The Impact of Emerging Safety and Effectiveness Evidence on the Use of Physician-administered Drugs: The Case of Bevacizumab for Breast Cancer

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Abstract

Background:

Spending on physician-administered drugs is high and uses not approved by the US Food and Drug Administration (FDA) are frequent. Although these drugs may be targets of future policy efforts to rationalize use, little is known regarding how physicians respond to emerging safety and effectiveness evidence.

Study objective:

We analyzed changes in bevacizumab (Avastin) use for breast cancer in response to its market launch (February 2008), 2 FDA meetings reviewing data suggesting that its risks exceed its benefits (July 2010 and June 2011), and the FDA’s withdrawal of approval (November 2011).

Data:

Data from a population-based audit of oncologists’ prescribing (IntrinsiQ Intellidose) were used to measure the monthly number of breast cancer patients treated with bevacizumab (January 2008–April 2012).

Methods:

The number of bevacizumab patients following each regulatory action was estimated using negative binomial regression, compared with patients before the first FDA meeting, adjusting for cancer stage, treatment line, patient age, and outpatient office affiliation.

Results:

Bevacizumab use for breast cancer increased significantly after FDA approval. After all regulatory actions, there was a 65% decline (95% CI, 64%–65%) in use compared with the period before the first meeting. The largest decline was in the 6-month period after the first meeting (37%; 95% CI, 28%–47%). The rate of decline did not differ by patient or cancer characteristics and differed minimally by office affiliation.

Discussion:

Bevacizumab use for breast cancer declined dramatically after FDA meetings and regulatory actions, a period without changes in guideline recommendations or insurance coverage. Physicians seem to be responsive to emerging evidence concerning physician-administered drug safety and effectiveness.

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