Correlation of Systolic and Diastolic Blood Pressure in Measuring Blood Pressure Using Validated Digital Wrist...

Wrist-cuff blood pressure (wBP) monitors in the market have gained popularity due to their cost, portability, acceptability, and accessibility. Although wide variability in wrist versus the standard arm BP (aBP) monitor values has been reported, comparative investigations in a real-world setting has not been fully elucidated. This study was undertaken to correlate systolic and diastolic BP using wBP versus the standard aBP monitors, to determine discrepancies, if any, and to formulate recommendations for its use. Adult subjects with normal, mild, or moderate hypertension randomly recruited in the investigators' clinics were included. Complete medical history and physical examination were done, and standard positioning for BP measurements was followed. Validated wrist BP (Omron, HEM6161) and validated aBP (Omron, HEM7156) monitors were used. The statistical data were analyzed with R (ver 4.3.2) and MedCalc Statistical Software (Version 22.021). Correlation between wBP and aBP was determined using Passing-Bablok regression and Lin's concordance correlation coefficient. Bland-Altman analysis was applied to determine if the wBP values were according to the predetermined clinical significance for systolic and diastolic BP. Statistical significance was defined as a p value of less than 0.05 for all tests. Two-hundred ninety-nine (299) patients participated in the study, with a mean (SD) age of 44.2 years ± 15.1. Majority of the hypertensive subjects were on medications. There were 45 (15%) participants with aBP in the hypertensive level (BP > 140 mm Hg and diastolic BP > of 90 mm Hg). The median systolic wBP was 127 mmHg (range, 115-138) while aBP was 129 mmHg (range, 116-140). The median diastolic wBP and aBP were 80 mmHg (range, 74-88) and 82 mmHg (range, 75-88), respectively. A statistically significant correlation (p = 0.002 and p = 0.003) was obtained between the systolic and diastolic measurements using wBP and aBP apps. However, diastolic wBP was systematically lower by 10 mmHg. In conclusion, there is a correlation between the systolic and diastolic BP values taken through a validated digital wrist BP monitor and a validated aBP monitor. However, caution must be observed when interpreting the diastolic BP results. Clinical correlation is imperative.