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Hypertension is a global public health issue and is closely related to chronic kidney disorder (CKD). In people with CKD, strict monitoring of blood pressure is an important part of therapy.
The aim of this research was to validate the iHealth Track blood pressure monitoring device for patients with CKD according to the European Society of Hypertension International Protocol 2010 (ESH-IP2).
In total, 33 patients who received hemodialysis in Plasencia participated in the study. There were 9 successive measurements made, which conformed to the ESH-IP2. We calculated the differences between the standard reference device (Omron M3 Intellisense) and the test device (iHealth Track) for blood pressure and heart rate values. For 99 total comparisons of paired measurements, we classified differences into various categories (≤5 mmHg, ≤10 mmHg, and ≤15 mmHg for blood pressure; ≤3, ≤5, and ≤8 beats per minute for heart rate).
In 90 of 99 systolic blood pressure and 89 of 99 diastolic blood pressure comparisons between the devices, measurement differences were within 5 mmHg. In 81 of 99 heart rate comparisons between the devices, measurement differences were within 3 beats per minute. The mean differences between the test and reference standard measurements were 3.27 (SD 2.99) mmHg for systolic blood pressure, 3.59 (SD 4.55) mmHg for diastolic blood pressure, and 2.18 (SD 2.75) beats per minute for heart rate. We also observed that for both systolic and diastolic blood pressure, 31 of 33 participants had at least two of three comparisons between the devices with measurement differences less than 5 mmHg. For heart rate, 28 of 33 patients had at least two of three comparisons between the devices with measurement differences less than 3 beats per minute.
To our knowledge, this is the first study to show that iHealth Track meets the requirements of the ESH-IP2 in patients with CKD. Therefore, the iHealth Track is suitable for use in renal patients.
Chronic kidney disorder (CKD) is a syndrome defined by persistent alterations in renal function or structure that cause complications in a patient's health. Some of the structural anomalies may be tumors, cysts, malformations, or atrophies. In addition, renal dysfunction can be manifested through alterations in the output or grade of urine, increased risks of intellectual disabilities in children, edema, and hypertension [
In fact, the diseases most related with CKD are hypertension and diabetes, especially in high- and middle-income countries [
The interaction between CKD and hypertension is complex and increases the probability of cerebrovascular and cardiovascular problems [
Monitoring of BP should be done with devices that are easy to use and accurate [
The study protocol was approved by the Institutional Local Research and Ethical Committee (Universidad de Extremadura, Badajoz, Spain; record number 152/2019). In conducting this study, we complied with the ethical principles of the Declaration of Helsinki [
The standard device we used for reference was the Omron M3 Intellisense (Omron Healthcare, Kyoto, Japan), which has been validated according to the International Protocol for the general population [
The test device was the iHealth Track automatic appliance with serial number KN-550BT (iHealthLabs Europe, Paris, France), which registers brachial BP with the oscillometric protocol. It detects BP between the range of 0 mmHg to 300 mmHg (measuring precision ±3 mm Hg) and HRs within the range of 40 to 180 beats per min (measurement precision ±5%). The device’s arm cuff is 22 to 42 cm around.
The device’s liquid crystal display screen shows the measured systolic (S) BP, diastolic (D) BP, and HR values. The device unit has enough memory for 99 recordings. Additionally, this device unit can be used with Apple Bluetooth 4.0 devices and certain Android Bluetooth 4.0 cellular phones through an application named Health MyVitals. This means that BP and HR data can be stored on wireless devices connected to iHealth Track and then displayed graphically.
We recruited patients with CKD who attended the Fresenius Medical Care dialysis clinic in Plasencia, Spain. A total of 33 patients who met the selection criteria participated. The inclusion criteria were adults 25 years of age or older that received hemodialysis. We sought at least 10 male participants and 10 female participants. The exclusion criteria, which were created according to the ESH-IP2 [
The professional validation team consisted of 2 nurses with senior experience (more than 6 years) in BP measurement. The measurement area was correctly conditioned to a suitable temperature, and factors that could affect the records, such as noise or distractions, were removed [
After dialysis, each patient first reported information regarding their sex, age, height, and dry weight. In addition, we calculated participants’ BMI using Quetelet´s index in kg/m2. The circumference of the patient’s arm was measured to ensure that the cuff size was adequate.
Next, patients sat in the measurement room and BP measurements were started after a 10- to 15-minute rest period. Each patient was seated in a standard-size plastic chair with a backrest and armrests.
In total, 9 consecutive measurements were made on each participant with the Omron M3 Intellisense (5) and the iHealth Track (4) as follows [
(BPA): input BP, by the standard device unit
(BPB): device BP detection by the test device unit
(BP1): standard device unit
(BP2): test device unit
(BP3): standard device unit
(BP4): test device unit
(BP5): standard device unit
(BP6): test device unit
(BP7): standard device unit
During the measurements, participants remained calm, quiet, seated, and still. Participants kept their backs straight and feet on the floor in a parallel position (ie, without crossing their legs). They rested their arms on a flat surface with their palms facing upwards and their elbows slightly flexed so that their fists were at the height of their hearts.
BP records were made at heart level on the right arm in 31 participants and on the left arm in 2 participants (because of an arteriovenous fistula on the right arm). The standard cuff size (22-32 cm) for the Omron M3 Intellisense was used for all men (20). For women, the standard cuff (22-32 cm) was used for 11 participants, and the large cuff (32-42 cm) was used for 2 participants. Since the iHealth Track has only one cuff size (22-42 cm), all measurements were taken with it. The interval between one measurement and the next was 30 to 60 seconds [
All measurements were made for each participant during their hemodialysis appointment, after the dialysis was complete. The relative values were then used to calculate the mean difference between the reference device readings and the test device readings. All participants were receiving hemodialysis in the Fresenius Medical Care dialysis clinic in Plasencia.
We analyzed the data with the software SPSS Statistics, version 19.0 (IBM, Armonk, New York). We reported the findings as mean (SD).
According to the ESH-IP2, the accuracy of a device is based on a comparison between the test device (iHealth Track) and the standard reference device (Omron M3 Intellisense) measurements. For each participant, we first compared measurements BP2, BP4, and BP6 with measurements BP1, BP3, and BP5, respectively, and then compared measurements BP3, BP5, and BP7 with each other. The most favorable comparisons were used.
In our comparisons, we classified differences for both SBP and DBP, separately, by whether paired values were within 5, 10, or 15 mmHg [
Moreover, we produced Bland-Altman plots [
Of the 34 participants we recruited, 33 completed the study successfully (one was excluded for device failure). The 33 participants included 20 men and 13 women.
Participants’ biometric characteristics.
Variables | Total sample (N=33) | Males (N=20) | Females (N=13) | ||||
|
Mean (SD) | Range | Mean (SD) | Range | Mean (SD) | Range | |
Age (years) | 71.24 (11.76) | 47.0-88.0 | 70.25 (11.42) | 47.0-85.0 | 72.77 (12.57) | 47.0-88.0 | |
Weight (kg) | 70.48 (15.87) | 46.0-101.0 | 70.18 (12.95) | 47-100.0 | 70.94 (20.16) | 46.0-101.0 | |
Height (cm) | 162.24 (9.87) | 141.0-180.0 | 167.10 (4.58) | 160.0-180.0 | 154.77 (11.24) | 141.0-174.0 | |
BMI (kg/m2) | 26.95 (6.72) | 18.0-44.0 | 25.07 (4.08) | 18.0-33.0 | 29.84 (8.90) | 19.0-44.0 | |
Arm circumference (mm) | 265.0 (33.12) | 220.0-350.0 | 264.75 (26.13) | 220.0-320.0 | 265.0 (33.12) | 220.0-350.0 |
The iHealth Track BP device validation results were taken in accordance with the ESH-IP2. The mean differences between the reference standard and test devices were 3.27 (SD 2.99) mmHg for SBP and 3.59 (SD 5.28) mmHg for DBP. In 90 out of 99 SBP and 89 out of 99 DBP comparisons between the devices, measurement differences were within 5 mmHg, exceeding the ESH-IP thresholds (>72 comparisons for SBP and >64 comparisons for DBP). Additionally, in 95 out of 99 SBP and 94 out of 99 DBP comparisons between the devices, measurement differences were within 10 mmHg, also exceeding the ESH-IP thresholds (>86 comparisons for SBP and >80 comparisons for DBP). Moreover, in 98 out of 99 SBP and 94 out of 99 DBP comparisons between the devices, measurement differences were within 15 mmHg, which again surpasses the ESH-IP thresholds (>95 comparisons for SBP and >92 comparisons for DBP). Therefore, the iHealth Track passed part 1 of the validation protocol for BP monitoring.
Regarding part 2 of the ESH-IP2, 31 out of 33 participants had at least two of the three comparisons between devices with measurement differences within 5 mmHg for both SBP and DBP, exceeding the ESH-IP threshold (>23 participants). One participant had all three comparisons for both SBP and DBP with measurement differences greater than 5 mmHg, which is less than the ESH-IP maximum of 3 participants. Given these results, the iHealth Track also passed part 2 of the validation protocol for BP. Thus, because the iHealth Track passed parts 1 and 2 of the BP validation protocol, it passed part 3 of the protocol, overall validation.
The validation findings for the iHealth Track HR monitoring device were taken according to the ESH-IP2. The mean difference between the reference standard and test devices was 2.18 BPM (SD 2.75). In comparisons between devices, 81 out of 99 pairs of measurements were within 3 BPM, 91 out of 99 were within 5 BPM, and 96 out of 99 were within 8 BPM. These results indicate that the iHealth Track passed part 1 of the validation protocol for HR.
Regarding part 2 of the ESH-IP2, 28 out of 33 patients had at least two of three comparisons between devices with measurement differences within 3 BPM, which exceeds the ESH-IP threshold (>23 participants). Only 2 participants had all three HR comparisons with measurement differences greater than 3 BPM, which is less than the ESH-IP maximum of 3 participants. Therefore, the iHealth Track passed part 2 of the HR validation protocol and, consequently, part 3 (overall validation) as well.
The Bland-Altman graphs (
Bland-Altman graph of systolic blood pressure differences between the iHealth Track and the Omron M3.
Bland-Altman graph for diastolic blood pressure differences between the iHealth Track and the Omron M3.
Bland-Altman graph for heart rate differences between the iHealth Track and the Omron M3.
This study is the first to validate the accuracy of the iHealth Track device for BP and HR recordings in patients with CKD. The results indicate that the iHealth Track, as used in renal patients, passed the ESH-IP2 validation requirements. We previously validated the iHealth Track device for the general population following ESH-IP2 [
This study showed two limitations. Although the iHealth Track has been validated in the general population and now in patients with CKD, we cannot necessarily extrapolate our results to other specific populations. In addition, patients with CKD have stiffer arteries than other people [
The ESH-IP2 for home BP monitoring highlights the need for specific validation in patients with end-stage renal disease [
However, there are few devices that have been validated in patients with renal disease [
The purpose of the ESH-IP2 was to simplify the previous protocols of the British Hypertension Society (BHS) [
Our study is the first to show that the iHealth Track device meets the requirements of ESH-IP2 in patients with CKD. Future versions of the ESH-IP should include explicit criteria for validation in specific populations. Validation of this device would be valuable in other specific populations such as pregnant women, older adults, and patients with arrhythmias.
Association for the Advancement of Medical Instrumentation
British Hypertension Society
blood pressure
beats per minute
chronic kidney disorder
diastolic
Hypertension International in European Society protocol 2010
heart rate
International Organization for Standardization
systolic
We thank the patients and medical staff from the Fresenius Medical Care clinic in Plasencia, especially Dr Alejandro Cives, nephrologist.
None declared.