OBJECTIVE: To evaluate the pharmacoeconomics of mitoxantrone (m) therapy in patients with progressive-relapsing and secondary-progressive multiple sclerosis (MS). METHODS: The MIMS trial showed that m improves several outcomes in patients with progressive-relapsing and secondary-progressive multiple sclerosis (MS). Patients receiving m 12 mg/m2 every three months had fewer relapses and hospitalizations, less progression of neurologic disability, and improved quality of life and functionality. A pharmacoeconomic analysis was undertaken to compare resource consumption in the m and placebo (p) groups. Major cost drivers were identified as follows: drug therapy, including acquisition, administration, and monitoring (primarily m, IV corticosteroids, and antibiotics); hospitalizations (5 days/occurrence); physician visits (1/relapse); days lost from work (2/documented relapse, 3 additional for relapse requiring IV corticosteroids, and 7/hospitalization). Standard costs were assigned as follows: m ($1000/cycle); IV corticosteroids used to treat relapses ($1250/occurrence); antibiotics used to treat infections ($300/occurrence); hospitalizations ($1850/day); physician visits ($100/occurrence); wages ($160/day). RESULTS: A cost-minimization analysis was done and the cost per patient per year was found to be as follows: m therapy (m=$4000, p=$0); IV corticosteroid therapy (m=$250, p=$750); antibiotic therapy (m=$96, p=$39); hospitalization (m=$1850, p=$3145); physician visits (m=$40, p=$100); lost wages (m=$448, p=$989). The total annual cost per patient was $6684 in the m group and $5023 in the p group. The annual cost of m ($4000) was substantially offset by a reduction in other costs associated with p for a total annual incremental m cost of $1661. CONCLUSIONS: MS is a chronic, debilitating disease associated with considerable costs. Pharmacoeconomic analyses suggest that m compares favorably with other disease-modifying therapies for MS. Additional data will be presented using remaining direct and indirect cost drivers. The results of cost-effectiveness analyses incorporating patient outcome measures will also be presented.