Urja Lathia, Emmanuel M Ewara, Francois Nantel

Poor adherence to therapy increases the patient and societal burden and complexity of chronic diseases such as rheumatoid arthritis (RA). In the past 15 years, biologic disease-modifying anti-rheumatic drugs (DMARDs) have revolutionized the treatment of RA. However, little data are available on the impact of adherence to biologics on health care resources. The objective of the study was to determine the long-term health care resource utilization patterns of RA patients who were adherent to biologic DMARD therapy compared to RA patients who were non-adherent to biologic DMARD therapy in an Ontario population and to determine factors influencing adherence. Patients were identified from the Ontario RA Database that contains all RA patients in Ontario, Canada, identified since 1991. The study population included RA patients, aged 65+ years, with a prescription for a biologic DMARD between 2003 and 2013. Exclusion criteria included diagnosis of inflammatory bowel disease, psoriatic arthritis or psoriasis in the 5 years prior to the index date and discontinuation of biologic DMARD, defined as no subsequent prescription during the 12 months after the index date. Adherence was defined as a medication possession ratio of ≥0.8 measured as the proportion of days for which a patient had biologic treatment(s) over a defined follow-up period. Adherent patients were matched to non-adherent patients by propensity score matching. A total of 4,666 RA patients were identified, of whom 2,749 were deemed adherent and 1,917 non-adherent. The age (standard deviation) was 69.9 (5.46) years and 75% were female. Relative rates for resource use (physician visits, emergency visits, hospitalization, home care and rehabilitation) for the matched cohort were significantly lower (P⩽0.0001) in adherent patients. Non-adherent patients' use of oral prednisone (67%) was significantly higher (P⩽0.001) than that of the adherent cohort (56%). RA patients adherent to biologic therapy have lower health care resource use and lower steroid use compared to non-adherent patients.