Validation of the A&D wrist-cuff UB-511 (UB-512) device for self-measurement of blood pressure

Nonvalidated Home Blood Pressure Devices Dominate the Online Marketplace in Australia: Major Implications for Cardiovascular Risk Management

Self-home blood pressure (BP) monitoring is recommended to guide clinical decisions on hypertension and is used worldwide for cardiovascular risk management. People usually make their own decisions when purchasing BP devices, which can be made online. If patients purchase nonvalidated devices (those not proven accurate according to internationally accepted standards), hypertension management may be based on inaccurate readings resulting in under- or over-diagnosis or treatment. This study aimed to evaluate the number, type, percentage validated, and cost of home BP devices available online. A search of online businesses selling devices for home BP monitoring was conducted. Multinational companies make worldwide deliveries, so searches were restricted to BP devices available for one nation (Australia) as an example of device availability through the global online marketplace. Validation status of BP devices was determined according to established protocols. Fifty nine online businesses, selling 972 unique BP devices were identified. These included 278 upper-arm cuff devices (18.3% validated), 162 wrist-cuff devices (8.0% validated), and 532 wrist-band wearables (0% validated). Most BP devices (92.4%) were stocked by international e-commerce businesses (eg, eBay, Amazon), but only 5.5% were validated. Validated cuff BP devices were more expensive than nonvalidated devices: median (interquartile range) of 101.1 (75.0-151.5) versus 67.4 (30.4-112.8) Australian Dollars. Nonvalidated BP devices dominate the online marketplace and are sold at lower cost than validated ones, which is a major barrier to accurate home BP monitoring and cardiovascular risk management. Before purchasing a BP device, people should check it has been validated at https://www.stridebp.org.

An analysis of blood pressure measurement in a primary care hospital in Swaziland

Background

Measurement of blood pressure (BP) is done poorly because of both human and machine errors.

Aim

To assess the difference between BP recorded in a pragmatic way and that recorded using standard guidelines; to assess differences between wrist- and mercury sphygmomanometer-based readings; and to assess the impact on clinical decision-making.

Setting

Royal Swaziland Sugar Corporation Mhlume hospital, Swaziland.

Method

After obtaining consent, BP was measured in a pragmatic way by a nurse practitioner who made treatment decisions. Thereafter, patients had their BP re-assessed using standard guidelines by mercury (gold standard) and wrist sphygmomanometer.

Results

The prevalence of hypertension was 25%. The mean systolic BP was 143 mmHg (pragmatic) and 133 mmHg (standard) using a mercury sphygmomanometer; and 140 mmHg for standard BP assessed using wrist device. The mean diastolic BP was 90 mmHg, 87 mmHg and 91 mmHg for pragmatic, standard mercury and wrist, respectively. Bland Altman analyses showed that pragmatic and standard BP measurements were different and could not be interchanged clinically. Treatment decisions between those based on pragmatic BP and standard BP agreed in 83.3% of cases, whilst 16.7% of participants had their treatment outcomes misclassified. A total of 19.5% of patients were started erroneously on anti-hypertensive therapy based on pragmatic BP.

Conclusion

Clinicians need to revert to basic good clinical practice and measure BP more accurately in order to avoid unnecessary additional costs and morbidity associated with incorrect treatment resulting from disease misclassification. Contrary to existing research, wrist devices need to be used with caution.

Evaluation scale to assess the accuracy of cuff-less blood pressure measuring devices

OBJECTIVE

The call for early detection of hypertension and cardiac events creates a heavy demand for devices that can be used for blood pressure (BP) monitoring at home and in ambulatory settings. An emerging type of BP monitors without an occluding cuff has drawn great attentions for this application because it is comfortable and capable of providing continuous readings. For the development the cuff-less devices, it is crucial for the clinicians and engineers to joint efforts in establishing an evaluation standard.

METHODS

This study attempts to contribute to its initiation in two ways. First, a new distribution model for measurement differences between the test device and the reference was proposed. We verified the model using evaluation results from 40 devices, of which 80% of the American Association for the Advancement of Medical Instrumentation and British Hypertension Society reporting results were in agreement, as compared with 50%, if the original normal model was used. We further tested a cuff-less device on 85 patients for 999 datasets and found that the differences between the proposed distribution and that of the device were nonsignificant for systolic BP measurements (Kolmogorov-Smirnov = 0.036, P = 0.15). Second, some evaluation scales were studied for their capability to assess the accuracy of cuff-less devices. For mean absolute difference, a map was developed to relate it with the criteria of American Association for the Advancement of Medical Instrumentation, British Hypertension Society, and European Society of Hypertension protocols, on the basis of the proposed distribution model; for mean absolute percentage difference, it is prominent in evaluating devices that have measurement errors often increasing with BP, which is an issue has not been fully explored in existing standards.

CONCLUSION

This study focused on the statistical aspect of establishing standard to assess the accuracy of cuff-less BP measuring devices. The results of our study on the validation reports of various cuff-based devices and an experimental study on a cuff-less device showed that the t4 distribution is better than the normal distribution in portraying the underlying error distribution of both kinds of devices. Moreover, based on both the theoretical and experimental studies, mean absolute difference or mean absolute percentage difference is recommended as continuous scale to assess the accuracy of cuff-less devices for their own distinctive advantages.

Can validated wrist devices with position sensors replace arm devices for self-home blood pressure monitoring? A randomized crossover trial using ambulatory monitoring as reference

BACKGROUND

Electronic devices that measure blood pressure (BP) at the arm level are regarded as more accurate than wrist devices and are preferred for home BP (HBP) monitoring. Recently, wrist devices with position sensors have been successfully validated using established protocols. This study assessed whether HBP values measured with validated wrist devices are sufficiently reliable to be used for making patient-related decisions in clinical practice.

METHODS

This randomized crossover study compared HBP measurements taken using validated wrist devices (wrist-HBP, Omron R7 with position sensor) with those taken using arm devices (arm-HBP, Omron 705IT), and also with measurements of awake ambulatory BP (ABP, SpaceLabs), in 79 subjects (36 men and 43 women) with hypertension. The mean age of the study population was 56.7 +/- 11.8 years, and 33 of the subjects were not under treatment for hypertension.

RESULTS

The average arm-HBP was higher than the average wrist-HBP (mean difference, systolic 5.2 +/- 9.1 mm Hg, P < 0.001, and diastolic 2.2 +/- 6.7, P < 0.01). Twenty-seven subjects (34%) had a > or =10 mm Hg difference between systolic wrist-HBP and arm-HBP and twelve subjects (15%) showed similar levels of disparity in diastolic HBP readings. Strong correlations were found between arm-HBP and wrist-HBP (r 0.74/0.74, systolic/diastolic, P < 0.0001). However, ABP was more strongly correlated with arm-HBP (r 0.73/0.76) than with wrist-HBP (0.55/0.69). The wrist-arm HBP difference was associated with systolic ABP (r 0.34) and pulse pressure (r 0.29), but not with diastolic ABP, sex, age, arm circumference, and wrist circumference.

CONCLUSIONS

There might be important differences in HBP measured using validated wrist devices with position sensor vs. arm devices, and these could impact decisions relating to the patient in clinical practice. Measurements taken using arm devices are more closely related to ABP values than those recorded by wrist devices. More research is needed before recommending the widespread use of wrist monitors in clinical practice. American Journal of Hypertension doi:10.1038/ajh.2008.176American Journal of Hypertension (2008); 21, 7, 753-758. doi:10.1038/ajh.2008.176.