Modeling the cost-effectiveness of a new treatment for MS (natalizumab) compared with current standard practice in Sweden.

OBJECTIVE To estimate the cost-effectiveness of a new treatment (natalizumab) for multiple sclerosis (MS) compared with current standard therapy with disease-modifying drugs (DMDs) in Sweden. METHODS A Markov model was constructed to illustrate disease progression based on functional disability (the Expanded Disability Status Scale (EDSS)). The effectiveness of natalizumab was based on a 2-year clinical trial in 942 patients (AFFIRM). The effectiveness of current DMDs was estimated from a matched sample of 512 patients in the Stockholm MS registry. Patients withdrawing from treatment were assumed to follow the disease course of 824 patients with relapsing-remitting disease at onset in the Ontario natural history cohort. Costs and utilities are based on a recent observational study in 1339 patients. All data sets were available at the patient level. Main results are presented from the societal perspective, over a 20-year time frame, in 2005 Euros (euro1 = 9.25 SEK). RESULTS In the base case, treatment with natalizumab was less expensive and more effective than treatment with current DMDs. When only healthcare costs were considered, the cost per quality-adjusted life year gained with natalizumab was euro38 145. Results are sensitive only to the time horizon of the analysis and assumptions about effectiveness of natalizumab beyond the trial. CONCLUSIONS This cost-effectiveness analysis used registry data, cohort and observational studies to extrapolate the efficacy findings of natalizumab from the AFFIRM clinical trial to measure effectiveness in clinical practice. The analysis results suggest that for the population considered, natalizumab provides an additional health benefit at a similar cost to current DMDs from a societal perspective.