Severe nonadherence to hydroxychloroquine for lupus may have adverse consequences

Among patients receiving hydroxychloroquine for systemic lupus erythematosus (SLE), severe nonadherence to medication poses increased risks of SLE flare in the following year, early damage, and 5-year mortality, according to data from the SLICC* Inception Cohort.

Of the 1,849 cohort participants, 660 (88 percent women) who had been prescribed hydroxychloroquine for at least 3 months were included in the analysis. Serum samples of the participants were collected and analysed. Severe nonadherence was defined as a serum hydroxychloroquine level <106 ng/mL or <53 ng/mL for medication doses of 400 or 200 mg/day, respectively.

Outcomes included the risk of a flare (Systemic Lupus Erythematosus Disease Activity Index 2000 increase ≥4 points, initiation of prednisone or immunosuppressive drugs, or new renal involvement), damage (first SLICC/American College of Rheumatology Damage Index [SDI] increase ≥1 point), and mortality. Logistic regression and Cox proportional hazard models were used to estimate associations.

The median serum hydroxychloroquine was 388 ng/mL, with 48 patients (7.3 percent) having severe hydroxychloroquine nonadherence. Severe nonadherence was independently associated with greater odds of flare (odds ratio, 3.38, 95 percent confidence interval [CI], 1.80–6.42) and an increase in the SDI within each of the first 3 years (3 years: hazard ratio [HR], 1.92, 95 percent CI, 1.05–3.50).

There were 11 deaths recorded within 5 years. Three of these deaths involved patients with severe nonadherence (crude HR, 5.41, 95 percent CI, 1.43–20.39).

*Systemic Lupus International Collaborating Clinics (SLICC) Inception Cohort is an international multicenter initiative (33 centers throughout 11 countries).