- A study published in the American Journal of Hypertension found that in-home blood pressure (BP) monitors weren't accurate within five mmHg about 70 per cent of the time. These devices were off the mark by 10 mmHg about 30 per cent of the time.
These measures of BP are clinically significant, the researchers said, which may pose a problem for patients monitoring their blood pressure for clinical reasons. If devices aren’t helping patients in ways they’re supposed to, then a more critical assessment of these devices is needed, the study suggests.
According to the research team, many physicians believe that in-home BP monitoring provides the advantages of patient convenience, self-management, and therapeutic adherence to measurement. However, many of these devices are sold without formal validation of accuracy to elderly patients with cardiovascular conditions.
To find out if these devices provided adequate BP measures, the team enrolled 85 patients that owned and used an oscillometric home BP monitor. The patients also had the same average BP levels, which gave the team a benchmark to test device accuracy.
After testing the devices and finding several inaccuracies in their BP recordings, the team suggested that administering more than one BP test is the best approach when monitoring patients with significant hypertension.
"Compare the blood pressure machine measurement with a blood pressure measurement in clinic before exclusively relying upon home blood pressure readings," advised medical researcher Jennifer Ringrose, who led the study.
"What's really important is to do several blood pressure measurements and base treatment decisions on multiple readings. Taking home readings empowers patients and is helpful for clinicians to have a bigger picture rather than just one snapshot in time."
The results of this study follow a report that found consumer-grade fitness devices monitoring heart rate are often incorrect, varying from clinical measurements by upwards to 20 beats per minute. Home-based monitoring devices aren’t necessarily required to match clinical standards of measurement.
The researchers noted similar difficulties with trying to determine why the inaccuracies are occuring in home BP monitors. A major reason for this that outside parties don't have access to the various formulas the devices used to determine blood pressure, because this type of information is considered proprietary and kept secret by the manufacturer.