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Thursday 01 May 2003

Effect of off-label use of oncology drugs on pharmaceutical costs: the rituximab experience.

By: Kocs D, Fendrick AM.

Am J Manag Care 2003 May;9(5):393-400; quiz 401-2

BACKGROUND: While the off-label use of oncology interventions is widespread, the factors influencing off-label use and the resultant influence on oncology drug expenditures are not well understood. STUDY DESIGN: To assess the indications for rituximab use, a retrospective review was undertaken at a single academic center between September 1998 and June 2001. METHODS: Patient diagnoses were linked to pharmacy records, and each administration of rituximab was classified as either on-label or off-label as defined by FDA-approved indications. The resultant utilization patterns were the foundation for a conceptual model designed to identify factors that influence off-label use of oncology-related therapeutics and forecast the effect of off-label use on aggregate oncology drug expenditures. RESULTS: One hundred one patients received a total of 428 rituximab administrations during the study period. Most (320, 75%) of the administrations were for off-label indications. Although the extent of off-label and on-label use grew at a similar rate initially, off-label utilization increased nearly exponentially over time as on-label uses lessened. A conceptual model that describes factors that promote, inhibit, or have a mixed influence on off-label use may help predict future patterns of off-label utilization and allow better forecasting of oncology drug expenditures. CONCLUSIONS: The off-label use of rituximab is substantial. Projections of oncology-related patterns of care and drug expenditures must account for the potential for off-label use.

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