Doctors who received more than $5,000 from companies in 2014 typically had the highest brand-name prescribing percentages. 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.

ProPublica’s analysis doesn’t prove industry payments sway doctors to prescribe particular drugs, or even a particular company’s drugs. Rather, it shows that payments are associated with an approach to prescribing that, writ large, benefits drug companies’ bottom line.

“It again confirms the prevailing wisdom … that there is a relationship between payments and brand-name prescribing,” said Aaron Kesselheim, an associate professor of medicine at Harvard Medical School who provided guidance on early versions of ProPublica’s analysis. “This feeds into the ongoing conversation about the propriety of these sorts of relationships. Hopefully we’re getting past the point where people will say, ‘Oh, there’s no evidence that these relationships change physicians’ prescribing practices.’”

Numerous studies show that generics, which must meet rigid Food and Drug Administration standards, work as well as name brands for most patients. Brand-name drugs typically cost more than generics and are more heavily advertised. Although some medications do not have exact generic versions, there usually is a similar one in the same category. In addition, when it comes to patient satisfaction, there isn’t much difference between brands and generics, according to data collected by the website Iodine, which is building a repository of user reviews on drugs.

There’s wide variation from state to state when it comes to the proportion of prescribers who take industry money, our analysis found. The rate in Nevada, Alabama, Kentucky, and South Carolina was twice as high as in Vermont, Minnesota, Wisconsin, and Maine.

But overall, payments are widespread. Nationwide, nearly nine in 10 cardiologists who wrote at least 1,000 prescriptions for Medicare patients received payments from a drug or device company in 2014, while seven in 10 internists and family practitioners did.

Walid Gellad, an associate professor of medicine at the University of Pittsburgh and co-director of its Center for Pharmaceutical Policy and Prescribing, who also reviewed our analysis, said the pervasiveness of payments is noteworthy. “You can debate if these payments are good or bad, or neither, but what isn’t debatable is that they permeate the profession.”

The results make sense, said Richard Baron, the president and chief executive of the American Board of Internal Medicine. Doctors nowadays almost have to go out of their way to avoid taking payments from companies, according to Baron. And those who do probably have greater skepticism about the value of brand-name medications. Conversely, doctors have to work to cultivate deep ties with companies—those worth more than $5,000 a year — and such doctors probably have a greater receptiveness to brand-name drugs, he said.