Higher hydroxychloroquine dose based on actual body weight is associated with lower SLE flare risks while maintaining tolerability

OBJECTIVES: The effects of hydroxychloroquine (HCQ) dose based on actual body weight (ABW) on systemic lupus erythematosus (SLE) remain unclear. We investigated the effects of HCQ dose based on ABW of patients with SLE. METHODS: Patients were classified into ≥5 mg/kg ABW (high dose HD) and <5 mg/kg ABW (low dose LD) groups. Patient backgrounds were adjusted using inverse probability of treatment weighting method. The discontinuation rate owing to adverse events of overall cohort (group 1) was evaluated. Subgroups with a disease duration ≥1 year (group 2) and without additional immunosuppressive agents and biologics after HCQ initiation (group 3) were compared with evaluate flare-rates, prednisolone dose, and serological data. RESULTS: Among 182 patients in group 1, 60 (33%) comprised the HD group. Five-year discontinuation rates were 18.9% and 13.6% in the HD and LD groups, respectively (p= 0.314). Three-year flare-free rates in HD groups were higher than those in LD group: 75.0% (HD) vs 60.7% (LD) (p= 0.239) in group 2, and 79.2% (HD) vs 57.8% (LD) (p= 0.141) in group 3. In group 3, each 0.2 mg/kg increase in the HCQ dose reduced flares (hazard ratio, 0.91; 95% confidence interval: 0.84-0.99). CONCLUSION: No clear differences in efficacy and safety were observed between the HD and LD groups; however, a higher HCQ dose was associated with a reduced flare risk. Our findings suggest that a lower HCQ dose may be associated with a higher flare risk in patients with SLE, highlighting the importance of HCQ dose based on ABW.