Efficacy of adding belimumab to hydroxychloroquine for patients with serologically active clinically quiescent in systemic lupus erythematosus: A retrospective study

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Objectives In systemic lupus erythematosus (SLE), a serologically active clinically quiescent (SACQ) state is defined as one in which high anti-DNA antibody levels or low complement levels persist, however, disease activity remains stable. Although treatment intensification is not recommended for the SACQ state under the Treat to Target strategy, SACQ has been reported to be a risk factor for flares. The present study aimed to evaluate the efficacy of adding belimumab (BLM) to hydroxychloroquine (HCQ), the standard treatment for SLE, for patients in the SACQ state. Methods Patients treated with BLM were defined as the exposure group and those who did not were defined as the control group. Propensity score analysis with inverse probability of treatment weighting was used to analyze outcomes. The primary outcome was analyzed using the Kaplan–Meier method to determine time-to-event achievement to reduce prednisolone (PSL) dose to 7.5 mg/day or 5 mg/day. Secondary outcomes were as follows: (1) time to flares, analyzed using the Kaplan–Meier method, and (2) difference in median PSL dose at the last observation, analyzed using the Mann–Whitney U-test. Results Of the 146 patients in the SACQ state who received HCQ, 27 were included in the exposure group and 107 in the control group. The primary outcome, time-to-event achievement to reduce PSL dose to 7.5 mg/day and 5 mg/day had an HR value of 1.21 (95% confidence interval (CI) 0.78–1.89, p = 0.396) and 1.19 (95% CI 0.74–1.89, p = 0.471) in the two groups, respectively, with no significant difference between the two groups. No significant differences were observed in other outcomes. Conclusions Adding BLM to HCQ in patients in the SACQ state did not demonstrate effects in preventing flares or reducing glucocorticoids (GC) dose.