COST-EFFECTIVENESS OF INTERFERON-ALPHA AND CONVENTIONAL CHEMOTHERAPY IN CHRONIC MYELOGENOUS LEUKEMIA

Objective: To compare the cost-effectiveness of interferon-alpha with that of hydroxyurea as initial therapy for patients with chronic myelo genous leukemia (CML) in the chronic phase. Design: A decision analysi s and Markov model that described the natural history of the therapeut ic process. The Markov model contained two treatment arms (interferon- alpha and hydroxyurea) and eight states of health (complete hematologi c remission with cytogenetic response, complete hematologic remission without cytogenetic response, partial hematologic remission, chronic p hase without hematologic remission, accelerated phase, blast crisis, b one marrow transplantation, and death). Probabilities, costs, and util ities were obtained from published clinical studies and clinical inves tigators. Measurement: Quality-adjusted years of life saved and costs and qualities discounted at 5% per year. Setting: University medical c enters in North America and Europe. Patients: Meta-analysis of results from patients studied in clinical trials. Results: The model's predic tions of median survival (69 months with interferon-alpha therapy and 58 months with hydroxyurea therapy) were derived from data in the rece nt literature. In patients 50 years of age, interferon-alpha improved life expectancy over hydroxyurea by approximately 18 months. The margi nal cost-effectiveness of interferon-alpha (incremental discounted cos t of interferon-alpha compared with that of conventional therapy) was $34 800 per quality-adjusted year of life saved. The model was sensiti ve to the monthly cost of interferon-alpha therapy (if the cost of int erferon-alpha is reduced by one third, the cost-effectiveness becomes $19 300 per quality-adjusted year of life saved) but was not particula rly sensitive to the costs associated with blast crisis or bone marrow transplantation. The other significant variable was quality of life d uring therapy with interferon-alpha; when this measure was varied from 70% to 100% of the quality of life during hydroxyurea therapy, cost-e ffectiveness changed from $123 200 to $25 620 per quality-adjusted yea r of life saved. When the quality of life associated with interferon-a lpha was less than 62% of the quality of life associated with hydroxyu rea, the discounted quality-adjusted life expectancy with interferon-a lpha was less than that with hydroxyurea. Conclusion: Compared with hy droxyurea, interferon-alpha is, in most clinical scenarios, a cost-eff ective initial therapy for patients with chronic-phase CML who can tol erate the drug.