Conflict of interest in economic analyses of aromatase inhibitors in breast cancer: a systematic review.

To determine whether authors conducting economic analyses of aromatase inhibitors in breast cancer are less likely to reach unfavorable conclusions if the economic study is sponsored by the manufacturer of the drug. Articles reporting the economic analyses of aromatase inhibitors in breast cancer were selected from PubMed in May 2009. Information was collected on the types of analysis, the qualitative conclusion, the quantitative results, and the funding sources. Fisher's exact test was conducted to compare the frequency of unfavorable conclusions based on study sponsorship. Thirty-two eligible articles were identified. Twenty-six were funded by pharmaceutical companies, and 4 were funded by non-pharmaceutical companies. Two studies did not report a funding source. Twenty-one studies evaluated aromatase inhibitors in the adjuvant setting, while 11 studies examined their use in advanced breast cancer. Twenty-two studies evaluated one type aromatase inhibitor, while 10 compared multiple types of aromatase inhibitors. Only one of the 26 (4%) pharmaceutical company-sponsored studies reported unfavorable cost-effectiveness of an aromatase inhibitor, which was a competitor's product, whereas two of four (50%) non-pharmaceutical company-sponsored studies concluded aromatase inhibitors are not cost-effective in certain clinical scenarios (P < 0.05). Seven pharmaceutical company-sponsored studies conducted a comparison among several aromatase inhibitors; all 7 studies reported favorable conclusions for the sponsoring company's products. The majority of economic analyses of aromatase inhibitors in breast cancer are sponsored by pharmaceuticals. Economic evaluations of aromatase inhibitors in breast cancer that are funded by a pharmaceutical company are less likely to reach unfavorable conclusions about the sponsor's product.