In pushing for price transparency in health care, advocates have argued that patients can make smarter decisions if they know the cost.

A study in the Journal of Consumer Research suggests, however, that patients might actually make worse choices if they had more price information.

According to Kaiser Health News, one group of patients was told a flu shot cost $25 while a separate group was given a $125 price. In both cases, insurance would pay, so the patients would have no out-of-pocket cost.

Patients in the group offered the lower price thought the vaccine had “high communal need” and was therefore more important to their health. Conversely, the higher price made those in the other group think the vaccine was less accessible and therefore less important. The patients used price information to draw a surprising and inaccurate conclusion.

Researchers said the result could be bad medical decisions, maybe even dangerous ones, according to Kaiser. “Price and risk should be very independent from one another when you think about consumers making informed health care choices,” said Janet Schwartz, a professor at Tulane University and co-author of the study.

It’s a confounding notion that we consumers might really be that foolish in our thinking process. Fortunately, the solution is one that needs to be in place anyway: information both about price and about medical need and effectiveness.

The problem today is that price information is almost totally absent in the decision process, but that doesn’t mean it should be the only factor. There’s no substitute for education and discussion with a health professional to weigh the relative value against the price.