MODELING THE COST-EFFECTIVENESS OF GRANULOCYTE-COLONY-STIMULATING FACTOR USE IN EARLY-STAGE BREAST-CANCER

Purpose: To model the cost-effectiveness (CE) of granulocyte colony-st imulating factor (G-CSF) in early-stage breast cancer when its use is directed to those most in need of the medication. Methods: a condition al CE model was developed for the use of G-CSF based on a ranking of p atient need as determined by patient blood counts during the first cyc le of chemotherapy. In the base case, no G-CSF was used. In the altern ative case, C-CSF was used in the following manner. If the risk Of a n eutropenic even) las defined by a predictive model based on nadir abso lute neutrophil count [ANC] and hemoglobin decrease in cycle 1) was eq ual to or exceeded a predetermined critical value ''T,'' then patients would receive G-CSF in cycles 2 through 6 of chemotherapy. If the ris k of an event was less than T, patients would not use G-CSF unless an event occurred, at which time G-CSF would be administered with every s ubsequent cycle. Results: A decision rule (T) that would allow the mos t needy 50% of early-stage breast cancer patients to receive G-CSF aft er the first cycle of chemotherapy resulted in a CE ratio of $34,297 d ollars per life-year served (LYS). If only the most needy 10% of patie nts received G-CSF, then the associated CE ratio was $23,748/LYS; if 9 0% of patients could receive the medication, the CE ratio would be $76 ,487/LYS. These estimates were relatively insensitive to inpatient hos pital cost estimates (inpatient costs for fever and neutropenia of $3, 090 to $7,726 per admission produced dollar per LYS figures of $34,297 to $32,415, respectively). However, the model was sensitive to assump tions about the shape of the relationship between dose reduction and d isease-free survival (DFS) at 3 years. Conclusion: Providing G-CSF to the neediest 50% of early-stage breast cancer patients las defined by first-cycle blood counts) starting after the first cycle of chemothera py is associated with a CE ratio of $34,297/LYS, which is well in the range of CE ratios for treatment of other common medical conditions. F urthermore, conditional CE studies, based on predictive models that in corporate individual patient risk, allow one to define populations for which therapy is, or is not, cost-effective. Limitations of our prese nt understanding of the shape of the chemotherapy dose-response curve, especially at low levels of dose reductions, affect these results. Fu rther work is required to define the shape of the dose-response curve in early-stage breast cancer. (C) 1998 by American Society of Clinical Oncology.