Adherence to hydroxychloroquine in patients with systemic lupus: contrasting results and weak correlation between assessment tools.

ABSTRACT Objectives: Hydroxychloroquine (HCQ) is an anchor drug in the treatment of systemic lupus erythematosus (SLE). Adherence to HCQ is key for efficacy. Inaccurate evaluation of adherence could lead to non-justified switch to more expensive or less tolerated drugs. Methods: Severe non-adherence rate to HCQ was estimated in a sample of SLE patients during a routine visit using blood HCQ concentration Results: The study involved 158 patients (86.1% females) aged 42.2±12.6 years treated with HCQ for 9.6±6.9 years. Blood HCQ concentration (mean±standard deviation) was 1046±662 µg/L at visit 1 and 855±577 µg/L at visit 2. At visit 1, the non-adherence rate varied from 3.2% (blood HCQ level Conclusion: Blood HCQ concentration