Objectives: To evaluate non-adherence to prescribed subcutaneous biologicals in rheumatoid arthritis (RA) patients in Spain.
Methods: ARCO (Study on Adherence of Rheumatoid Arthritis patients to SubCutaneous and Oral Drugs) was a multicentre, non-interventional retrospective study involving 42 rheumatology clinics from representative hospitals throughout Spain. The primary objective was to assess the percentage of patients (aged ≥18 years with an established RA diagnosis) with non-adherence to prescribed subcutaneous biologicals using clinical records and hospital pharmacy dispensing logs as the primary information sources. Adherence was assessed using the Medication Possession Ratio (MPR). Additionally, patients completed the Morisky-Green Medication Adherence Questionnaire.
Results: A total of 364 patients (77.5% females, mean age 54.9 years, median RA duration since diagnosis 7.8 years) were enrolled in ARCO. Non-adherence (MPR ≤80%) was reported in 52/363 evaluable patients (14.3%), and was lower in patients receiving initial monthly drug administration (6.4%) than with weekly (17.4%; p=0.034) or every two weeks (14.4%; p=0.102) administration. By multivariate analysis, non-adherence was positively associated with RA duration above the median and with using induction doses. Monthly administration, compared to weekly administration, was inversely associated with non-adherence. Age, gender, order of administration, and changes in the interval of administration, showed no association with non-adherence. Compared with the MPR, the Morisky-Green questionnaire performed poorly in detecting non-adherence.
Conclusions: Non-adherence to the prescribed subcutaneous biological drug occurred in 14.3% of patients with RA. Patients using the most convenient administration period (i.e. monthly) had better adherence than those using more frequent dosing schedules.