Within-visit blood pressure variability in children and adolescents in the National Health and Nutrition Examination Survey (2013-2020)

Background: Blood pressure (BP) varies depending on several factors. The objective of our study was to describe within-visit BP variability (BPV) in healthy children and compare BPV between manual and automated BP readings. Methods: We included individuals aged 8-17years with three BP readings from NHANES 2013-2020 cycles. From 2013 to 2016, BP was obtained using auscultation (manual protocol, MP) and, subsequently, using oscillometry (automated protocol, AP). We excluded individuals with DBP ‘zero’. Results: In 5656 individuals [MP group: 3365 (59.5%); AP group: 2291 (40.5%]), a DBP (difference between highest and lowest of three BP readings) at least 5mmHg was noted in 49.1 and 60.7% of individuals for SBP and DBP, respectively. DDBP at least 10mmHg was twice as common in the MP group as in the AP group. DDBP at least 20mmHg was observed in 4.4% individuals. A difference of at least 5mmHg between the initial and averaged second and third BP readings was noted in 24.9 and 34.5% of individuals for SBP and DBP, respectively. The highest of three BP readings was the first, second, or third in 44.2, 30.5, and 25.4% of individuals, for SBP, and 42.4, 29.8, and 27.7%, for DBP respectively. Conclusion: Less than half of individuals had three DBP readings within 5mmHg and some had DBP at least 20mmHg. Initial BP is not always the highest; inclusion of the second and third BP readings may be more representative of the individual’s actual BP. DBPV was higher with manual than with automated BP measurement.