(Zoran Ivanovich/iStock)

Nicole Van Groningen is an internal medicine physician at the University of California at San Francisco.

The last time you left your doctor’s office with a new prescription, you probably assumed she thoughtfully selected it as the best treatment for your condition. But if your doctor — like half of American physicians — accepts visits and the occasional free lunch from pharmaceutical representatives, there’s a good chance that drug choice was heavily biased.

Physicians — myself included — aren’t immune to the behavioral manipulation of marketers, and Big Pharma knows it. In 2012, the pharmaceutical industry spent $24 billion marketing its premium branded drugs to health-care professionals — eight times the amount it spent on advertising to consumers. In recent years, a growing segment of the medical community has spoken out against the industry’s inordinate efforts to influence doctors. Since 2006, a number of teaching hospitals have enacted policies that restrict or ban visits from pharmaceutical representatives in hopes of limiting the industry’s influence. And last month, the California Senate passed a bill that would ban drug companies from giving gifts to doctors.

The bill coincides with the release of hard evidence that spending money to influence doctors actually works. A study published last month in JAMA found that physicians from hospitals that restricted visits and gifts from drug representatives ordered significantly fewer promoted brand-name medications and prescribed more cost-effective generic versions than those in other hospitals.

The study isn’t the first to highlight the disconcerting link between doctors’ prescribing habits and their interactions with pharmaceutical representatives. A 2016 ProPublica analysis found that physicians who received payments from drug and medical device companies were significantly more likely to prescribe high-cost branded medications. In another study, researchers found that a single drug-company-sponsored meal can make a physician more likely to prescribe an expensive brand-name cholesterol medication instead of a less expensive generic one.

My own experience with the pharmaceutical industry bears witness to this unsettling phenomenon. Once, as a junior medical resident, a pharmaceutical representative visited my department and offered to take a handful of us to a trendy Manhattan restaurant as part of an “educational” dinner. I went. The drug that was promoted that evening, which cost roughly 500 percent more than a dirt-cheap (and just as effective) alternative, still sticks out in my mind as a go-to treatment option for a common disease in my field. I’m sure this isn’t a coincidence.

The losers in this pharmaceutical industry-physician interaction are, of course, patients. The high costs of branded drugs are revenue to drug companies, but out-of-pocket expenses to health-care consumers. Almost a quarter of Americans who take prescription drugs report that they have difficulty affording their medications, and the high costs of these drugs is a leading reason that patients can’t adhere to them. Most branded drugs offer minimal — if any — benefit over generic formulations. And if doctors prescribe brand-name drugs that are prohibitively more expensive than generic options, patients might forgo the medications altogether — causing greater harm.

On a national scale, the financial burden imposed by branded drugs is enormous. Current estimates place our prescription drug spending at more than $400 billion annually, and branded drugs are almost entirely to blame: Though they constitute only 10 percent of prescriptions, they account for 72 percent of total drug spending. Even modest reductions in our use of branded prescription drugs — on par with the roughly 8 percent relative reduction seen in the JAMA study — could translate to billions of dollars in national health-care savings.

Pharmaceutical companies maintain that their visits to doctors serve an educational purpose in that they allow drug reps to communicate important details about new medications to would-be prescribers. But with the widespread availability of high-quality sources for ongoing medical education, it’s hard to imagine a gap in physicians’ knowledge base that would be best filled by a visiting drug representative.

And as any doctor can tell you, truly valuable drugs sell themselves. Adoptions of new antiviral medications for hepatitis C, for instance, went through the roof — even with their hefty price tags — in the wake of clinical trials that showed the extraordinary benefit of the new medications over the old standard of care. The case for these drugs was made with high-quality clinical evidence, not with marketing.

Admittedly, the problem of rising prescription drug prices has deep and complicated roots that extend beyond the drug industry’s direct influence on physicians. But restricting pharmaceutical representatives’ access to our clinics and hospitals is a low-effort and high-yield first step in bending the cost curve.