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

Objective: : Recent systemic lupus erythematosus (SLE) guidelines recommend using hydroxychloroquine (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 the Japanese.

Method: : We retrospectively analysed 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 Systemic Lupus Erythematosus Disease Activity Index, glucocorticoid dosage, complement activity, and anti-ds DNA antibody titer.

Results: : Three hundred and twenty-one patients were followed for a median of 66 months. The 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 = .170). While the high-dose group showed a trend towards 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.