Identification of patients at risk of non-adherence to oral antirheumatic drugs in rheumatoid arthritis using the Compliance Questionnaire in Rheumatology: an ARCO sub-study

The ARCO study (Study on Adherence of Rheumatoid Arthritis patients to SubCutaneous and Oral Drugs), a multicenter, non-interventional retrospective study, was primarily designed to assess the percentage of patients [aged ≥18 years with an established rheumatoid arthritis (RA) diagnosis] with non-adherence to prescribed subcutaneous biologicals. This paper reports data for the secondary objective from a subset of patients, namely to evaluate non-adherence to prescribed oral antirheumatic drugs in RA patients in Spain using the validated Compliance Questionnaire Rheumatology (CQR). Patients also completed the Morisky–Green Medication Adherence Questionnaire, Beliefs about Medicines Questionnaire, and a questionnaire (developed and validated in Spain) on patient satisfaction with RA treatment and preferences. A total of 271 patients (76.7% females; mean age 55.6 years) were being treated with oral drugs for RA, of which 234 completed the CQR questionnaire. Non-adherence was reported in 49/234 (20.9%) patients. The proportion of non-adherence in younger patients (aged ≤48 years; 37.5%) was double that recorded in patients aged >48 years (p = 0.006). Patients with a perception of lower efficacy also had a higher risk of non-adherence (p = 0.012). Multivariable analysis showed that younger age and male gender were independently associated with risk of non-adherence. There was only slight agreement between the CQR and Morisky–Green assessment tools (kappa coefficient = 0.186), possibly reflecting the fact that both questionnaires measure slightly different aspects of medication adherence. In conclusion, one out of five RA patients was identified as at risk for non-adherence with the CQR, and this was more frequent in younger patients and in males.