Updated estimates of survival and cost effectiveness for imatinib versus interferon-alpha plus low-dose cytarabine for newly diagnosed chronic-phase chronic myeloid leukaemia.
BACKGROUND
For trials in which participants are followed beyond the main study period to assess long-term outcomes, economic evaluations conducted using short-term data should be systematically updated to reflect new information.


METHODS
We used 60-month survival data from the IRIS (International Randomized study of Interferon vs STI571) trial to update previously published cost-effectiveness estimates, based on 19 months of follow-up, of imatinib versus interferon (IFN)-alpha plus low-dose cytarabine in patients with chronic-phase chronic myeloid leukaemia. For patients treated with imatinib, we used the 60-month data to calibrate the survival curves generated from the original cost-effectiveness model. We used historical data to model survival for patients randomized to IFNalpha. We updated costs for medical resources using 2006 Medicare reimbursement rates and applied average wholesale prices (AWPs) and wholesale acquisition costs (WACs) to study medications.


RESULTS
Five-year survival for patients randomized to imatinib was better than predicted in the original model (89.4% vs 83.2%). We estimated remaining life expectancy with first-line imatinib to be 19.1 life-years (3.8 life-years over the original model) and 15.2 QALYs (3.1 QALYs over the original estimate). Estimates for IFNalpha remained at 9.1 life-years and 6.3 QALYs. When we applied AWPs to study medications, incremental cost-effectiveness ratios (ICERs) were $US 51,800-57,500 per QALY. When we applied WACs, ICERs were $US 42,000-46,200 per QALY.


CONCLUSIONS
Although the analysis revealed that the original survival estimates were conservative, the updated cost-effectiveness ratios were consistent with, or slightly higher than, the original estimates, depending on the method for assigning costs to study medications.
Reed
Shelby D
SD
Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina 27715, USA. shelby.reed@duke.edu
Anstrom
Kevin J
KJ
Li
Yanhong
Y
Schulman
Kevin A
KA
D000970:Antineoplastic Agents / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000191:economics* / Q000627:therapeutic use*; D001549:Benzamides; D003561:Cytarabine / Q000008:administration & dosage; D006801:Humans; D000068877:Imatinib Mesylate; D007370:Interferon Type I / Q000008:administration & dosage; D015466:Leukemia, Myeloid, Chronic-Phase / Q000188:drug therapy* / Q000191:economics*; D010879:Piperazines / Q000008:administration & dosage; D011743:Pyrimidines / Q000008:administration & dosage; D016032:Randomized Controlled Trials as Topic; D011994:Recombinant Proteins; D016019:Survival Analysis
D000970:Antineoplastic Agents; D001549:Benzamides; D007370:Interferon Type I; D010879:Piperazines; D011743:Pyrimidines; D011994:Recombinant Proteins; D003561:Cytarabine; D000068877:Imatinib Mesylate