Hydroxychloroquine in patients with systemic lupus erythematosus: how much is enough?

Objective: To assess the daily and weight-adjusted dosages of hydroxychloroquine (HCQ) and the effects on long-term remission in the Lupus-Cruces cohort.

Methods: Observational study of routine clinical care data. We selected inception patients treated with HCQ with at least 5 years of follow-up. Prolonged remission was achieved when patients fulfilled definitions of remission in systemic lupus erythematosus remission criteria in five consecutive yearly visits. The associations between the weight-adjusted dose of HCQ during 5 years and prolonged remission were analysed. We also investigated the associations between prednisone doses, immunosuppressives (IS) and other antimalarial use with HCQ doses.

Results: 150 inception patients fulfilled the inclusion criteria. The mean starting dose of HCQ was 206 mg/day. The mean weight-adjusted starting dose of HCQ was 3.1 mg/kg/day with no patients treated with doses ≥5 mg/kg/day. Treatment with HCQ was maintained during the whole 5-year follow-up time in 147 patients (98%). The mean dose of HCQ during the 5-year follow-up was 194.6 mg/day (2.9 mg/kg/day). 108 patients (72%) were in prolonged remission. The mean weight-adjusted dose of HCQ per patient did not differ between those who did and did not achieve prolonged remission (2.9 vs 3 mg/kg/day, p=0.5). The dose of prednisone per patient (mean 2.3 mg/day during the 5-year follow-up) did not differ according to the weight-adjusted dose of HCQ. The mean weight-adjusted HCQ dose during the whole follow-up was the same in patients treated or not with IS or with mepacrine.

Conclusions: With the use of HCQ at stable doses of 200 mg/day (or 3.0-3.5 mg/kg/day) as the background therapy in patients with systemic lupus erythematosus, the majority of patients achieved prolonged remission.