Worldwide, more than half of all patients with hypertension are unaware they have the condition, researchers found.

Among a population of patients from 17 countries with hypertension, only 46.5% were aware of their diagnosis, according to Salim Yusuf, MD, DPhil, of Hamilton General Hospital in Hamilton, Ontario, and colleagues.

The majority of those who were did know they had high blood pressure received drug treatment for hypertension (87.5%), but only about a third of those had their hypertension under control (32.5% of those receiving drug treatment), they wrote online in the Journal of the American Medical Association.

The authors noted that hypertension is the leading cause of cardiovascular disease and death globally, and is associated with 13.5% of all deaths. A number of effective and inexpensive blood pressure-lowering treatments exist, making the condition entirely controllable, and mobidity and mortality associated with it preventable, they added.

The authors performed a cross-sectional global analysis on the prevalence, awareness, treatment, and control of hypertension in a population of 142,042 participants from 17 countries. Data were grouped by country income through the Prospective Urban Rural Epidemiology (PURE) study. High-income countries included Canada, Sweden, and the United Arab Emirates. Upper-middle-income countries included Argentina, Brazil, Chile, Polands, Turkey, Malaysia, and South Africa. Lower-middle-income countries included China, Colombia, and Iran. Low-income-countries included Bangladesh, India, Pakistan, and Bimbabwe. Data from U.S. patients were not included in the study. Participants were followed for 10 years, were 35 to 70 at baseline, and received measurements of cardiovascular disease risk factor history - including smoking, history of hypertension, psychosocial factors, alcohol consumptions, and physical measures - and sitting blood pressure. Hypertension status was defined through self-report and receipt of blood pressure-lowering treatment, or an average systolic blood pressure of 140 mm/Hg and an average diastolic blood pressure of 90 mm/Hg, or if the participant had a systolic and diastolic blood pressure that exceeded previously shown levels. Patients were considered to have stage 2 hypertension if they had a systolic blood pressure of 160 mm/Hg and a diastolic blood pressure of 100 mm/Hg. Primary outcomes were measures of participants awareness of their hypertension status, use of treatment for hypertension, and whether or not hypertension was controlled. Control was defined as bringing hypertensive patients down to average blood pressure measurements below 140 mm Hg systolic and 90 mm Hg diastolic. In the total study population, 40.8% had hypertension and the mean blood pressure was 131/82 mm/Hg. Participants who were 50 and older “consistently had greater awareness of their hypertension compared with younger participants, and had higher rates of treatment and control,” they wrote. Older patients also consistently had a higher prevalence of hypertension versus younger patients (P<0.001 for all). Compared with patients in middle- or higher-income nations, those in low-income countries had the lowest rates of awareness of their hypertension and of treatment (P<0.001 for both). Among those receiving medication for hypertension, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers were the most common drugs taken (13.6%), followed by beta blockers (8.2%), calcium antagonists (8.2%), and diuretics (7%). Roughly one-third (30.8%) had two or more medications on their antihypertensive drug lists. In the U.S., nearly one in three adults have hypertension. A study of U.S. patients in July 2013 showed that hypertension and High cholesterol - two commonly co-occurring conditions - were both adequately controlled in just over 30% of those affected by both. Screening and treatment of hypertension in patients from underdeveloped countries should decrease global morbidity and mortality burdens from the condition, noted Steven Almany, MD, of Beaumont Hospital in Royal Oak, Mich. "We need to screen more people and increase awareness of this problem," Almany told MedPage Today, adding that this matter was still troubling because even those who were being treated for hypertension were only controlling it in one out of every three cases. Although overall rates of hypertension awareness and control were concerning, rates of medication usage were lowest in low-income countries, the authors noted. They concluded that "models of care that shift the detection and initial treatment of hypertension to nonphysician health workers should be considered" to meet this shortfall in treatment abroad. They noted that the study was limited by a lack of generalizability of data from each country to each country, low response rates in low-income countries, and a single measure of hypertension in participants.