Hydroxychloroquine dose based on body weight for patients with SLE

Results from a retrospective observational study evaluating the effects of hydroxychloroquine (HCQ) dose based on actual body weight (ABW) in Japanese patients with systemic lupus erythematosus (SLE) were published in Rheumatology by Yamamoto et al. Endpoints included continuation rates, flare-free rates, efficacy, and adverse events (AEs) in the high-dose (HD; ≥5 mg/kg) and low-dose (LD; <5 mg/kg) groups. Subgroups consisted of Group 1 (patients who newly initiated HCQ; n = 182), Group 2 (patients who initiated HCQ ≥1 year after SLE diagnosis; n = 123), and Group 3 (patients from Group 2 who did not receive immunosuppressive therapy escalation after HCQ initiation; n = 104). 

Key data: Overall, 28.6% of patients in Group 1 discontinued HCQ. After inverse probability of treatment weighting (IPTW) adjustment, the 5-year discontinuation rates due to AEs were 18.9% vs 13.6% in the HD vs LD groups, respectively (p = 0.314). Flare-free rates at 3 years favored HD vs LD HCQ: 75.0% vs 60.7% (p = 0.239) in Group 2 and 79.2% vs 57.8% (p = 0.141) in Group 3. Each 0.2 mg/kg increase in HCQ dose reduced flare risk in Group 3 (hazard ratio [HR], 0.91; 95% confidence interval [CI], 0.84–0.99; p = 0.036). 

Key learning: A lower HCQ dose based on ABW may be associated with a higher risk of flare in patients with SLE, supporting the importance of ABW-based dosing while maintaining tolerability.