Hydroxychloroquine Dose and Hospitalizations for Active Lupus

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

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 six-month case or control period. Odds ratios (ORs) were calculated using conditional logistic regression and adjusted for prior disease activity, kidney function, glucocorticoid use, and other immunosuppressant use.

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% confidence interval [CI] 1.45-12.19, and adjusted OR 3.39, 95% CI 1.31-8.81).

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.