A study led by the Population Health Research Institute and a team of international researchers has found that many patients don’t know they have hypertension, and even if they do, too few are receiving adequate drug therapy.

According to the findings, this is true in high-income countries such as Canada, as well as middle and low-income countries.

The report, which was published Tuesday by JAMA (Journal of the American Medical Association) is part of the larger PURE (Prospective Urban Rural Epidemiological) study.

Dr. Salim Yusuf, senior author and professor of medicine at McMaster’s Michael G. DeGroote School of Medicine, explained that drug treatments designed to control hypertension are well known. However, the study found that only one third of patients who are aware of their condition were achieving target blood pressure control.

“Blood pressure lowering drugs are generally inexpensive and commonly available treatments,” said Yusuf. “However only a third of patients commenced on treatment are on enough treatment to control their blood pressure. This is worst in low-income countries, but significant in high and middle income countries too.”

This is important because hypertension, or high blood pressure, is the leading cause of cardiovascular disease, which is associated with at least 7.6 million deaths per year worldwide.

“Our study indicates that over half of the people with hypertension are unaware of their condition and, amongst those identified, very few are taking enough treatment to control their blood pressure,” said Dr. Clara Chow, lead author, a member of PHRI and an associate professor of medicine at Sydney University and the George Institute for Global Health in Australia.

Participants in the PURE study included 154,000 adults between the ages of 35 and 70, with and without a history of heart disease or stroke, from 17 high, middle and low-income countries.

Each participant had their blood pressure measured and medication use recorded, along with information about their age, gender, education and key risk factors, including whether they knew they had hypertension. The study found 46.5 per cent of those with hypertension were aware of the diagnosis, while blood pressure was controlled among 32.5 per cent of those being treated.

The authors could only guess at potential solutions for the poor detection and inadequate treatment of hypertension.

“The findings are disturbing and indicate a need for systematic efforts to better detect those with high blood pressure,” said Yusuf. “Early use of combination therapies, that is, two or more types of blood pressure-lowering treatments taken together, may be required.”

Yusuf is executive director of PHRI, which initiated the unique multi-country study (the only one of its kind). The study was funded by more than 25 organizations including the Canadian Institutes for Health Research, the Heart and Stroke Foundation of Ontario and by unrestricted grants from several pharmaceutical companies.