Adherence to biological therapies in patients with rheumatoid arthritis: a retrospective cohort study

The advent of biologic disease-modifying antirheumatic drugs has dramatically changed the comprehensions of treatment and long-term prognosis in patients with rheumatoid arthritis. The potent therapeutic results can only be achieved if the patients adhere to prescribed medications. The objective of this study was to estimate the impact of age, gender, duration of the disease, concomitant Methotrexate therapy, prior exposure to biologic agents, disease activity, functional capacity, and health-related quality of life on adherence to biologic treatment among Bulgarian population with rheumatoid arthritis. This was a retrospective observational cohort study that included 179 patients. At the baseline visit and subsequent follow-up assessments at 6, 12, 24 and 36 months, patients were interviewed by a physician and underwent physical examinations. We monitored the changes in disease activity, functional capacity and health-related quality of life on each time point. Univariate and multivariate binary logistic regression was used to determine the prognostic value of possible predictors of treatment adherence. Our findings showed that only DAS28 score [odd ratio (OR) = 1.174; 95% CI 1.74-2.362] and HAQ score (OR 2.803; 95% CI 1.428-5.503) remained significant for the treatment adherence throughout the study period. The adherence to the biologic disease-modifying anti-rheumatic drugs among Bulgarian patients with rheumatoid arthritis is suboptimal. A multifaceted and comprehensive knowledge of the influencing factors can be useful for the development of different strategies that can improve treatment adherence.