Where you live in Ontario could have a lot to do with your risk of having a heart attack or stroke, a massive new study has found.
The peer-reviewed research, published on Monday in the Canadian Medical Association Journal, hammered home the stark divide in health outcomes throughout the province. It found people in northern Ontario faced nearly double the levels of cardiovascular health issues compared to residents in and around Toronto, and one clinician is calling the results a "wake-up call."
Researchers tracked 5.5 million middle-aged adults from 2008 to 2012, looking for heart attacks, strokes and deaths from cardiovascular issues. None of the adults — all between 40 and 79 — had a history of cardiovascular disease.
"What we found were rather striking two-fold differences in the incidence of cardiovascular disease between Ontarians living in different parts of the province," said lead author Dr. Jack Tu, a senior scientist at the Toronto-based Institute for Clinical Evaluative Sciences.
Tu, who's also a cardiologist at Sunnybrook's Schulich Heart Centre and was an expert adviser for CBC's Rate My Hospital project, has long studied regional variations in cardiovascular deaths.
His latest "big data" study with the Cardiovascular Health in Ambulatory Care Research Team included data from various health-care databases maintained by Ontario government, and broke information down by Local Health Integration Networks (LHINs).
The research found the healthiest three LHINs were all in the Greater Toronto Area, with the Mississauga Halton LHIN, Toronto Central LHIN and Central LHIN coming out on top.
Those three had the fewest cardiovascular health issues during the study period, with 3.2 to 3.5 events out of every 1,000 person-years — a statistical measurement used to express incidence rates.
The four least-healthy LHINs were the North East LHIN and North West LHIN — both in northern Ontario — along with the North Simcoe Muskoka LHIN and Erie St. Clair LHIN.
Those areas were found to have the most cardiovascular health issues, with 4.8 to 5.7 events out of every 1,000 person-years — or roughly double those of the most healthy LHINs.
"Those living in the areas with the lowest burden of disease were the most likely to have received cardiovascular preventative services — such as having an annual physical, seeing their doctor to have their cholesterol and diabetes checked, and having their blood pressure controlled," noted Tu.
In contrast, people in the least-healthy areas were less likely to receive preventive screening tests or have an annual physician, and also visited a family doctor less often. They were also more likely to be obese or smoke, and have the lowest intake of fruits and vegetables.
The researchers determined improving access to preventive health-care services could boost cardiovascular health.
Tu said his team account for the many other factors that contributed to each person's health, such as their ethnic background or whether they were immigrants.
By using a statistical analysis method to make predictions, the researchers determined that factors within Ontario's health system, such as access to preventive health care, account for roughly 15 per cent of the difference in health levels between different regions.
"The data suggests that there's a significant number of Ontarians who are not being fully assessed for cardiovascular risk in the middle-age range," Tu said.
Toronto emergency room physician Dr. Brett Belchetz agreed, and praised the research for its "incredible size" and the length of the followup time.
"The disparity here is obviously far greater than I ever would've expected. The outcomes are far worse for rural areas than I ever would've expected. I think it's a wake-up call for all of us in the province that we have a bigger problem on our hands than we realized," said Belchetz, who was not involved in the research.
Belchetz said it has long been known that access to care is trickier in rural communities, thanks to reduced access to lab testing and a lower physician-to-patient ratio. Increased access to doctors, screening, and better education are all key to reducing the health divide, he said.
"The fact that we're seeing rates of these types of illnesses that are almost double in rural areas than they are in cities — that's something that's unacceptable," he added.
Tu acknowledged there were limitations to the research, which was funded primarily by an operating grant from the Institute of Circulatory and Respiratory Health-Canadian Institutes of Health Research.
There was a lack of complete data for every health indicator used for the millions of people in the study, for instance, and the team also couldn't be 100 per cent sure of a causal relationship between various risk factors and someone having a cardiovascular issue.
But he still stressed the importance of patients taking their health care into their own hands by getting fully assessed and screened — wherever they live — and said policymakers need to consider geography when they're determining health-care policies.