Efficacy and Safety of Hydroxychloroquine Therapy for Systemic Lupus Erythematosus Patients Depend on Administration Dose

OBJECTIVE: Hydroxychloroquine (HCQ) has been prescribed in Japan only relatively recently and is recommended for the treatment of skin lesions, arthritis and renal lesions according to the Japanese Guideline for the Management of systemic lupus erythematosus (SLE) (2019). However, the associations between the efficacy and safety and the HCQ dose in Japanese SLE patients remain unclear. We investigated the efficacy and safety of different HCQ doses in Japanese SLE patients with a low disease activity who were not receiving immunosuppressants. METHODS: The disease activity was evaluated using the SELENA-SLEDAI 2011 criteria, the Cutaneous Lupus Erythematous Disease Area and Severity Index (CLASI) and serum biomarkers. Safety was evaluated via the frequency of adverse events over a period of three months. RESULTS: We enrolled 61 SLE patients treated with HCQ and no additional immunosuppressive therapy for more than 3 months. HCQ was administered to 46 patients at the usual dose and to 15 cases at a lower than usual dose. Although the CLASI activity scores decreased significantly in both groups, the magnitude of this decrease was larger in the usual-dose HCQ group than in the low-dose HCQ group. SLEDAI scores and immunological activity were significantly improved only in the usual-dose HCQ group. In addition, changes in the serum complement levels in the usual-dose HCQ group were more dramatic than in the low-dose HCQ group six months after the initiation of HCQ administration. Adverse events were more frequent in the usual-dose HCQ group than in the low-dose HCQ group (30.4% and 13.3%, respectively). CONCLUSION: HCQ therapy is effective for maintenance therapy of SLE patients. The usual dose of HCQ may have some advantage in ameliorating low complement levels.