This is true in high income countries, like Canada, as well as middle and low income countries, say an international team of researchers led by the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences.
The report, which was published today by JAMA
, the journal of the American Medical Association, is part of the PURE (Prospective Urban Rural Epidemiological) study.
"Our study indicates over half of 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 of Sydney University and the George Institute for Global Health in Australia.
Dr. Salim Yusuf, senior author and professor of medicine of McMaster University's Michael G. DeGroote School of Medicine, added that drug treatments that work to control hypertension are well known, however this study found only about a 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.
Participants in the PURE study included 154,000 adults between 35 and 70 years old, 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% of those with hypertension were aware of the diagnosis, while blood pressure was controlled among 32.5% 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 the executive director of the PHRI which initiated the PURE study, the only multi-country study 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, similar organizations in several countries and by unrestricted grants from several pharmaceutical companies.