Hydroxychloroquine improves the disease activity and allows the reduction of the corticosteroid dose regardless of background treatment in Japanese patients with systemic lupus erythematosus

Objective Hydroxychloroquine (HCQ) was not approved in Japan until 2015, and its therapeutic potential has not been explored in depth. We evaluated the additional therapeutic effect of HCQ in Japanese patients with systemic lupus erythematosus (SLE) on maintenance therapy. Methods Patients with SLE who visited our hospital from 2015 to 2016 and were taking prednisolone (PSL) at <20 mg/day were retrospectively evaluated. All patients were divided into three groups according to their maintenance treatment regimen: PSL + immunosuppressant, PSL alone, and no treatment. We compared the changes in the SLE disease activity index (SLEDAI), PSL dose, and cumulative flare rate between patients who were and were not treated with HCQ. Results Among the 165 patients evaluated, 35 (21.2%) were treated with HCQ. The mean period of observation did not differ markedly between patients who did and did not receive HCQ (p=0.3). The SLEDAI and PSL dose were significantly reduced in patients who received HCQ, regardless of their background treatment regimen. The cumulative flare rate was lower in patients who received HCQ than in those who did not in the PSL + immunosuppressant and no maintenance treatment groups (p=0.03 and 0.05, respectively). Conclusion The addition of HCQ reduced the disease activity and allowed PSL dose reduction, regardless of background treatment, in Japanese patients with SLE.