More than one-third of Canadians have not obtained needed health care because of insufficient insurance coverage, according to the results of an online survey released Tuesday.

The poll, conducted in April by Canadian public opinion research company Ipsos Reid for the Canadian Medical Association, found that 36 percent of respondents said they have gone without necessary health care either because they couldn't afford it or didn't have health coverage.

Most affected were those without supplementary health benefits, east-coast residents of Atlantic Canada, low-income earners, women, and those who are self-employed, work part-time or unemployed.

Under the country's publicly funded universal health insurance system, known as medicare, Canadian residents do not pay for necessary medical services, whether it's provided in a doctor's office or in a hospital in the province or territory where they live.

Other health-care expenses, such as prescription drugs, eyeglasses, dental checkups and physiotherapy, are often covered by supplementary health benefit packages.

The poll indicates that coverage is most common among those who are employed and those with annual household incomes of at least 60,000 Canadian dollars (about 60,000 U.S. dollars).

Canada's medicare system is outdated, said John Haggie, president of the Canadian Medical Association, the country's national voluntary organization of physicians.

"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," said Haggie.

Half of respondents said they would support a government-created public program for supplementary health benefits funded by increased taxes, according to the survey.

It also found that two-thirds of respondents were concerned that government-funded health services will be cut back over the next few years.

Meanwhile, 51 percent of 500 employers surveyed in a separate online poll conducted in May said they were concerned about the cost of providing supplementary health benefits for their employees over the next five years.