Medication adherence and persistence in the treatment of rheumatoid arthritis with adalimumab and etanercept. Six years of analysis

OBJECTIVE: The aim of this study was to evaluate medication adherence and persistence of patients treated with Etanercept and Adalimumab for Rheumatoid Arthritis, also giving economic evaluations on therapy costs for Received Daily Dose (RDD). MATERIALS AND METHODS: This retrospective study took into account 6 years from January 1, 2007 to December 31, 2012. Medication adherence was quantified utilizing the ratio between RDD and Prescribed Daily Dose (PDD). Persistence has been reckoned taking into account the actual days of therapy comparing posology with supplied dose. The persistence has been graphed according to Kaplan-Meier method. The cost per RDD was reckoned starting from the expense incurred by Pescara General Hospital. RESULTS: Medication adherence gave results in values between 0.88-0.97 for Etanercept and 0.83-0.90 for Adalimumab. The value of persistence was 100% for Etanercept and 90% for Adalimumab for the first year, and 70% for Etanercept and 80% for Adalimumab for the second year. In the 3rd year the persistence for Etanercept was 50% while for Adalimumab it was 60%. In the fourth year the persistence for Etanercept was 21% while for Adalimumab it was 27%. The statistical analysis was conducted using the Log rank test. The average cost per RDD was €32.97 for Etanercept and for Adalimumab it was €32.00 as an average of 6 years. CONCLUSION: The medication adherence was good for both Etanercept and Adalimumab. The rate of persistence decreased strictly in the fourth year of treatment. This data suggests the need for continuous monitoring of patients in treatment with TNF blockers.