title: Off-label use of rituximab in a multipayer insurance system.
abstract: OBJECTIVE
  Off-label prescribing in oncology is common and unregulated. The aim of this study was to describe the off-label use of rituximab, a novel anti-CD20 antibody, among patients from a large proprietary insurance database to understand how frequently and appropriately off-label prescribing occurs for this medication.
  
  
  METHODS
  In this descriptive study, 11,232,642 patients were enrolled in the D2 Hawkeye commercial insurance database between 2001 and 2007, and 2,782 patients received rituximab. The main outcome measures were quantity and type of off-label usage, and expenditures for off-label usage.
  
  
  RESULTS
  Seven hundred five (25.3%) patients received rituximab for off-label indications, and of those, 332 (47.1%) received rituximab for uncertain or inadequate evidence-based diagnoses. Expenditures for off-label indications were 17.1% of expenditures for rituximab usage.
  
  
  CONCLUSIONS
  The frequent use of rituximab for off-label indications should lead to improved postapproval surveillance of biologics by the US Food and Drug Administration, so that use can be adequately studied. This will also facilitate improved regulatory mechanisms to ensure evidence-based use.
authors: Department of Biology and Department of Economics, University of California, San Diego; Verisk Health, Waltham, MA; Department of Medicine, Department of Hematology/Oncology, and PRIME Residency Program, San Francisco Veterans Affairs Medical Center, San Francisco, CA; Department of Medicine, and Department of Malignant Hematology and Bone Marrow Transplant, University of California, San Francisco.
authors: Eliezer M
authors: EM
authors: Van Allen
authors: Todd
authors: T
authors: Miyake
authors: Nathan
authors: N
authors: Gunn
authors: Caroline M
authors: CM
authors: Behler
authors: Jeff
authors: J
authors: Kohlwes