Understanding Nonadherence with Hydroxychloroquine Therapy in Systemic Lupus Erythematosus

Hydroxychloroquine (HCQ) is a cornerstone to managing systemic lupus erythematosus (SLE), yet adherence to medication is poor. We sought to measure the association of adherence with 5 "dimensions of adherence" as articulated by the World Health Organization for chronic conditions: the patient's socioeconomic status, and patient-, condition-, therapy-, and healthcare system-related factors. Our longterm goal is to generate evidence to design effective interventions to increase adherence.

The retrospective cohort study included Kaiser Permanente Northern California patients ≥ 18 years old during 2006-2014, with SLE and ≥ 2 consecutive prescriptions for HCQ. Adherence was calculated from the medication possession ratio and dichotomized as < 80% versus ≥ 80%. Predictor variables were obtained from the electronic medical record and census data. We used multivariable logistic regression to estimate adjusted OR and 95% CI.

The study included 1956 patients. Only 58% of patients had adherence ≥ 80%. In adjusted analyses, socioeconomic variables did not predict adherence. Increasing age (65-89 yrs compared with ≤ 39 yrs: OR 1.44, 95% CI 1.07-1.93), white race (p < 0.05), and the number of rheumatology visits in the year before baseline (≥ 3 compared with 0 or 1: OR 1.47, 95% CI 1.18-1.83) were positively associated with adherence. The rheumatologist and medical center providing care were not associated with adherence.

At our setting, as in other settings, about half of patients with SLE were not adherent to HCQ therapy. Differences in adherence by race/ethnicity suggest the possibility of using tailored interventions to increase adherence. Qualitative research is needed to elucidate patient preferences for adherence support.