Should Clinic BP Be Routinely Measured Lying Down?

Megan Brooks

September 14, 2023

Taking a patient's blood pressure (BP) while the patient is lying down may yield more information about their cardiovascular risk than taking the reading while the patient is sitting upright, new preliminary research suggests.

An analysis of data from a long-running Atherosclerosis Risk in Communities (ARIC) study of more than 11,000 adults showed that those who had hypertension while supine were at elevated risk for cardiovascular disease (CVD) independently of their having hypertension while seated.

"If blood pressure is only measured while people are seated upright, cardiovascular disease risk may be missed if not measured also while they are lying supine on their backs," lead investigator Duc M. Giao, a researcher and a fourth-year MD student at Harvard Medical School, Boston, said in a news release.

Giao presented the findings at the Hypertension Scientific Sessions (HYP) 2023, in Boston, Massachusetts.

Take Seated and Supine BP in Clinic?

Hypertension while asleep is strongly associated with CVD and death, but whether hypertension detected in clinic while the patient is lying flat is a risk factor for CVD independently of the patient's BP while seated remains unclear.

To investigate, Giao and colleagues reviewed health data for 11,369 adults (mean age, 54 years; 56% women; 25% Black persons) from the longitudinal ARIC study. None had a history of coronary heart disease (CHD), heart failure (HF), or stroke at baseline.

As part of the study, data on supine and seated BP were obtained during the enrollment period at ARIC visit 1, which took place between 1987 and 1989. Both seated and supine hypertension were defined as systolic BP ≥130 mm Hg or diastolic BP ≥80 mm Hg.

The data revealed that 16% of those without seated hypertension had supine hypertension, while 74% of those with seated hypertension had supine hypertension.

Despite adjusting for seated hypertension, during a median follow-up of 25 to 28 years, supine hypertension was associated with an increased risk for incident CHD, HF, stroke, fatal CHD, and all-cause mortality.

Table. Risk for CVD Events With Supine BP

Outcome Adjusted hazard ratio (95% CI)
CHD 1.60 (1.45 – 1.76)
HF 1.83 (1.68 – 2.01)
Stroke 1.86 (1.63 to 2.13)
Fatal CHD 2.18 (1.84 to 2.59)
All-cause mortality 1.43 (1.35 to 1.52)

The results did not differ by antihypertensive medication use (P > .05).

For patients who had hypertension while supine but not while seated, elevations in risk were similar to those of peers who had hypertension while both seated and supine.

"Our findings suggest people with known risk factors for heart disease and stroke may benefit from having their blood pressure checked while lying flat on their backs," Giao said in the conference news release.

"Efforts to manage blood pressure during daily life may help lower blood pressure while sleeping. Future research should compare supine blood pressure measurements in the clinic with overnight measurements," Giao added.

Busy Clinical Practice

Commenting on the study for | Medscape Cardiology, Wanpen Vongpatanasin, MD, clinical chair for the conference, said, "This finding highlights the importance of sustained control of BP in all body positions."

She noted that many population-based studies have shown that nighttime BP independently predicts CV outcomes. "It's unclear whether the timing of BP measurement (night vs day) or the position (as most people sleep in supine position at night) explains this phenomenon."

The study by Giao and colleagues suggests that "supine BP may be one explanation, as it has as much impact on long-term CV outcome as seated BP," said Vongpatanasin, professor of internal medicine and director of the Hypertension Section, Cardiology Division, UT Southwestern Medical Center in Dallas, Texas.

However, "in busy clinical practice, it is impossible to do both seated and supine, as well as standing BP," said Vongpatanasin.

"Additional studies are needed to determine what is considered to be the cutoff for normal supine BP and how to incorporate it in management of hypertension," she added.

The study had no commercial funding. Giao and Vongpatanasin have disclosed no relevant financial relationships.

Hypertension Scientific Sessions (HYP) 2023: Abstract 452. Presented September 9, 2023.

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