Here it comes again -- an idea that surfaces regularly in Canadian health care debates and seems to hold sway with those who advocate common sense principles: user fees.

Some people think that charging patients when they use the health system would help control health care costs, ensure that people are getting the care they need and are not overusing the system. Others believe that user fees would bring in much-needed revenue.

Unfortunately the evidence doesn't support the aspirations. Research to date suggests two good reasons why patient-financed healthcare doesn't make sense.

First, user fees discourage patients from seeking both necessary and unnecessary care. This is often penny wise and pound foolish.

Some claim that user fees are benign because they discourage only frivolous use. That assumes that most people have the expert knowledge to know what care is needed. A host of studies have found the opposite. One U.S. study published in the New England Journal of Medicine involving fairly healthy adults showed that user fees led to a 20 per cent increase in risk of death for people with high blood pressure because people were less likely to see a doctor and get their blood pressure under control.

The same thing happened in Canada in 1996, when Quebec began requiring patients to pay part of the cost of all drugs purchased. As a result, according to a study in the Journal of the American Medical Association, patients reduced their use of less essential drugs and essential drugs, with negative effects on their health including serious adverse events and increased emergency department visits.

Faced with user fees, the evidence shows that people often do without preventative care and chronic disease management. User fees mean we have to decide whether or not symptoms warrant medical attention. For example, when a child has a fever, most parents don't know whether it's the flu or the onset of meningitis. Do we really want parents to make the decision about whether to take their child to the doctor on the basis of whether the user fee will leave enough money to pay the rent?

Which leads to the second finding.

Health care financed by patients does not save money. It may transfer costs from third-party payers to patients, but the total cost is often higher. Indeed, this helps explain the contradictory beliefs noted above -- if user fees bring in new revenue, they cannot simultaneously control costs.

One reason relates to what happens to resources not used by those discouraged from seeking care. While user fees sometimes discourage sick people from filling hospital beds or booking doctors appointments, research shows that these freed up resources are not closed down. Instead, they often end up providing people who can more easily afford the user fees care they may not need. That is, user fees may -- ironically -- encourage unnecessary or marginally useful care in order to make sure the physicians and hospital beds available stay busy.

Individual patients also have less ability to negotiate prices, particularly when they are very ill. In other words, it may cost more to buy the same.

Let's face it: most people don't want a heart transplant or a hip replaced just because they're free. Doctors, not patients, determine who gets access to most healthcare treatments. So what do user fees really discourage? They discourage the frugal and the poor from getting the care they really need.

When the patient pays, buying insurance is typically part of the package -- unfortunately, that package can change rapidly. A recent report from the U.S. based Commonwealth Fund describes sharp rises in premiums for employer-sponsored family plans over the period 2003 to 2009 with premiums increasing more than three times faster than median incomes. Deductibles have also risen nearly 80 per cent over this period. And it is precisely the sickest -- who need the most care -- who have the greatest trouble in finding an insurance company willing to cover them.

One type of user fee that might make sense was recently proposed in Europe: add user fees to low-value services and eliminate them from high value services. But that takes a lot of work up front to figure out what medical care works and what doesn't and for whom, and to convince patients and providers that these decisions are accurate. No one has yet tried this approach.

The scientific evidence supporting publicly financed care is long and strong. So why do discredited ideas like user fees keep coming back?

Dr. Bob Evans and his colleagues have examined this issue and refer to user fees and related ideas as "zombies." That's because they have been killed off repeatedly by the scientific evidence, but, just like zombies, they keep bouncing back to life to wreak havoc with our public policy.

Noralou Roos is Professor of the Faculty of Medicine at the University of Manitoba and the co-founder of EvidenceNetwork.ca, a comprehensive and non-partisan online resource designed to help journalists covering health policy issues in Canada. Raisa Deber is a Professor of Health Policy, Management and Evaluation at the Faculty of Medicine, University of Toronto, and an Expert Advisor with EvidenceNetwork.ca