One student in every Canadian classroom, on average, has high blood pressure or is on the brink of developing it, according to a landmark national report.
The study, released Wednesday by Statistics Canada, is considered the most comprehensive and accurate measures of blood pressure levels in Canadian youth ever conducted.
It found that just under 1 per cent of Canadians aged 6 to 19 have high blood pressure, while 2.1 per cent are on the borderline of developing the condition. By comparison, estimates suggest about 20 per cent of Canadian adults have high blood pressure.
Elevated blood pressure levels among youth were most pronounced in the overweight or obese. Researchers said high blood pressure rates were significantly higher among overweight or obese girls aged 6 to 11 and boys aged 12 to 19.
"It's concerning when you see any type of risk factor developing at a young age," said Ian Janssen, co-author of the study and an assistant professor at the Centre for Obesity Research and Education at Queen's University in Kingston. "When you tend to have high blood pressure as a child, that tends to follow you as you become an adult."
He added that the findings fill a major data gap and help paint a picture of the presence of risk factors for cardiovascular disease and other health problems in young people.
But the report is also significant because it provides a comparison tool that health officials will be able to use in future studies to measure blood pressure trends in Canada's young population.
"This is a big advance," said Norm Campbell, a medical professor at the University of Calgary and Canadian chair in hypertension prevention and control. "This is really a baseline and really probably one of the best indicators of population blood pressure in this age group."
High blood pressure, or hypertension, is a leading risk factor for the development of cardiovascular disease, stroke and other serious health conditions. The risk of high blood pressure is higher among certain groups, such as black people or South Asians, as well as diabetics, the obese and those with a family history of hypertension. High blood pressure rates also increase as people age, with reports suggesting more than 90 per cent of Canadians who live to 80 will develop it unless they take certain mitigating steps, such as exercise and sodium control.
Sodium intake is one of the most easily controlled factors that contribute to high blood pressure. But the Canadian population, including children, consumes double the recommended daily amount for adults.
The information included in the new study was collected by measuring blood pressure levels in 2,079 young people as part of the Canadian Health Measures Survey conducted by Statistics Canada. Unlike many previous blood pressure studies, however, researchers used an automated system to measure blood pressure. It's an important distinction because it means the individuals were alone in a room, lying down when their blood pressure was taken. That helps eliminate the chance blood pressure levels will be artificially inflated as a result of the patient's anxiousness or nervousness, often referred to as the "white-coat syndrome."
Dr. Janssen said experts believe many blood pressure studies may inadvertently exaggerate blood pressure levels to a small degree because of white-coat syndrome. That exaggeration was likely present in previous studies of blood pressure studies of Canadian youth, which is what makes this new study unique.
While the study found the majority of young Canadians don't have high blood pressure, which is considered an extreme indicator of serious health risks, Dr. Janssen says many are still vulnerable to heart disease and other problems because of poor diet and lack of exercise.