Do Oral Disease Modifying Agents (DMTs) Improve Adherence to MS Treatment? a Comparison of Oral and Injectable Drugs

Background: Lack of adherence to treatment, particularly with injectable medications, has been a significant problem in multiple sclerosis and estimated to occur in 20-50% of patients with consequent increase in relapse rate and disease progression. In recent years, therapeutic options for MS have expanded to include three oral options. The impact of oral DMTs in improving adherence to MS treatment is not well known.

Objectives: To determine if adherence and tolerability of oral DMTs is better than with injectables in our MS Center population.

Methods: We developed the MS Treatment Adherence Questionnaire (MS-TAQ) and collected data from October-November 2014. The MS-TAQ is composed of 6 questions: patient’s current DMT, number of missed doses in 4 weeks, reason dose was missed, perceived side effects, ease of administration, and medication satisfaction. Medication types were divided into 3 groups: subcutaneous or intramuscular (SC/IM), monthly IV injections, and oral DMTs. We analyzed the responses using Fisher’s Exact Test (α=0.05) to determine if responses varied by medication type.

Results: We had 209 patients, 75.1% female and 24.9% male, mean age of 50.4 years. Eighty-nine patients (42.5%) were on oral medication, 90 (43%) on a SC/IM drug, and the remaining 30 (14.5%) on an IV infusion. Fifty-five percent of patients on oral DMTs reported no missed doses as compared with 70.8% of patients taking SC/IM and 93.3% on patients receiving IV infusions (p=0.005). Reason for missed dose differed with respect to medication type (p=0.017) with forgetfulness being reported in 37.6% and 26.5% of patients receiving oral and IM/SC DMTs respectively. In addition, side effects were significantly different for each medication type (p<0.0001). The overwhelming majority of those on IV did not experience side effects (74.3%), whereas only a minority of those taking orals (18.6%) and SC/IM (20.2%) responded as such. Ease of taking medication was reported by 77%, 60% and 33% of patients on oral, IV and SC/IM injections, respectively (p<0.0001). Patient satisfaction did not significantly vary by medication type (p=0.235).

Conclusions: In our population, lack of adherence was significantly higher in patients receiving oral as compared to injectable DMTs, despite their reported ease of administration. Side effect profile may have been a contributing factor to this outcome. Health care providers should implement strategies to improve DMT adherence, regardless of medication route.