Financial relationships between physicians and the pharmaceutical industry are common.
This article evaluates the magnitude of the association between compensation and prescribing.
Financial relationships between physicians and the pharmaceutical industry are common,
but factors that may determine whether such relationships result in physician practice
changes are unknown. We evaluated physician use of orally administered cancer drugs
for four cancers: prostate (abiraterone, enzalutamide), renal cell (axitinib, everolimus,
pazopanib, sorafenib, sunitinib), lung (afatinib, erlotinib), and chronic myeloid
leukemia (CML; dasatinib, imatinib, nilotinib). Separate physician cohorts were defined
for each cancer type by prescribing history. The primary exposure was the number of
calendar years during 2013–2015 in which a physician received payments from the manufacturer
of one of the studied drugs; the outcome was relative prescribing of that drug in
2015, compared with the other drugs for that cancer. We evaluated whether practice
setting at a National Cancer Institute (NCI)‐designated Comprehensive Cancer Center,
receipt of payments for purposes other than education or research (compensation payments),
maximum annual dollar value received, and institutional conflict‐of‐interest policies
were associated with the strength of the payment‐prescribing association. We used
modified Poisson regression to control confounding by other physician characteristics.
Physicians who received payments for a drug in all 3 years had increased prescribing
of that drug (compared with 0 years), for renal cell (relative risk [RR] 1.81, 95%
confidence interval [CI] 1.58–2.07), CML (RR 1.22, 95% CI 1.08–1.39), and lung (RR
1.69, 95% CI 1.58–1.82), but not prostate (RR 0.97, 95% CI 0.93–1.02). Physicians
who received compensation payments or >$100 annually had increased prescribing compared
with those who did not, but NCI setting and institutional conflict‐of‐interest policies
were not consistently associated with the direction of prescribing change. The association
between industry payments and cancer drug prescribing was greatest among physicians
who received payments consistently (within each calendar year). Receipt of payments
for compensation purposes, such as for consulting or travel, and higher dollar value
of payments were also associated with increased prescribing. Financial payments from
pharmaceutical companies are common among oncologists. It is known from prior work
that oncologists tend to prescribe more of the drugs made by companies that have given
them money. By combining records of industry gifts with prescribing records, this
study identifies the consistency of payments over time, the dollar value of payments,
and payments for compensation as factors that may strengthen the association between
receiving payments and increased prescribing of that company's drug.