Medication Adherence, Persistence and Cost in Multiple Sclerosis Patients: Oral vs Parenteral Treatment

Abstract

The primary purpose of this study was to evaluate the medication adherence of MS patients to oral and parenteral self-administration therapy. The secondary outcome was to study how the adherence varies respect of the length of treatment and calculate the daily cost of therapy. The adherence was evaluated by the ratio between the Received Daily Dose (RDD) and the Prescribed Daily Dose (PDD); the persistence to treatment was plotted with the Kaplan Meier method. The daily cost of theraphy was calculated as cost per RDD. The adherence in function of time was calculated using 30 days intervals. The average adherence values were 0.91 for Avonex, 0.81 for Rebif®, 0.83 for Betaferon®, 0.81 for Extavia®, 0.90 for Copaxone®, 0.89 for Gilenya®, 0.83 for Aubagio®. The persistence on 3 years of therapy was 64% for Rebif®, 62% for Betaferon®, 58% for Gilenya®, 48% for Copaxone®, 45% for Avonex. As regards the variation of adherence in function of time, it shows up that after a year of treatment, the adherence values was stabilized at about 0.9 for Gilenya®, Copaxone® and Avonex, and between 0.8 and 0.85 for Rebif®, Betaferon® and Extavia®. The cost of the daily treatment ranges from a minimum of € 13.66 for Betaferon® to a maximum of 44 € for Gilenya®. The comparison of oral therapy and the injection one showed no significant differences, underlining that in the case of Multiple Sclerosis, oral formulation does not represent a parameter in favour of the adherence to treatment. To equal levels of adherence it is not justifiable the higher cost of fingolimod compared to all other analysed treatments.