Accuracy of Apple Watch to Measure Cardiovascular Indices in Patients With Chronic Diseases: A Cross Sectional Study

Introduction:

Assessment of the heart rate (HR) is an essential process to determine proper exercise training intensity. (1) Utilization of the 12-leads electrocardiogram (ECG) is considered most objective heart rate assessment procedure. Polar chest strap arises as an alternative to the ECG when it is not accessible to use it outside the laboratories. The Polar chest strap proved valid and reliable instrument when tested against the ECG in healthy subjects (2-4) and patients with cardiac diseases (5) at rest and during training. Monitoring the resting as well as the post-training heart rate (heart rate recovery) is essential because it helps predicting the cardiopulmonary fitness level as well as the mortality risk among evaluated personnel. (6)

Diabetes mellitus is a rapidly growing non-communicable chronic disease worldwide, becoming one of the most alarming health problems in the 21st century. The overall estimated prevalence of diagnosed diabetes in 2018 was 26.9 million US subject of all ages (8.2% of the US population) (7) The International Diabetes Federation (IDF) has estimated the total number of persons with DM across the world will rise from 536.6 million in 2021 to 783.2 million by 2045, with about 94% of the increase in the number of subjects with diabetes by 2045 will be within the low and middle-income countries. The global incidence also projected to increase from 16.3% in 2021 to 19.2% by 2025 in middle- and low-income countries. The prevalence of diabetes in adults (20-79 years old) in the Middle East and North Africa was estimated to be 16.2% compared to 19.3% in 2045. (8) Hypertension possess significantly increased public health risk and population challenge. The prevalence of hypertension was 6.0, 4.2 and 4.9% in male, female and all subjects, respectively. (9) Hypertension prevalence is increasing in KSA, the rate exceeds 25% among the adult Saudi subjects. Monitoring the hypertension-related disturbances is an urgent concept to prevent its organs-damaging. (10) Regional study at Majmaah, Saudi Arabia reported that the hypercholesterolemia prevalence was 45.3%, with no significant difference between both genders. (11) A study by Al-Nozha et al., reported that the hyperlipidemia continues reaching higher prevalence rate recently. The hypercholesterolemia prevalence among the 30-70 years old subjects reached 54.9% and 53.2% for males and females respectively, Hypertriglycemia prevalence was 47.6% in male compared to 33.7% in females. (12) More recently; a study by reported that the prevalence of Hypercholesterolemia among Saudi population ≥ years old is around 12.5%, with males have higher rate (56.7%) compared to females who have lower s rate (43.3%). Close monitoring of the vital signs and cardiovascular variables in patients with chronic non-communicable diseases is indicated since many harmful consequences can be prevented via increasing community awareness and education. (13) Diabetes Mellitus is chronic debilitating disorder requires well-organized efforts and continuous monitoring to limit the impact of disease-associated hazards and long-term complications. (14) The process of SpO2 evaluation is important because it indirectly reflects the subject's organs oxygen requirements. The traditional SpO2 measuring procedure is invasive and painful, requiring collection and assay of arterial blood sample using a blood gas analyzer. (15) Previous trials proposed evaluating the SpO2 non-invasively using simple procedure, with keeping maximum accuracy. (16) Pulse oximetry is a well-known noninvasive instrument used for monitoring and evaluation of SpO2). (17) Routine and frequent screening of patients with chronic diseases is recommended especially with age over 50 years and presence of other comorbidities as HTN and hyperlipidemia. (18) Pulse oximetry is used to measure the level of the SpO2, with low blood flow is associated with lower SpO2. (19) The HR is tightly and linearly correlated with the oxygen consumption at specified time point.(20) Monitoring of other vital variables as the oxygen saturation (SpO2) is recommended in patients suffering hypoxia to improve their survival, (21) as in post-operative and post-arrest cardiac patients, (22) with the pulse oximeter is the widely used instrument to evaluate the SpO2 because of accuracy and ease of application. (23) Quiet recently; the Apple smart watch appeared as a new tool to measure the HR. all the Apple watch versions can monitor the HR, but the blood SpO2 can be only measured by only the latest 6 and 7 versions. The concept of utilizing the Apple watch to measure the HR depends on the Photoplethysmography (PPT) non-invasive measurement procedure applied using wrist-worn watch that continuously monitors both heart beats and blood color changes over time. The PPT is a commonly used approach to measure the cardiac output, blood pressure and SpO2 in verities of medical instruments, (24) that can help discovering the cardiovascular insults and complications at early stages. (25) Implemented new technology and updated features that enable the Apple watch to monitor the HR is available only in updated series-6 and 7. Very limited number of studies evaluated the validity of the Apple watch against pulse oximeter in measuring the SpO2 (the Spo2 was evaluated in 23 patients with chronic obstructive pulmonary disease, 61 patients with interstitial lung diseases and 16 health control subjects). the Apple watch results showed strong positive correlations with that of the pulse oximeter (r=0.81, P<0.0001), furthermore; this study recommended testing the Apple watch validity for measuring the SpO2 in other groups of patients. (26) The Apple watch is a smart instrument with advanced technology measuring the Spo2 and heart rate but its validity in patients with chronic diseases including patients with diabetic mellites, hypertension and hyperlipidemia is still unknown. Therefore, this will be the first study to evaluate the Apple watch accuracy and validity in measuring the Spo2 and heart rate in patients with chronic diseases including diabetic mellitus, hypertension, hyperlipidemia.

Method:

A cross sectional study will be conducted, ninety-five chronic patients will be invited to participate in this study. The study design will be in form of 3-groups: first group will include 35 patients with diabetes and the second group will include 35 patients with hypertension. The third group will be around 35 patients with hyperlipidemia. The distribution of patients and number of groups will be based on the availability of the patients with chronic non-communicable diseases at Umm Al-Qura University Medical Center. All participants in this study will wear the Polar chest strap HR and the Apple Watch at rest, during short session of mild to moderate intensity exercise [50-70% (maximum heart rate-Resting heart rate) + resting heart rate] for 15 minutes and after exercise. The pulse oximeter will be used at rest (pre) and after exercise.