Hypertension is one of the most preventable and treatable causes of premature death worldwide. Measuring blood pressure regularly, at home, is also one of the best ways to keep track of it. However, according to a new study, most people don’t measure it correctly. Researchers analyzed data from over 11,000 middle-aged adults and found that lying down (not standing) is closely correlated with a higher likelihood of heart disease, stroke, and even death.

There’s a surprising controversy regarding the best way to take people’s blood pressure. The controversy started a couple of years ago when studies suggested that people lying down may have higher blood pressure than when sitting down. It wasn’t the first time something like this was suggested, but studies reported conflicting findings. Some studies reported that people had higher blood pressure while sitting down. Others found that sitting blood pressure was higher.

To get to the root of things, researchers from Harvard tracked participants in the Atherosclerosis Risk in Communities (ARIC) initiative, for over 27 years, assessing the correlation between both sitting and lying blood pressure readings and cardiovascular problems. More than 13,000 adults were initially recruited, but researchers excluded individuals with conditions like coronary heart disease, heart failure, or stroke, ending up with 11,369 participants.

The key finding? Lying down (supine) hypertension was significantly associated with worse cardiovascular outcomes, even in participants who showed normal seated blood pressure.

Your blood pressure when lying down matters more

The study, which was led by Duc M. Giao, produced striking results. Among participants, 16.4% of those without seated hypertension exhibited supine hypertension. Meanwhile, 73.5% of those with seated hypertension also had supine hypertension. For individuals with supine hypertension alone, the risk of cardiovascular events mirrored those with hypertension in both positions. Compared to seated hypertension alone, supine hypertension posed greater risks for:

• Coronary heart disease (60% higher risk);
• Heart failure (83% higher risk);
• Stroke (86% higher risk);
• Fatal coronary heart disease (over twice the risk);
• All-cause mortality (43% higher risk).

The results are considered generalizable (participants were mostly White and Black), and the ARIC staff underwent rigorous training to ensure the validity of the measurements. Researchers had extensive health information on the participants to ensure other elements aren’t skewing the data. In the study, high blood pressure readings were defined for systolic readings (the higher number) of 130 mm Hg or greater or diastolic readings (the lower number) of 80 mm Hg or greater.

The conclusion was that it’s more useful to take blood pressure readings while lying down.

What does this mean?

It’s not clear why supine tension is different than sitting, nor why it would be a better indicator of blood pressure. But this is not the first time researchers have found alternative ways of measuring blood pressure.

Nocturnal hypertension, where blood pressure rises during sleep, has already been linked to cardiovascular risk. Supine hypertension likely reflects similar dynamics, offering a window into how blood pressure behaves outside routine clinic visits.

While the study makes a strong case for considering supine hypertension, it also opens the door to further questions. Could targeted treatments for supine hypertension improve outcomes? How does this condition interact with nocturnal hypertension? Future research could explore these avenues and refine approaches to managing blood pressure across different contexts.

For now, the message is clear: supine hypertension deserves attention. It may offer an important piece of the puzzle in preventing cardiovascular disease and saving lives.

The study “Supine Blood Pressure and Risk of Cardiovascular Disease and Mortality” was published in the journal JAMA Cardiology. doi:10.1001/jamacardio.2024.5213