A Harvard study shows doctors who take industry payouts are more likely to prescribe brand-name drugs, which is driving up unnecessary healthcare spending.

Some of the most excessive healthcare spending involves the purchase of cholesterol lowering statins. But emerging research suggests there’s a reason for that.

The research, which confirms earlier findings, suggests that if doctors take money from pharmaceutical companies, even just for a free lunch, they’re more likely to prescribe more expensive brand-name drugs.

Researchers from Brigham and Women’s Hospital and Harvard Medical School reviewed the records of about 1.6 million prescriptions for statins covered by Medicare Part D in Massachusetts in 2011.

Of the 2,444 doctors in the Medicare prescribing database, almost 37 percent received industry payments.

Researchers found that physicians who didn’t receive industry money prescribed brand-name statins at a rate of almost 18 percent. Those who did take money prescribed brand-name drugs at a rate of almost 23 percent.

Overall, researchers found that for every $1,000 spent on doctors, brand-name drug prescriptions increased 0.1 percent.

Read More: Prescriptions for Hydrocodone Have Dropped Since DEA Classification »

The most common form of payment was for company-sponsored meals, but payments for educational training translated to an almost 5 percent increase in brand-name prescriptions.

“Our analysis suggests that certain payment types may be more of a cause for concern than others. Of the various forms of payments received by physicians, those for educational training support were associated with higher rates of brand-name prescribing,” the researchers concluded. “Some have argued that such payments are essentially marketing payments and should be disclosed or banned.”

The study authors did note limitations to their study, including accuracy of the reporting of payments and prescriptions covered outside of Medicare.

They also couldn’t determine “which physicians received payments from a specific company and analyze their prescribing of that company’s products.”

They do suggest, however, drug companies may seek out doctors because they already prescribe their drugs. The most commonly prescribed branded statins were Lipitor and Crestor, the study showed.

While not a cause-and-effect smoking gun, the study, published Monday in JAMA Internal Medicine, echoes findings from a ProPublica investigation published in March that connects industry money to an increased likelihood a doctor will prescribe more expense brand-name drugs.

That study examined Medicare prescriptions in 2014, which produced $2.5 billion in government spending. In the fields of cardiology, psychiatry, ophthalmology, family, and internal medicine, between 70 and 90 percent of doctors reported taking payments.

Those who received payments, from meals to speaking fees, were two to three times as likely to have “very high” brand-name prescribing rates than those who didn’t take money.

That study also didn’t prove a cause-and-effect relationship between payments and prescriptions.

Read More: Why Do Statins Work Better in Some People Than Others? »

Generic drugs account for 88 percent of all prescriptions filled in the United States.

Compared to the price of branded drugs, they accounted for an estimated $254 billion in savings in 2014.

Generic drugs for hypertension and cholesterol alone saved the U.S. healthcare system nearly $60 billion that year, according to the Generic Pharmaceutical Association annual report.

Besides providing savings to the most expensive healthcare system in the world, the drugs are less expensive for patients. The average cost of a generic statin is $10 out-of-pocket per month. Branded statins averaged $48.

A 2014 study found, when compared to brand-name statins, Medicare patients taking generics were more likely to adhere to their treatment and had fewer adverse health outcomes as a result. It should be noted that Teva Pharmaceuticals, which manufactures generic statins, funded that study.

Drug companies are increasingly releasing “me-too” drugs once originals go off patent. While the generics are equally effective, these newer, updated formulations can remain under patent and help retain company profits.

“Many physicians prescribe these medications at great cost to the patient and healthcare system even when there is little to no difference from generic alternatives,” Drs. Joshua M. Sharfstein and Jeremy Greene, both of Johns Hopkins University, wrote in a JAMA editorial.

Their editorial also noted that while doctors once viewed generic medications with heavy skepticism, only 1 in 10 doctors now believes generics are inferior to branded drugs.

A different study released Monday in JAMA Internal Medicine states brand-name medications accounted for an extra $73 billion in spending between 2010 and 2012.

During that time, total out-of-pocket expenses for patients were $175 billion, of which 14 percent — nearly $25 billion — were due to brand-name drug overuse, according to the study performed by researchers at The Ohio State University and the University of Michigan.

“There was a large amount of excess expenditure on branded drugs between 2010 and 2012 in classes that could have incorporated therapeutic substitution,” the study concludes. “Although therapeutic substitution is controversial, it offers a potential mechanism to decrease drug costs if it can be implemented in a way that does not negatively affect quality of care.”

Read More: 70 Percent of Americans Take Prescription Drugs »

Patients who are curious about whether their doctors are accepting money from drug companies can search Dollars for Docs, an online database that tracks payments made to doctors.

The project, assembled by ProPublica, is a searchable database of related payments made between August 2013 and December 2014. Those payments do not include research grants and ownership interests.

Pharmaceutical and medical device companies are required by law to disclose payments made to doctors and medical institutions for things like meals, travel expenses, and speaking fees.

The studies each noted that a doctor doesn’t necessarily prescribe a drug because they’ve received money from a drug company. Considering up to 90 percent of doctors in some fields report taking money, it’s also part of the way American medicine does business.