Understanding Nonadherence with Hydroxychloroquine Therapy in Systemic Lupus Erythematosus.

Objective: 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.

Methods: 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.

Results: 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.

Conclusion: 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.