Hydroxychloroquine Dose and Hospitalizations for Active Lupus.

OBJECTIVES: We sought to determine the impact of hydroxychloroquine (HCQ) dose on the risk of hospitalizations for systemic lupus erythematosus (SLE).

METHODS: We conducted a case-crossover study within an academic health system, including patients with SLE who used HCQ and had ≥ 1 hospitalization for active SLE between January 2011 and December 2021. Case periods ended in hospitalization for SLE, whereas control periods did not. The exposures were the average weight-based HCQ dose, categorized as ≤5 or >5 mg/kg/day, and non-weight-based HCQ dose, categorized as <400 or 400 mg/day, assessed during each 6-month case or control period. Odds ratios (OR) were calculated using conditional logistic regression and adjusted for prior disease activity, kidney function, glucocorticoid use and other immunosuppressant use.

RESULTS: Of 2,974 patients with SLE who used HCQ (mean age 36.5 years; 92% female), 584 had ≥1 hospitalization with primary discharge diagnosis of SLE. Of these, 122 had ≥1 hospitalization for active SLE while using HCQ and had ≥1 control period with HCQ use during the study period. Lower HCQ weight-based dose (≤5 vs. >5 mg/kg/day) and non-weight-based dose (<400 vs. 400 mg/day) were each associated with increased hospitalizations for active SLE (adjusted OR 4.20 [95% CI 1.45-12.19] and 3.39 [95% CI 1.31-8.81]).

CONCLUSIONS: The use of lower doses of HCQ was associated with an increased risk of hospitalizations for active SLE. Although the long-term risk of HCQ retinopathy must be acknowledged, this must be balanced with the short-term and cumulative risks of increased SLE activity.