Introduction: Blood pressure (BP) measurement following 5-10 minutes of seated rest during an office visit is recommended to more accurately determine a person’s BP. Alternatively, home BP readings are often recommended as they better reflect cardiovascular risk than does office BP, therefore suggesting a single BP measure in the home setting is an accurate reflection of an individual’s usual BP.
Hypothesis: By analyzing a dataset of more than 16 million home BP measurements we aim to determine the stability of serial BP measurements in the home setting.
Methods: We analyzed home BP measurements collected with Withings Wireless Blood Pressure monitors involving more than 56 thousand people. We focus on Intervals of Consecutive Measurements (ICMs), i.e., intervals of time in which a subject repeated the BP measure every 10 minutes or less. We computed the expected decrease in systolic and diastolic BP as a function of time from 1 to 30 minutes of ICM.
Results: We analyzed more than 4 million ICMs with an interval between measurements of at least 1 minute, in a population with an average age of 54.7 and 20.5% female. The systolic and diastolic BPs for the entire population ranged from 98 to 160 and 60 to 110, respectively. We computed the average decrease in BP (Figure) after the first measurement of an ICM. After 5 minutes there was a decrease of 6.0 mmHg and by 10 minutes 6.6 mmHg for the systolic BP, and 3.5 and 4.0 mmHg for diastolic BP at the same times. By 25 minutes after the initial read the expected decrease reaches 7.8 mmHg systolic, and 5.2 mmHg diastolic. Correspondingly, the heart rate slightly decreased by ~2 beats per minute. In the figure, we also show the 95% confidence interval.
Conclusions: Home BP decreases significantly, similarly to in-office BP, in the minutes after the initial measurement. We showed for the first time that the first home measurement likely over-estimates the “true” resting BP, providing an initial evidence for future guidelines on home BP monitoring.