Physician Characteristics and Variability of Erythropoiesis-Stimulating Agent Use Among Medicare Patients With Cancer

Purpose Drugs are usually approved for a specific indication on the basis of randomized trials. However, once approved, these treatments are often used differently than as tested in trials. We performed an analysis to determine the patterns of use of erythropoiesis-stimulating agents (ESAs). Methods We used the Surveillance, Epidemiology, and End Results–Medicare database to identify patients age 65 years or older with breast, lung, or colon cancer diagnosed between 1995 and 2005 who had one ESA and chemotherapy claim. Associations of patient, tumor, and physician-related factors with receipt of ESAs were analyzed. Results Of 21,091 patients analyzed, 5,099 (24.2%) received ESAs for 1 week or less (misuse), and 1,601 (7.6%) received ESAs for more than 14 weeks (prolonged use). Receipt of ESAs while not actively receiving chemotherapy (off label) occurred in 2,876 patients (13.6%). In a multivariable analysis, ESA misuse was associated with MD degree, female sex of physician, and earlier year of medical sc...