Impact of increasing adherence to disease-modifying therapies on healthcare resource utilization and direct medical and indirect work loss costs for patients with multiple sclerosis

To estimate the effect of adherence to disease-modifying therapies (DMTs) among patients with multiple sclerosis (MS) on healthcare resource utilization (HRU) and costs, and model the impact of a 10 percentage point increase in adherence on these outcomes. Employed patients, 18-64 years old, with ≥2 MS diagnoses and ≥1 DMT claim during January 1, 2002 to September 30, 2012 were identified from a large commercially-insured US claims database. Adherence was measured as proportion of days covered (PDC) during follow-up. Multivariate regression analyses were conducted to estimate the effect of adherence on HRU related to urgent care (i.e., inpatient or emergency room visit), days of work loss, direct medical cost, and indirect work loss costs. Model coefficients were used to evaluate the impact of a 10 percentage point increase in adherence on the outcomes. A total of 1510 patients were included (mean age = 43.4 years, 64% female). Patients with higher adherence had lower HRU, fewer days of work loss, and lower direct and indirect costs. A 10 percentage point increase in adherence significantly decreased the likelihood of an inpatient or emergency room visit by 9-19%, days of work loss by 3-8%, and direct and indirect costs by 3-5%, depending on the follow-up period (all p