Analysis of the appropriate dose of hydroxychloroquine in systemic lupus erythematosus in Japan.

Abstract

Objective: Recent SLE guidelines recommend using HCQ at < 5.0 mg/kg/day to reduce retinopathy risk but note that doses below this may increase flare risk, suggesting 5.0 mg/kg/day as ideal. Evidence is insufficient, especially among Japanese.

Method: We retrospectively analyzed 321 SLE patients treated with HCQ at Juntendo University Hospital between December 2015 and March 2019. They were divided into a low-dose group (< 5 mg/kg /day, n = 205) and a high-dose group (≥ 5 mg/kg /day, n = 116). This study compared side effect discontinuation rates, flare rates and treatment efficacy in Japanese SLE patients according to HCQ dosage, evaluating changes in SLEDAI, glucocorticoid dosage, complement activity, and anti-ds DNA antibody titer.

Results: 321 patients were followed for a median of 66 months. Side effect discontinuation rate was not significantly different. SLE flare rates were 5.4% in the low-dose group and 8.6% in the high-dose group, with no significant difference (P=0.170). While the high-dose group showed a trend toward better treatment efficacy for secondary outcomes, the differences were not statistically significant.

Conclusion: There was no significant difference in flare incidence based on HCQ dosage. In the maintenance phase of remission, a lower dosage may be sufficient. Keyword: Systemic lupus erythematosus(SLE);Hydroxychloroquine(HCQ);Efficacy; Appropriate dose; retrospective study; Japan.