Accuracy Assessment of a Wrist-Worn Oscillometric Blood Pressure Device Applied to the Upper Arm in Children

Background Accurate blood pressure (BP) measurement in children is essential for detecting pediatric hypertension, yet validation evidence for wrist-worn oscillometric devices in this population is sparse. The nonstandard application of a wrist BP device to the upper arm, a clinically plausible scenario when cuff size is compatible with a child's arm circumference, has not been previously evaluated. This study aimed to evaluate the accuracy and validation of a wrist-worn oscillometric BP device applied to the upper arm in children aged 3-8.5 years using brachial auscultatory mercury sphygmomanometry as the reference standard. Methodology This prospective, cross-sectional validation study enrolled 100 children (58 males; mean age = 4.9 ± 1.5 years) in a tertiary care hospital. A wrist-worn oscillometric device was applied to the upper arm and compared with brachial auscultatory mercury sphygmomanometry using the International Organization for Standardization (ISO) 81060-2:2018. A same-arm sequential protocol was used, yielding 300 paired comparisons. Accuracy was assessed using ISO Criteria 1 and 2, the British Hypertension Society (BHS) grading, and Bland-Altman analysis. Additionally, proportional bias regression and subgroup analyses were performed. Results The device met both ISO criteria for systolic BP (SBP; mean error = -4.62 ± 6.02 mmHg) and diastolic BP (DBP; -2.70 ± 5.19 mmHg). BHS grading was Grade A for DBP and Grade B for SBP. Bland-Altman 95% limits of agreement were -16.41 to +7.17 mmHg (SBP) and -12.88 to +7.48 mmHg (DBP). Significant proportional bias was observed for SBP (r = 0.370, p < 0.001) and DBP (r = 0.153, p = 0.008) with increasing underestimation at higher BP values. No sex differences were identified; a statistically significant but small age group difference was observed for DBP only. Conclusions This wrist-worn device applied to the upper arm met ISO validation requirements in 3-8.5-year-old children, and achieved BHS Grade A for DBP and Grade B for SBP. This device may be used as a screening tool in children of the tested age range, with confirmatory brachial auscultation recommended for elevated readings. The predominantly normotensive BP distribution in this cohort limits generalization of performance to hypertensive pediatric populations. Future studies should confirm our findings, recruit broader BP distributions, assess diverse anthropometrics, evaluate movement sensitivity, and explore pediatric-specific algorithms to reduce SBP proportional bias.