People with heart disease spend a lot less on medications when they take steps to lower their risk of complications by doing things like getting enough exercise, avoiding cigarettes and keeping their blood pressure in check, a U.S. study suggests.

For the study, researchers focused on adults diagnosed with the most common type of heart disease, known as atherosclerosis, which happens when fats, cholesterol and other substances build up on artery walls.

When these patients did as much as they could to avoid so-called modifiable risk factors for heart disease - inactivity, obesity, smoking, high cholesterol, elevated blood pressure and diabetes - their total average annual pharmaceutical expenditures were $1,400, the study found.

But patients who did little to modify these risk factors had total average annual pharmaceutical expenditures of $4,516, researchers report in the Journal of the American Heart Association.

"Individuals who are unwilling to modify their lifestyles so as to have a favorable risk factor profile would most likely resort to medications to control the risk factors," said lead study author Dr. Joseph Salami of the Center for Health Care Advancement and Outcomes at Baptist Health South Florida in Coral Gables.

"A person getting little or no exercise has a higher risk of obesity," Salami said by email. "Someone obese is more likely to have diabetes, high blood cholesterol and hypertension."

For the study, researchers examined 2012 and 2013 data from the Medical Expenditure Panel Survey, a national snapshot of spending based on surveys of almost 76,000 American patients, families, doctors and employers. The total pharmaceutical costs, reported in 2013 dollars, include patients' out-of-pocket fees like co-payments and co-insurance as well as the portion of the tab covered by insurance or other sources, Salami said.

Among the survey participants, 4,248 adults aged 40 or older had atherosclerosis, representing about 21.9 million people in the U.S. population. They were 68 years old on average, and 45 percent were women.

Overall, average annual drug costs for each participant were $3,432. About a third of this was for cardiovascular disease drugs and another 14 percent was spent on diabetes medicines.

The remaining expenditures - more than half of the total - were for non-cardiovascular disease and non-diabetes drugs and were significantly associated with the modifiable risk factors, the study team notes.

Nationwide, this adds up to annual drug spending of $71.6 billion for patients with atherosclerosis, researchers estimated.

One limitation of the study is that it might overestimate expenditures because it's possible some people prescribed medications for heart disease might be taking them for other reasons, the authors note. Researchers also lacked data on the type of insurance patients' had or for individual characteristics of patients, doctors or pharmacists that might influence drug costs.

Costs should be considered in the context of how well treatments work, and the study doesn't address this, noted Dr. Aaron Kesselheim, a researcher at Brigham and Women’s Hospital and Harvard Medical School in Boston who wasn't involved in the study.

"In some cases, the benefit that patients get from these non-pharmacologic therapies may be much more substantial than the benefit that drug therapy can offer," Kesselheim said by email. "In other cases, the drug might be more helpful."

The study also isn't a controlled experiment designed to prove that people will spend less on drugs when they make lifestyle changes to reduce their risk of heart disease, said Julie Schmittdiel of the Kaiser Permanente Northern California Division of Research in Oakland.

"It does suggest there is promise that addressing modifiable health behaviors will reduce costs," Schmittdiel, who wasn't involved in the study, said by email.

Knowing this might help motivate some patients to make changes, said Stacie Dusetzina, a pharmacy researcher at the University of North Carolina at Chapel Hill who wasn't involved in the study.

"I think many of us realize how hard these risk factors are to modify," Dusetzina said by email. "But having incentives that include feeling better and saving money may help with motivation."