TORONTO -- The average Canadian adult does not need to be screened for infection with hepatitis C, a blood-borne virus that can in time cause cirrhosis or cancer of the liver, says a task force that develops practice guidelines for primary-care providers.
In its first hepatitis C screening guidelines released Monday, the Canadian Task Force on Preventive Health Care recommends against widespread testing of adults unless they are considered to have an elevated risk for the disease.
Canadians at high risk include those who: have a history of IV drug use; were born, travelled or resided in countries where hepatitis C is endemic; received blood transfusions or had an organ transplant before 1992, when blood donations weren't tested for the virus; or could have been exposed through potentially hazardous sexual behaviours or by getting a tattoo.
Dr. Roland Grad, chair of the task force working group that developed the guidelines, said two systematic reviews of the medical literature found no evidence of benefit from widespread population screening for hepatitis C among low-risk adults.
"What we are saying is that people who are not at an elevated risk don't need to go for a blood test or be screened for hepatitis C," said Grad, an associate professor of medicine at McGill University with a family practice in Montreal.
"But if you are at elevated risk, you should be tested."
Still, one component of the guidelines is sure to be contentious: the task force recommends against routine hepatitis C screening for baby boomers.
"The reason why we could not recommend screening all baby boomers in Canada is that there is no direct scientific evidence that doing that is going to lead to more benefit than harm," said Grad.
"In fact, there's now some evidence coming out of the United States that screening of baby boomers in the U.S. does not provide better clinical outcomes."
That advice runs counter to what many Canadian doctors have been preaching -- that those born between 1945 and 1965 should be tested for hepatitis C, a recommendation mirrored in 2012 guidelines from the U.S. Centers for Disease Control (CDC) and the U.S. Preventive Services Task Force.
"The burden of disease related to hepatitis C in North America is currently increasing and in fact is larger than the burden of disease posed by all other reportable infectious diseases," including tuberculosis and HIV, said Dr. Julio Montaner, director of the BC Centre of Excellence in HIV/AIDS.
Montaner said there has been a prevailing notion that baby boomers infected with the virus likely contracted it during their teens or early 20s, due to such behaviours as IV drug use or sexual experimentation.
But a study last year by his research team in conjunction with the CDC found that a high proportion were infected as children and the virus was largely spread "iatrogenically" -- meaning it resulted from exposure through inadequately sterilized reusable syringes and needles, for instance, those used in dental freezing and vaccinations.
An estimated 250,000 Canadians are infected with hepatitis C, according to the Canadian Liver Foundation. Many people who become infected never develop symptoms and recover completely. Others get a brief, acute illness with fatigue and jaundice, in which the skin and eyes turn yellow.
However, others can develop chronic hepatitis, which can lead to liver scarring (cirrhosis), liver failure and even liver cancer later in life. Chronic hepatitis C is a "silent" disease because symptoms often don't appear until the liver is severely damaged -- a process that can often take decades.
"We should be offering hepatitis C testing to all high-risk groups -- I agree with that -- but the baby boomers should be offered it too, because in Canada they have twice the rate of infection of the general population," argued Montaner.
"We have a responsibility as a society to say you have an infection that is evolving, you're getting older and therefore the likelihood of this getting worse is significant."
Grad said a key reason why the 12-member working group advises against widespread screening is because of the high cost of testing and treatment, which they estimated at $1.5 billion.
"That's because there are some people in Canada who don't know they have the virus and if we did screen them and treat them, the cost of treatment would be very high, based on the super-high drug costs," he said.
"And in the context of the health-care system, with the large impact that screening and treatment would have on our budget, we had concerns that many individuals that we would identify by screening wouldn't get timely access to specialized treatment."
That treatment includes relatively new drugs known as direct-acting antivirals, or DAAs, which can cure the infection but carry a price tag of $50,000 to $100,000 for an eight- to 24-week course, a cost the task force concluded would be prohibitive for many people.
The guidelines appear in Monday's issue of the Canadian Medical Association Journal, accompanied by a commentary by Drs. Genevieve Cadieux and Herveen Sachdeva of the Dalla Lana School of Public Health in Toronto.
While they acknowledge that widespread testing for a disease is considered unethical if treatment is either unavailable or unaffordable, Cadieux and Sachdeva point out that the pan-Canadian Pharmaceutical Alliance has recently negotiated price reductions for the antiviral drugs.
"Addressing ... system-wide barriers to population-based screening for chronic HCV infection would not only increase capacity within the health system to manage HCV infection in the future, but it would also improve outcomes in patients currently living with chronic HCV infection," they write.
"Population-based screening should be reconsidered in light of price reductions for DAAs, as well as emerging evidence on HCV transmission and long-term health outcomes after treatment.
"Similar to strategies for HIV testing in North America, it is likely that a combination of risk-based testing and population-based screening will be needed in the future."