US patients who receive free drug samples have significantly higher out-of-pocket prescription costs than those who do not, new research has found.

Patients who never received drug samples had $178 estimated out-of-pocket prescription costs over six months, while those receiving samples spent an estimated $166 for a six-month period prior to getting the free drugs, $244 for the six months in which they received the samples and $212 for the subsequent six months, says the study, which was published in the March 24 issue of the journal Medical Care.

These findings suggest that physicians “should use caution in assuming that the use of free samples ultimately reduces patients’ out-of-pocket prescription cost,” said study author Caleb Alexander, assistant professor of medicine at the University of Chicago Medical Center.

Using the Agency for Healthcare Research and Quality (AHRQ)’s Medical Expenditure Panel Survey, Dr Alexander’s team followed 5,709 patients for up to two years. The patients’ average age was 48 years, 84% of them were white, 76% had private insurance and 14% received at least one drug sample, with a total of 2,343 samples dispensed during the analysis period.

The study found that the odds of receiving samples were lower for older patients and also for those who had Medicaid (the US federal health care programme for people on low incomes) as their source of insurance coverage. One reason for this could be that those who received samples may have been more seriously ill than those who did not, but this would explain only a part of the difference in out-of-pocket costs, say the authors.

An equally important factor, they believe, is that patients who receive free samples may end up paying for a prescription for the medicine which they have initially received for free, and they note that medicines given as free samples are often the newest and the most expensive.

“Samples may be particularly valuable in providing patients economic relief when they are used short-term and not followed-up with long-term prescription for the same medicine. However, all too often, physicians and patients end up continuing the medicines initially begun as samples, even though older, less expensive alternatives may exist,” said Dr Alexander. “Regardless of the degree to which these different mechanisms account for our findings, patients and physicians should consider complementary ways to reduce patients’ burden from out-of-pocket prescription costs, such as using more generic medicines, stopping non-essential treatments and using three-month rather than one-month supplies,” he added.