Cost-effectiveness of interferon in chronic myeloid leukaemia: analysis of four clinical studies

Analysis of published survival curves can be used as the basis for incremental cost-effectiveness analyses in which two treatments are compared with one another in terms of cost per life-year saved. In patients with chronic myeloid leukaemia in chronic phase, long-term treatment with alpha-interferon has been reported to improve survival in comparison with standard treatments with cytotoxic drugs. To assess the pharmacoeconomic profile of interferon treatment in terms of cost per life-year gained, we conducted an incremental cost-effectiveness analysis.

The clinical material utilised in our analysis derived from four published randomised trials comparing interferon vs. busulphan or hydroxyurea. The Gompertz model was used to estimate the total lifetime values of patient-years of subjects receiving interferon in comparison with subjects given a standard cytotoxic treatment.

Our primary analysis showed that maintenance treatment with interferon improved survival expectancy by 37 to 93 discounted years for every 100 patients. The incremental cost-effectiveness ratio of interferon vs. cytotoxic therapy ranged from $93,000 to $226,000 per life-year gained (discounted costs per discounted years). A secondary analysis showed that the dose of interferon had significant influence on the cost-effectiveness ratio. Because our literature search identified a fifth study that showed an extremely favourable outcome using interferon but that was not included in our primary analysis due to its design, we conducted another secondary analysis based on these five studies that, however, confirmed the results of the primary analysis.

Our study indicates that an unselected long-term treatment with interferon implies an unfavourable cost effectiveness ranking in comparison with data of cost per life-year gained which had previously been obtained from other types of medical intervention.