A number of factors should influence a doctor’s prescribing practices, from illness treatability to new research on drug effectiveness. There’s another less medically based factor that may weigh just as heavily in a doctor’s prescribing habits: gifts from pharmaceutical sales representatives. While numerous past studies suggest a troubling link between money spent on physicians by pharmaceutical salespeople and the increased likelihood that drug brands they peddle will be prescribed, new research concludes the price may be even cheaper than previously thought. The survey finds that taking a doctor out for a single, relatively cheap meal raises the chances a physician will prescribe the expensive, name-brand drugs a rep is promoting over less costly generics.

UC San Francisco researchers looked at the prescribing patterns of 279,669 Medicare Part D doctors from 2013, and found that among physicians who had been taken out for meals by pharmaceutical salespeople, the prescribing rates of the drugs being promoted increased. In an article about their findings, study authors note “that physicians who received just one meal…were up to two times as likely to prescribe the promoted brand-name drugs as physicians who received no meals.” Doctors who were wined and dined on multiple occasions “were three times as likely to do so.” While researchers stress that further study is needed to determine causation, versus mere correlation, they do point out that there is a “strong association between the two events.”

At the very least, the findings suggest that physicians are, overall, fairly cheap dates—on average, the meals cost less than $20.

“What was most surprising to me was that such small payments were associated with big differences in physician prescriptions,” study co-author Colette DeJong told Bloomberg. “It was previously thought it takes a certain amount of money to influence a doctor, and the current guidelines are written that way.”

The popular perception of pharmaceutical industry payments to doctors is of lavish luxury gifts, from trips and conferences in far-flung locales to exorbitant speaking fees. Study authors point to a ProPublica investigation from earlier this year that found a proportional relationship between the amount of money a doctor receives and the probability and the number of name-brand prescriptions the doctor writes. “Doctors who received more than $5,000 from companies in 2014 typically had the highest brand-name prescribing percentages,” the magazine determined. “Among internists who received no payments, for example, the average brand-name prescribing rate was about 20 percent, compared to about 30 percent for those who received more than $5,000.”

This new study seems to indicate that pharma companies can be more frugal and still see a return on their investment—though it probably helps to have a good sales pitch, too.

“There’s really no way that a $10 bagel sandwich can influence a doctor in a gift way,” DeJong told NPR. “We think it represents more reciprocity, the time spent with the drug rep and the fact that the doctor is listening to this 10-minute pitch.”

The researchers looked at Medicare doctors who wrote scripts in four “common drug classes.” These included medications that lower cholesterol levels, treat hypertension, address cardiovascular issues, and antidepressants. They then determined “the most-prescribed brand-name drug” in each of those areas: Crestor, Benicar, Bystolic and Pristiq, respectively. The next step was to identify physicians who were bought meals by pharmaceutical reps pushing those brand-name drugs. (The numbers are available thanks to the 2010 Physician Payments Sunshine Act, under the Affordable Care Act, which put the kibosh on under-the-table gift giving.) As Bloomberg notes, “doctors who received four or more meals paid by the industry prescribed Crestor at 1.8 times the rate of those who received no free meals. The ratio was 4.5 times for Benicar and 3.4 times for Pristiq.”

The pharmaceutical industry, perhaps unsurprisingly, disagreed with the study findings and issued an email statement clarifying its issue with the numbers. “This study cherry-picks physician prescribing data for a subset of medicines to advance a false narrative,” PhRMA’s message reads. “Manufacturers routinely engage with physicians to share drug safety and efficacy information, new indications for approved medicines and potential side effects of medicines.”

Name-brand drug prices in the U.S. are among the highest in the world, thanks to limited regulation and our weird tendency to leave citizens’ health care to the whims of the free market. For many Americans, generic drugs offer an affordable alternative to pricey branded medications. Among the drug classes researched for the study, researchers point out that the generics in each category are considered on par, in terms of efficacy, with their brand-name equivalents. Insurance companies often offer limited coverage, or no coverage at all, for expensive big-name medications. “The Department of Veterans Affairs does not include any of these brand-name drugs on its formulary,” researchers note.

Considering that the doctors in the study were all Medicare physicians, it’s safe to assume that the majority of their patients are likely people over 65, many of whom are among the most financially vulnerable Americans. A 2015 Kaiser Family Foundation report points out that a significant portion of the elderly “have limited incomes…and have modest savings.” In 2013, the same year the researchers studied, “half of all people on Medicare had incomes less than $23,500, which is equivalent to 200 percent of poverty in 2015.”

“A lot of the financial burden of using brand-name drugs instead of generic drugs falls on the seniors enrolled in Medicare, who pay an average monthly co-pay of $40 to $80 for brand-name drugs, but only $1 for generics,” says DeJong.

Affordability is a key determinant in whether seniors consistently take necessary prescribed drugs, which in turn has an obvious impact on health outcomes and quality of life. The choice between being able to afford crucial medications or, say, food is one no person in the richest country on the planet should ever have to make.

NPR points to an editor’s note by Robert Steinbrook of Yale School of Medicine that calls into question, beyond meals and yet more luxe perks, the very practice of pharma gift-giving overall.

“Outright gifts, such as meals, may be legal, but why should physicians either expect or accept them?” Steinbrook asks. “There are inherent tensions between the profits of healthcare companies, the independence of physicians and the integrity of our work, and the affordability of medical care. If drug and device manufacturers were to stop sending money to physicians for promotional speaking, meals and other activities, without clear medical justifications and invest more in independent bona fide research on safety, effectiveness, and affordability, our patients and the health care system would be better off.”

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