Cost-Effectiveness of Imatinib Versus Interferon-α in the Treatment of Patients Newly Diagnosed with Chronic Myeloid Leukemia, under the Brazilian Public Healthcare System Perspective.

The 60-month follow-up data for patients randomized to imatinib in IRIS demonstrated significant clinical improvements in survival rates and QALYs gained (17,09 years;13,58 QALYs) in patients newly diagnosed with chronic myeloid leukemia (CML) and treated with imatinib in comparison to patients under interferon-alpha (INF-α) (9,10 years;6,31 QALYS) as first line therapy. Although reimbursed as second line therapy for chronic phase CML patients who did not respond to INF-α, imatinib was not considered for public reimbursement as first line treatment in Brazil based solely on drug costs. An economic evaluation of imatinib as first line treatment versus INF-α was performed under the Brazilian Public Heathcare System perspective, according to the long-term follow-up data from IRIS, literature recommendations and prior health technology assessment from the National Institute for Clinical Excellence (NICE) to consider long term follow-up survival and adverse events costs.

This study was aimed to evaluate the cost-effectiveness of imatinib compared with IFN-α for first-line treatment of chronic myeloid leukemia under the Brazilian public healthcare system perspective.

For the economic model, a base case of 100 patients for each treatment option was constructed focused on drug costs and adverse events. Drug costs were estimated based on the Brazilian public healthcare reimbursement payment (APAC-SUS) for chronic phase CML treatment. Febrile neutropenia (grade III and IV), depression, nausea and abnormal liver-function results were considered as adverse events. Clinical guidelines and protocols from two public hematology Brazilian centers, Fundação Pró-Sangue FM-USP and Instituto Nacional do Cancer, were used to estimate adverse events treatment costs. Adverse events frequency for all grades was based on data published by NICE and the Agency for Health Care Research and Quality. Due to the high crossover rate from INF-α to Imatinib group observed in the IRIS study (90% from INF-α to imatinib within a year of study entry) the estimated life time survival for INF-α treatment group was based on the European Study Group on Interferon in Chronic Myeloid Leukemia. Utilities values from the IRIS study were used for both groups. Annual discount rates were of 6% for costs and 1.5% for QALYs.

The annual average costs for the treatment of adverse effects in the INF-α were 1.83 higher than the imatinib group. Adverse events lifetime costs for INF-α were 24% higher than imatinib, even tough imatinib granted a projected 6.3 years survival advantage over INF-α.

The resulting incremental cost-effectiveness ratio (ICER) of imatinib, compared with IFNα, considering adverse events was US$ 18,637 per QALY gained. Assuming a conservative cost-effectiveness threshold of less than US$ 25,500, which is three times the GDP per capita in Brazil (US$ 8,500 in 2005), the ICER for imatinib compared with INF-α falls within the range considered by the World Heath Organization as a cost-effective fist line treatment for patients newly diagnosed with CML.