Population based cost utility study of interferon beta-1b in secondary progressive multiple sclerosis

Objective To evaluate the cost utility of interferon beta-1b in secondary p rogressive multiple sclerosis. Design Population based cost utility model (healthcare perspective). Data o n use of health services were obtained from case records and routine morbid ity data and utility values from a EuroQol survey Local and published costs were used. Effectiveness was modelled using data on relative risk reductio ns from a randomised trial of interferon beta-lb. Setting Tayside region, 1993-5. Subjects 132 ambulatory people with secondary; progressive multiple scleros is. Main outcome measures Cost per quality adjusted life lear (QALY) gained. Ra te of relapse and proportion becoming wheelchair dependent ol:er three year s. Results The number needed to treat for 30 months to delay time to wheelchai r dependence in one per-son by nine months was 18 (95% confidence interval 5 to 26), For every 18 people treated for 30 months, sh relapses would be p revented, gaining 0.397 discounted QALYs. The cost per QALY gained was poun d 1 024 667 (pound 276 466 to pound 1 485 499). If treatment was restricted to patients attending neurology services, the number needed to treat was 1 4 (cost per QALY gained pound 833 514 (pound 161 358 to infinity)). The cos t per QALY gained was not sensitive to changes in cost which took account o f a societal perspective. Conclusions The cost per QALY; gained from interferon beta is high because of the high drug cost and modest clinical effect Resources could be used mo re efficiently elsewhere.