Regular visits from community health workers to monitor high blood pressure can dramatically reduce cardiovascular mortality and disability in low- to middle-income countries, a new study suggests.

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Measuring blood pressure at home could slash cardiovascular mortality rates in certain countries.

As a significant risk factor for cardiovascular and kidney diseases, uncontrolled high blood pressure or hypertension is a leading cause of death globally.

But because a person with hypertension has no obvious symptoms, many doctors and healthcare professionals call it a silent killer.

Many adults living in rural areas of low- and middle-income countries have hypertension, about 70% of which is uncontrolled by medication.

As a result, cardiovascular mortality is increasing in these countries, according to an article in the New England Journal of Medicine. The risk is particularly high in areas where there is significant poverty, and healthcare systems are fragmented.

There is ample evidence that controlling hypertension reduces deaths from cardiovascular disease.

The challenge in lower-income countries is to develop affordable strategies to encourage people with hypertension to take drugs for reducing blood pressure and lowering cholesterol.

In South Asia, China, Mexico, and Africa, community health workers carry out home visits to deliver maternity and child care.

So, researchers wondered whether adopting a similar door-to-door healthcare service for people with hypertension would improve control of high blood pressure.

To find out, they recruited 2,465 adults with hypertension living in 30 rural villages in Bangladesh, Pakistan, and Sri Lanka.

These 30 communities were randomly assigned to continue usual care or to receive a visit every 3 months by trained community health workers.

The health workers measured blood pressure using digital monitors and gave people advice about lifestyle and the importance of taking medication.

The health workers referred people with poorly controlled blood pressure and those at high risk of cardiovascular disease to specially trained doctors at local primary care clinics.

A blood pressure reading has two numbers — for example, 140/90 millimeters of mercury (mm Hg). The first number is the systolic pressure, which refers to the pressure in arteries as the heart muscle contracts. The second relates to the diastolic pressure, which measures blood pressure between heartbeats.

Two years after the study started, the intervention group saw a 5mm Hg greater reduction in mean systolic blood pressure than in the control group.

Reduction in mean diastolic blood pressure was also higher among people in the intervention group, and more people managed to get their blood pressure under control. Experts define this as a reading of less than 140/90 mm Hg.

The results of the study, called COBRA-BPS (Control of Blood Pressure and Risk Attenuation — Bangladesh, Pakistan, Sri Lanka), appear in The New England Journal of Medicine.

Professor Tazeen H. Jafar of Duke-NUS Medical School in Singapore, who led the study, says other research has shown that a sustained 5 mm Hg reduction in systolic BP across a community can lead to a 30% reduction in death and disability from cardiovascular disease.

A full cost-effectiveness analysis is underway, but early results suggest that if rolled out across all three countries, the program would cost less than $11 per person per year.

Prof. Jafar, who is also a professor of global health at the Duke Global Health Institute in the U.S., comments on the findings.

“Our study demonstrates that an intervention led by community health workers and delivered using the existing healthcare systems in Bangladesh, Pakistan, and Sri Lanka can lead to clinically meaningful reductions in BP as well as confer additional benefits — all at a low cost.”

– Prof. Tazeen H. Jafar

Dr. Imtiaz Jehan of Aga Khan University in Karachi, who was the study’s principal investigator in Pakistan, says uncontrolled hypertension and lack of awareness of the disease are “alarmingly high” in her country.

“Controlling BP through lifestyle modification and antihypertensive therapy can be the single most important way to prevent the rising rates of cardiovascular disease and deaths in Pakistan,” she says.

The study found that being visited at home by community health workers and referrals to specially trained doctors made people more likely to take antihypertensive and lipid-lowering medications.

Despite people with hypertension having access to the drugs free of charge through state healthcare in Sri Lanka, only about 25% successfully control their blood pressure, says principal investigator in Sri Lanka Prof. H. Asita de Silva of Kelaniya University.

“Traditional approaches to health service delivery, reliant on people presenting to clinics, are clearly not good enough,” he adds.

“Instead, innovative models of cardiovascular care must incorporate primary healthcare strategies that enhance reach to underserved populations.”

Prof. Jafar believes the public health implications of the new findings in developing countries are far-reaching.

“A low-cost program like ours could be adapted and scaled up in many other settings globally, using the existing healthcare infrastructure to reduce the growing burden of uncontrolled hypertension and potentially save millions of lives, as well as reduce suffering from heart attacks, strokes, heart failure, and kidney disease.”

–Professor Tazeen H. Jafar