Canada prides itself on its universal health care system and many Canadians don't understand why the United States allows millions of Americans to go without health insurance coverage.
But an Ipsos-Reid poll commissioned by the three health bodies suggests many Canadians don't have adequate medical coverage despite universal medicare.
The gap, according to the association, is in supplementary health benefits.
The Canadian Medical Association (CMA), one of the survey's sponsors, said in a news release that more than one-third of those polled say either they or a family member has foregone needed health care because of insufficient insurance coverage.
The gap is highest among those polled in Atlantic Canada, lower-income earners, women and self-employed, part-time or unemployed Canadians, the poll found.
China's Xinhua news agency noted in its report on the poll that under universal medicare administered by the provinces and territories, Canadians don't pay for necessary medical services either from their doctor or at a hospital.
But other expenses, such as prescription drugs, glasses, dental checkups and physiotherapy, are often covered by supplementary health benefit packages, which are usually provided by an individual's employer.
The poll found supplementary coverage is most common among those who are employed and those with annual household incomes of at least $60,000, Xinhua said.
"With close to one fifth of Canadians — that's six million people — lacking supplementary health care coverage, this is clearly a gap that needs to be addressed," Maureen O'Neil, CEO of the Canadian Health Services Research Foundation, a poll co-sponsor, said in the news release.
"When people can't afford the health care they need, there are economic costs both through reduced productivity and greater health care expenditures down the road."
The online survey of 2,020 people, conducted April 23-30, found 82 per cent of respondents had supplementary health care coverage while 18 per cent did not, the Northumberland View reported.
Those without supplementary coverage said they were paying more out-of-pocket for various health services. The amount they spent was comparable to those with benefits, suggesting those without coverage were simply foregoing treatment.
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CMA president Dr. John Haggie said in the news release that it's time to update Canada's approach.
"Our medicare system that covers only physician and hospital care was designed when these were the most important forms of treating patients," said Haggie.
"Public health coverage has not kept up with medical advancements that see more and more Canadians being treated through advanced surgical treatments and new pharmaceuticals."
Half the poll respondents said they would support a public supplementary health benefits program funded by increased taxes.
A separate survey of 500 employers, conducted May 7-14, found three-quarters of respondents were worried that cash-strapped governments would reduce coverage of insured health services. They were split on whether there should be a taxpayer-funded program for supplementary benefits.
The polls had margins of error of 2.2 per cent 19 times out of 20.