In a retrospective analysis using claims data from a commercially insured population (2010-2019), we assigned patients to treatment arms based on DMTs received during the coverage period: no DMT (ND), high-efficacy (HE) (alemtuzumab, B-cell depletion, cladribine, natalizumab), and standard-efficacy (SE) DMT (dimethyl fumarate, glatiramer acetate, interferon-beta, sphingosine-1-phosphate receptor modulator, teriflunomide). We obtained healthcare expenditure (USD) and occurrences of healthcare services: outpatient visits, emergency room (ER) visits, hospitalizations, brain and spine magnetic resonance imaging (MRI). We quantified relapses (based on MS-related hospitalizations, as well as outpatient visits with prescription of high-dose steroids) and medical complexity (based on unique drug classes of prescriptions). We calculated the incidence rate ratio across groups using negative binomial regression, with ND as reference, adjusting for relevant covariates.  We calculated mean cumulative healthcare costs using a generalized linear model with log-link function and gamma distribution, adjusting for covariates.

Among the 25,932 patients (mean age=53 years, 75% women) with ≥3 months preceding and ≥12 months of insurance coverage after MS classification, both HE and SE groups had significantly more overall outpatient doctor visits, neurology visits, MS-related brain, and spine MRIs as well as relapses and medical complexities than ND, while there was no difference in hospitalizations for MS.  Relative to ND, both HE and SE groups had higher pharmacy costs and overall healthcare costs 12-months after treatment initiation, despite having lower or equivalent non-pharmacy medical costs. Pharmacy costs accounted for ~65% of overall healthcare costs with >85% of pharmacy costs attributable to DMT costs in DMT-treated patients.

DMT cost is a key driver of the healthcare expenditure in MS, highlighting the need for prospective comparative studies towards value-based medicine.