Economic evaluation of treating clinically isolated syndrome and subsequent multiple sclerosis with interferon beta-1b.

New therapeutic options have modified the natural history and health care costs of multiple sclerosis (MS). An epidemiological 25 years-long model-based cost-utility analysis was performed following the Italian National Health Service (INHS) and societal perspectives to compare costs and quality-adjusted life years of treatment with Interferon beta-1b (IFNB-1b) from diagnosis of clinically isolated syndrome (CIS) versus treating at subsequent conversion to clinically definite MS (CDMS). Among patients treated (untreated) with IFNB-1b from CIS diagnosis, 40,420 (43,700) converted to CDMS after 25 years; the estimated cumulative probability of converting to CDMS during the first 3 years was 72.90% (84.94%) (P < 0.0001). Early treatment with IFNB-1b is highly cost-effective for the INHS (incremental cost-effectiveness ratio: Euros 2,574.94) and dominant from the societal viewpoint. Sensitivity analyses confirmed the base case findings. Early treatment with IFNB-1b delays conversion to CDMS in CIS patients and might be a "good value for money" health care programme.