Neutropenia-related costs in patients treated with first-line chemotherapy for advanced non-small cell lung cancer

Neutropenia is a major adverse event often associated with chemotherapy administration. Neutropenia-related complications often lead to increased use of costly health care including inpatient and outpatient services. Monitoring and treatment of neutropenia thus place an economic burden on the health care system.

To evaluate (a) costs and medical resource use for chemotherapy- related afebrile and febrile neutropenia in an elderly population with Stage IIIB or Stage IV non-small cell lung cancer (NSCLC), and (b) costs unrelated to neutropenia and total all-cause health care costs during first-line chemotherapy.

Study patients in this retrospective database analysis were aged 65 years or older with a diagnosis of Stage IIIB or Stage IV NSCLC in the Surveillance, Epidemiology and End Results (SEER) cancer registry from 1998 through 2002. Neutropenia was identified by the presence of a primary or secondary diagnosis code for diseases of white blood cells (ICD-9-CM = 288.xx) during a period of first-line chemotherapy treatment. Febrile neutropenia was defined by (a) an inpatient hospitalization with a primary or secondary diagnosis for neutropenia occurring at any time during first-line chemotherapy or (b) intravenous or intramuscular antibiotic administration occurring after the initial neutropenia diagnosis and during first-line chemotherapy. Patients with neutropenia without these events were considered to have afebrile neutropenia. Patients were followed in the SEER-Medicare database to evaluate costs (defined as all Medicare payments, primary insurer payments, and patient copayments and deductibles) and resource use associated with afebrile or febrile neutropenia while on first-line chemotherapy. If a patient switched to second-line chemotherapy, the day prior to the switch was defined as the end of first-line treatment. If a switch to second-line therapy did not occur, then first-line therapy was assumed to end 30 days following administration of the last first-line agent. Costs were summed for 2 main types of cost measures: neutropenia-related costs, defined as costs for claims with either a primary or secondary diagnosis of neutropenia, and costs unrelated to neutropenia. Costs were classified using ICD-9-CM diagnosis and procedure codes appearing on the claims, with confidence intervals [CIs] for cost measures estimated by using nonparametric bootstrapping methods. Group comparisons of patient characteristics, medical utilization, and cost study measures were made using 2-sided Pearson chi-square and t-test statistics for categorical and continuous measures, respectively. The no neutropenia group was used as the reference category for comparisons involving patient characteristic, medical utilization, and total all-cause health care cost study measures. For total neutropenia-related costs, afebrile and febrile neutropenia study groups were compared.

Among elderly patients treated first-line for advanced NSCLC, 5,138 met inclusion criteria, of whom 1,228 (23.9%) developed afebrile (n = 740, 14.4%) or febrile neutropenia (n = 488, 9.5%) while on first-line chemotherapy. Mean per patient costs for treating neutropenia during first-line chemotherapy were $12,148 (standard deviation [SD] = $15,432, 95% confidence interval [CI] = $10,915-$13,607) for patients with febrile neutropenia and $3,099 (SD = $4,541, 95% CI = $2,796-$3,431) for patients with afebrile neutropenia (P<0.001), with mean (SD) length of follow-up (duration of first-line chemotherapy) of 4.5 (4.8) and 5.5 (7.0) months, respectively. Expressed as a percentage of total all-cause health care costs during first-line chemotherapy, neutropenia-related costs accounted for 32.2% of total costs for patients with febrile neutropenia (mean [SD] = $37,694 [$26,078]) and 9.1% of total costs for patients with afebrile neutropenia (mean [SD] = $34,204 [$26,317]). Mean neutropenia-related costs per patient per month (PPPM) during first-line chemotherapy were $2,700 for patients with febrile neutropenia and $563 for patients with afebrile neutropenia. PPPM costs unrelated to neutropenia for patients with afebrile neutropenia, febrile neutropenia, and no neutropenia, respectively, were $5,655, $5,677, and $6,146. In sensitivity analyses, results were highly sensitive to the definition of neutropenia (i.e., claims with primary diagnosis only vs. primary or secondary diagnosis) but insensitive to the type of chemotherapy regimen.

Neutropenia is a major adverse event that places patients at an increased risk of infection and subsequent morbidity and mortality. For elderly patients undergoing first-line chemotherapy for NSCLC, neutropenia, particularly febrile neutropenia, is associated with substantially higher total all-cause health care costs.