BACKGROUND Financial conflicts of interest can influence biomedical research. Using data from the American Society of Hematology and the American Society of Clinical Oncology annual meetings, we evaluated the frequency and influence of financial conflicts of interest on economic analyses in oncology. METHODS We systematically searched for economic analyses among American Society of Hematology (2006 to 2008) and American Society of Clinical Oncology (2004 to 2008) annual meeting abstracts. Information was collected on the presence and type of conflict of interest, type of economic analysis, health technology assessed, and author affiliations. To evaluate the influence of conflicts of interest on study results, the abstracts were categorized into 3 groups based on whether the study conclusions directly supported, indirectly supported, or did not support the sponsor's product. RESULTS Some financial conflicts of interest were present in 236 of 356 (66%) abstracts of economic analyses, which were submitted for presentation at these meetings. Among economic analyses with a conflict of interest, the conclusions of 138 (59%) studies directly supported the sponsor's product. Another 74 (31%) studies with a conflict of interest indirectly supported the sponsor's product. CONCLUSIONS Financial conflicts of interest are prevalent in economic analyses presented at major oncology meetings. The majority of studies with any financial conflict of interest directly or indirectly support the sponsor's product.
