Bevacizumab Study Shows Influence of Physician Relationships on Prescribing

A study published Friday in JAMA Network Open found that peer influence factored heavily into whether oncologists decided to eventually adopt bevacizumab for their patients.

The findings indicate that interventions that leverage physician relationships may assist with increasing uptake of new, high-value cancer treatments in place of low-value therapies, the authors said.

The study took place at the time when only the reference product, Avastin, was available. The first biosimilar bevacizumab, Mvasi, became available in the United States in 2017.

Researchers examined adoption of bevacizumab in 2007 to 2010 among oncologists who had not prescribed the drug in 2005 to 2006.

These oncologists who were associated with fellow oncologists who did use bevacizumab in those years had increased use of the drug in 2007 to 2010.

The cohort study took place in 51 randomly selected hospital referral regions in the United States. Participants were 44,012 fee-for-service Medicare beneficiaries aged 65 years or older with cancers of the colorectum, lung, breast, kidney, brain, or ovary treated by 3261 oncologists in 2005 to 2010.

Data were analyzed in 2017 to 2018.

Among patients treated with chemotherapy during 2007 to 2010 by an oncologist who had not treated patients with the biologic in 2005 to 2006, models (adjusted for patient and physician characteristics and physician, practice, and community random effects) assessed the association of bevacizumab use with rates of use among connected physicians in 2005 to 2006. Of the 44,012, 34,750 patients were treated with chemotherapy in 2005 to 2006 in the 51 hospital referral regions.

Among 9262 patients treated in 2007 to 2010 by 829 physicians whose patients did not use bevacizumab in 2005 to 2006, 3654 (39.5%) were aged 75 years or older and 6227 (67.2%) were female.

The rate of bevacizumab use relative to other chemotherapy in 2007 to 2010 by tertile of use among their physician’s peers in 2005 to 2006 was 10.0%, 9.5%, and 13.6%, respectively. For all patients receiving chemotherapy, the receipt of bevacizumab was less than 4.4%, 4.4% to 6.2%, and more than 6.2%, respectively.

After adjustment, use of bevacizumab in 2007 to 2010 was greater among physicians in communities with the highest rates of bevacizumab use in 2005 to 2006 compared with those whose peers were in the lowest tertile of bevacizumab use in 2005 to 2006 (adjusted odds ratio, 1.64; 95% CI, 1.20-2.25).