According to the World Health Organization (WHO), hypertension is one of the major risk factors for death worldwide. The global adult population with hypertension is approximately 113 million, with an estimated prevalence of 18-27%. Hypertension is associated with stroke and other cardiovascular diseases, thus early detection and treatment critical. National guidelines of the Japanese, European, and American Hypertension Society recommend that home blood pressure and clinic blood pressure test results be applied together when diagnosing hypertension, emphasizing the importance of blood pressure monitoring in daily life. In addition, according to the Ohasama cohort study and the Finn-Home study, blood pressure measured in daily life was more predictive of cardiovascular disease than the office blood pressure.~There are invasive and non-invasive methods for blood pressure monitoring. The invasive method measures blood pressure using a pressure sensor by inserting a catheter into a blood vessel, and the non-invasive method measures blood pressure by sensing sound or vibration while applying pressure using a cuff. Invasive blood pressure tests can continuously measure blood pressure and are accurate, but there is a high risk of side effects such as distal ischemia, bleeding, thrombosis, infection, etc and is not available for a daily life. Non-invasive blood pressure test methods such as auscultatory measurement and oscillometric method are simpler than invasive methods, but it has limitations in measuring blood pressure continuously and observing long-term variations.~The photoplethysmography (PPG) method makes it possible to measure blood pressure without a cuff, enabling people to check and monitor blood pressure in daily life for a long time. It has been reported that the wavelength and amplitude of the PDW signal collected from the finger show a high correlation (0.92) with the PDP signal collected from the wrist. This suggests that the blood pressure accuracy of measuring blood pressure with PPG signals collected from the finger will not differ significantly from that measured from the wrist.~Sky Labs has developed 'CART-I plus' that can measure blood pressure in daily life without a cuff. 'CART-I plus' is a ring-type device that applies the principle of PPG technology to measure blood flow through finger veins. This clinical trial was designed in accordance with the ISO 81060-2:2018 standard to evaluate the accuracy of blood pressure estimated by 'CART-I plus'.
The goal of this clinical trial is to evaluate how accurately the CART-I plus developed by Sky Labs can measure blood pressure. The primary endpoint of this clinical trial is accuracy (mmHg) of 'CART-I plus' which is obtained by calculating mean error and standard deviation of blood pressure differences between 'CART-I plus' and the gold standard for non-invasive method, auscultatory method. The reference readings are taken by auscultatory method using a sphygmomanometer and a stethoscope. The mean errors and standard deviations are calculated both sample- and subject-wise.