Disease-modifying drug initiation patterns in commercially insured multiple sclerosis patients: a retrospective cohort study

BACKGROUND The goal of this research was to compare the demographics, clinical characteristics and treatment patterns for newly diagnosed multiple sclerosis (MS) patients in a commercial managed care population who received disease-modifying drug (DMD) therapy versus those not receiving DMD therapy. METHODS A retrospective cohort study using US administrative healthcare claims identified individuals newly diagnosed with MS (no prior MS diagnosis 12 months prior using ICD-9-CM 340) and ≥18 years old during 2001-2007 to characterize them based on demographics, clinical characteristics, and pharmacologic therapy for one year prior to and a minimum of one year post-index. The index date was the first MS diagnosis occurring in the study period. Follow-up of subjects was done by ICD-9-CM code identification and not by actual chart review. Multivariate analyses were conducted to adjust for confounding variables. RESULTS Patients were followed for an average of 35.7±17.5 months after their index diagnosis. Forty-three percent (n=4,462) of incident patients received treatment with at least one of the DMDs during the post-index period. Treated patients were primarily in the younger age categories of 18-44 years of age, with DMD therapy initiated an average of 5.3±9.1 months after the index diagnosis. Once treatment was initiated, 27.7% discontinued DMD therapy after an average of 17.6±14.6 months, and 16.5% had treatment gaps in excess of 60 days. CONCLUSIONS Nearly 60% of newly-diagnosed MS patients in this commercial managed care population remained untreated while over a quarter of treated patients stopped therapy and one-sixth experienced treatment gaps despite the risk of disease progression or a return of pre-treatment disease activity.