Private clinics selling screenings could be harming Canadians and adding burdens to the public health system, according to a report released on Thursday.

The report, called What's in a Scan, by the Canadian Center for Policy Alternatives looks at how well consumers are informed about the risks and benefits of tests such as CT and PET scans, including misconceptions about how the technologies are regulated.

The study only looked at the use of medical imaging technologies and tests for screening purposes — looking for suspicious signs in people who aren't showing any symptoms — not diagnosing.

"I'm not against screening, but people need to understand that there's serious downsides, and they need to know what those downsides could be before they agree to pay their money," said Alan Cassels, the lead investigator of the study and a health policy researcher at the University of Victoria.

For the study, researchers interviewed more than 20 medical, regulatory and commercial experts on screening, analyzed media reporting and marketing of screening tests, and conducted a nationwide telephone poll of 400 people in November 2008.

The poll suggested that half of those surveyed said a CT scan of the abdomen would deliver the same or less radiation than a conventional chest X-ray, when in fact the radiation is the equivalent of having 400 chest X-rays, Cassels said.

Cancer scares

He first became interested in the topic in 2005, when media reports publicized former prime minister Brian Mulroney's lung CT scan. The scan revealed nodules, for which Mulroney was hospitalized, but he ending up developing potentially fatal complications including sepsis and pancreatitis.

Screening healthy people not only exposes them to radiation, but can also create a flood of false positive findings or cancer scares that lead to unnecessary medical tests that clog the public health care system, the researchers said.

The authors concluded that medical imaging procedures are being marketed and sold to Canadians as effective in screening healthy people for early detection of diseases, even though the screening is expensive, costing between $100 and $2,500, potentially harmful, and not supported by scientific literature or recommended by professional bodies and regulators.

Advertising for the services also generally misinforms consumers about the safety and reliability of screening tests.

To help fill in the gap for high-quality information about new medical imaging tests, the authors included a two-page "Consumer Guide to Screening."

The authors also recommended that the federal government immediately act on the 2004 Auditor General's report on medical devices, and include more resources for the program to ensure the safety of Canadians.

The research paper was funded by Industry Canada. The poll was commissioned through Malatest and Associates.