Drug company promotion negatively affects how doctors prescribe: Insights from a new Cochrane review

When you seek medical care, you hope that your doctor will present you with treatment options that are proven to be effective for your condition, that harms do not outweigh benefits and that recommended treatments are affordable and account for your personal situation.

But if your doctor has been influenced by messages, payments or gifts from drug companies, that is unlikely to be the case, as our team from Australia, Canada, the United Kingdom and the United States found.

Pharmaceutical industry promotion is a global phenomenon. In the mid 2010s, companies in the U.S. spent just under US$30 billion annually to convince doctors to prescribe their products.

Figures in other countries are harder to come by but in the mid 2010s, close to CA$500 million was being spent in Canada on advertising in medical journals and on sales representatives who visit doctors’ offices. Between 2015 to 2024, 17,519 Australian doctors received AU$148.7 million from pharmaceutical companies for conferences, travel costs or consultancy fees.

In 2020, seven of the top 10 largest pharmaceutical companies globally spent more on marketing than on developing new drugs. Our research examines the relationship between pharmaceutical promotion and doctors’ prescribing.

Evidence shows the effects of promotion

Our Cochrane systematic review looked at the results of 93 studies involving millions of doctors and published largely over the past two decades. Due to their rigour, Cochrane reviews are considered the gold standard for evidence synthesis.

We examined what happens to the appropriateness, quantity and cost of prescriptions when doctors accept payments or meals from the pharmaceutical industry or rely on pharmaceutical representatives for their education or prescribing information.

We looked at the effects of a range of types of promotion: advertising and industry-sponsored education, gifts such as free meals and payments for consulting or advisory board membership and free drug samples.

The result is not good news for patients.

Doctors who receive gifts or payments prescribe less appropriately and issue more prescriptions — and those prescriptions tend to be more costly. Exposure to pharmaceutical advertising or education probably increases how many prescriptions a doctor issues and may increase costs and decrease appropriateness. The evidence on the effects of free samples is less clear, as there were fewer studies.

We also looked at whether conflict-of-interest policies make a difference. Some medical schools and hospitals have policies limiting interactions among students, trainees or doctors and the industry, such as banning sales visits or specific types of gifts. The result is more appropriate prescribing and possibly fewer prescriptions. The longer the exposure and the stricter the policies, the greater the effect.

Greater exposure to promotion has greater effects

The more company-sponsored meals that doctors ate and the more gifts or payments they received, the more their prescribing deteriorated. The more expensive the gift or the higher the value of the payment, the worse the outcome on prescribing.

A meal worth as little as US$20 led to more prescriptions for the drug made by the company providing the meal. With each additional meal, doctors issued more prescriptions.

Disturbingly, given the legacy of opioid addiction and deaths from overdose, the more meals from opioid manufacturers doctors received, the more opioids they prescribed.

‘I can’t be bought for the price of a sandwich’

Doctors recognize the commercial motivation behind industry’s interactions with them, but do not believe they are affected. Comments to the effect of “I can’t be bought for the price of a sandwich” are a common refrain. Our results convincingly demonstrate those denials cannot be justified.

Most doctors who interact with drug companies are not being bribed; companies do not require prescriptions in exchange for gifts. Clinicians are affected through the “gift relationship.” Receiving a gift of any kind or size, whether wanted or unwanted, creates an obligation — often unconscious — for individuals to repay what they have received.

Michael Oldani, a former sales representative who is now a medical anthropologist who researches pharmaceutical marketing tactics, describes the central role played by the gift relationship in an ethnographic analysis of the influence of sales representatives on prescribing.

Promotion also provides a reminder that focuses clinicians’ attention on promoted products so they’re more likely to think of these products when making a prescribing decision.

From transparency data to public health action

The extent of our review is possible because of a recent large expansion in research on pharmaceutical promotion due to the implementation of the 2013 Physician Payments Sunshine Act in the U.S., and other similar national transparency databases that record payments from drug companies to doctors.

The Sunshine Act alone includes payments to more than a million doctors. Another database records the several million prescriptions written by these doctors.

Combining these databases offers significantly more data, allowing for the identification of more precise associations between payments and prescribing. That includes showing that the greater the exposure, the greater the effect.

Our findings reinforce why pharmaceutical promotion must be addressed as a commercial determinant of health — a key pathway through which corporations negatively impact public health. Commercial determinants of health have been defined as “the systems, practices, and pathways through which commercial actors drive health and equity.” Commercial determinants play a key role in the obesity epidemic, the rapid global growth in noncommunicable diseases and the climate emergency.

Our review convincingly settles the debate about the effects of promotion on the way that doctors prescribe and shows that promotion is likely to be a major commercial determinant of (ill)-health.

The medical community and governments can no longer ignore the consequences of the promotion of medicines on prescribing. It is time for strong concrete action to be taken to put an end to the way that companies are allowed to influence doctors.

This article was also co-authored by Geoffrey Spurling, Associate Professor at the University of Queensland, Riaz Qureshi, Assistant Professor at the University of Colorado Anschutz Medical Campus, and Lisa Bero, Professor of Medicine and Public Health at the Center for Bioethics and Humanities, University of Colorado Anschutz Medical Campus.