How accurate is the wrist style BP cuff folks tend to buy from the chemist/online?

March 23, 2020

Uy Hoang

On behalf of the Oxford COVID-19 Evidence Service Team
Centre for Evidence-Based Medicine, Nuffield Department of Primary Care Health Sciences
University of Oxford

Correspondence to uy.hoang@phc.ox.ac.uk

Lay Summary by Mandy Payne, Health Watch

Verdict

No specific evidence is yet available on the use of wrist BP machines or home BP monitoring in patients with COVID-19 or other acute respiratory illness.  Wrist blood pressure (BP) machines are accurate to within -2.5 to 3.5mmHg of upper arm BP machines, [1] and achieve correct BP classification in over 80% of people compared to ambulatory BP monitoring.

Background

Based on initial reports from China, and subsequent evidence that hypertension may be associated with increased risk of mortality in hospitalized COVID-19 infected subjects, there have been questions about the role of home BP monitoring in people with hypertension who need to self-isolate. Especially the accuracy and reliability of wrist BP machines sold in pharmacies.

Summary of findings from the most useful papers. [2]

The only clinical trial-specific to wrist BP devices found the categorization of subjects as normotensive or hypertensive, using the wrist device in subjects without specific training, achieved a correct classification in 84% of cases with a position sensor (81% without) in comparison to ambulatory BP monitoring (ABPM)[3].

• The difference with regard to systolic BP between the mercury and the wrist BP devices was -2.5+/-5.3 mmHg, which is within the AAMI standard.
• The mean values of the differences between the mercury and ABPM devices remained under 5 mmHg, their standard deviation was above +/- 8 mmHg.
• For diastolic BP, the difference between all of the devices was below 5+/-8 mmHg[1].

International guidelines generally recommend BP should be measured at the upper arm for home monitoring in preference to finger-cuff devices and wrist-cuff devices.[4] This recommendation is particularly important in patients with obesity and high blood pressure, where their accuracy has been questioned. [5, 6]. However, wrist monitors are included in the NICE validated BP monitoring devices and are likely to provide reasonably accurate home BP assessment in most people [7].

Disclaimer:  the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited should be checked. The views expressed in this commentary represent the views of the authors and not necessarily those of the host institution, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.

Author

Uy Hoang is a Research Fellow Clinical Informatics and Health Outcomes Research Group at the Nuffield Department of Primary Carehealth Sciences

Search Strategy

Population – General population, Intervention – Home blood pressure monitoring (especially wrist BP devices), Comparison – Ambulatory Blood Pressure Monitoring, Outcome – Blood pressure reading.

Databases search included Embase from 1974 to present, Medline 1946 to present and the Cochrane Library of systematic reviews. The following keywords were used – blood pressure monitoring, blood pressure monitor, blood pressure measurement; Self Care, home, at. home; Sensitivity, Specificity, diagnostic adjacent to (accura* or performance or utility or specific* or sens*). 104 research articles found (of which there were 11 non-systematic literature reviews) and 37 clinical trials (1 of which looked at wrist BP devices). 4 studies were useful for this reply.

References

Altunkan, S., Y. Genc, and E. Altunkan, A comparative study of an ambulatory blood pressure measuring device and a wrist blood pressure monitor with a position sensor versus a mercury sphygmomanometer. Eur J Intern Med, 2007. 18(2): p. 118-23.
Cohen, J.F., et al., STARD 2015 guidelines for reporting diagnostic accuracy studies: explanation and elaboration. BMJ Open, 2016. 6(11): p. e012799.
Uen, S., et al., Evaluation of the performance of a wrist blood pressure measuring device with a position sensor compared to ambulatory 24-hour blood pressure measurements. Am J Hypertens, 2002. 15(9): p. 787-92.
Imai, Y., et al., Japanese society of hypertension (JSH) guidelines for self-monitoring of blood pressure at home. Hypertens Res, 2003. 26(10): p. 771-82.
Azaki, A., et al., Questionable accuracy of home blood pressure measurements in the obese population – Validation of the Microlife WatchBP O3((R)) and Omron RS6((R)) devices according to the European Society of Hypertension-International Protocol. Vasc Health Risk Manag, 2017. 13: p. 61-69.
O’Brien, E., et al., Practice guidelines of the European Society of Hypertension for clinic, ambulatory and self blood pressure measurement. J Hypertens, 2005. 23(4): p. 697-701.
National Institute for Health and Care Excellence. Hypertension in adults: diagnosis and management. NICE Guideline (NG) 136, 2019. www.nice.org.uk/guidance/ng136