Use of colony-stimulating factors with chemotherapy: opportunities for cost savings and improved outcomes.

Myeloid colony-stimulating factors (CSFs) decrease the risk of febrile neutropenia (FN) from high-risk chemotherapy regimens administered to patients at 20% or greater risk of FN, but little is known about their use in clinical practice. We evaluated CSF use in a multiregional population-based cohort of lung and colorectal cancer patients (N = 1849). Only 17% (95% confidence interval [CI] = 8% to 26%) patients treated with high-risk chemotherapy regimens received CSFs, compared with 18% (95% CI = 16% to 20%) and 10% (95% CI = 8% to 12%) of patients treated with intermediate- (10%-20% risk of FN) and low-risk (<10% risk of FN) chemotherapy regimens, respectively. Using a generalized estimating equation model, we found that enrollment in a health maintenance organization (HMO) was strongly associated with a lower adjusted odds of discretionary CSF use, compared with non-HMO patients (odds ratio = 0.44, 95% CI = 0.32 to 0.60, P < .001). All statistical tests were two-sided. Overall, 96% (95% CI = 93% to 98%) of CSFs were administered in scenarios where CSF therapy is not recommended by evidence-based guidelines. This finding suggests that policies to decrease CSF use in patients at lower or intermediate risk of FN may yield substantial cost savings without compromising patient outcomes.