal compared with those maintained on a low dose of prednisone (≤7.5 mg/day) (HR=6.94, 95% CI 1.86 to 25.86, p=0.004). However, no significant differences in flare were observed in patients maintained on different low doses of prednisone (>5 mg/day and ≤7.5 mg/day vs >2.5 mg/day and ≤5 mg/day vs >0 mg/day and ≤2.5 mg/day) (p=0.200). CONCLUSIONS: Target achievement significantly lowered the rate of subsequent flare, from the perspective of both stricter targets and longer period in targets. C3 level was a strong predictor of flare in patients who have achieved treatment targets. Although GC tapering to minimal doses was feasible, its withdrawal may accelerate the risk of recurrence.