Even when given free medicine, heart attack survivors are unlikely to consistently take the medications prescribed to prevent further disease and save lives, according to a new study led by Harvard Medical School researchers.

Previous research showed that one-third of Americans cited cost as a reason they didn’t fill a prescription or used less medicine than they should. In this study, researchers set out to determine if patients would be more likely to follow their doctors’ orders if their medications were free.

Led by Dr. Niteesh K. Choudhry of Harvard-affiliated Brigham and Women’s Hospital, the study offered 2,845 of 5,855 total participants free drugs including cholesterol-lowering statins and lifesaving medications that regulate heart rate and prevent subsequent complications. The other patients, chosen at random, were responsible for their own copayments for the same drug regimens.

The findings, published online by The New England Journal of Medicine and presented this past Monday at an American Heart Association conference, reveal that the share of patients who filled their prescriptions increased only modestly after a year, from 38.9 percent in the group that paid part of the cost to 44.3 percent among patients given the same drugs for free.

While the incidence of heart attacks, strokes, chest pain, and heart failure was notably lower in the group offered free medicine, the authors said the small gain in adherence signaled a need for further investigation of other factors contributing to the problem.

Choudhry, associate professor at Harvard Medical School, said cost is by no means the only cause of non-adherence. Knowledge of drugs and their side effects, ease of filling prescriptions, the number of pills prescribed, and forgetfulness are also factors. “It is well-known that the more pills you have to take during the course of the day, the less likely you are to be adherent,” he said. “Many of these patients have to take six to 10 pills a day on average — it is important to make it as simple as possible for patients to obtain their medication from the pharmacy so that they will continue to take them.”

Choudhry and his team are taking steps to further investigate and find solutions to the phenomenon of non-adherence. Said Dr. Elliott M. Antman, Harvard Medical School professor and another author of the study, “What we have learned is that a combination of reducing cost barriers and interventions will be necessary to produce any sustained improvement. It will be important to have integrated health care teams that will support the patient, not only face-to-face, but also via email and text messaging. We live in a very digital world, and should utilize it.”

In fact, one strategy proposed by Choudhry is to have patients sign a contract agreeing to take their medicine — and be able to prove that they are — in exchange for a small stipend. Another idea is to regularly remind patients of their medical routines via text messaging. For Choudhry, the results of these efforts will be incremental, but effective in concert. “Reducing each factor will likely only increase adherence by five or 10 percent, but if we can combine them, then we can talk about a sizeable improvement,” he said.

The cost of the drugs used in the study was covered by Aetna, the commercial insurer of all participants. Choudhry said the insurer is considering implementing a similar free medication program in the near future, made economically feasible by reductions in the cost of subsequent hospital care for patients who take the free drugs.

This area of research reflects a shifting attitude toward health care and the job of doctors. “Many doctors think that their job is done after they write a prescription and the patient walks out the door,” said Dr. Robert J. Glynn, associate professor in biostatistics and the statistician of the study. “But that’s just not true — a lot of people just don’t like taking their pills, and we need to start addressing the reasons for that.”