Out-of-office blood pressure in children and adolescents: disparate findings by using home or ambulatory monitoring.

BACKGROUND: The validity of home blood pressure (HBP) measurements in children has not been evaluated, although in clinical practice such measurements are being used. This study compares HBP, with clinic (CBP) and daytime ambulatory blood pressure (ABP) in children and adolescents. METHODS: Fifty-five children and adolescents aged 6 to 18 years were evaluated with CBP (three visits), HBP (6 days), and daytime ABP. Mean age was 12.3 +/- 2.9 (SD) years, 33 boys. According to the Task Force CBP criteria, 26 were hypertensives, 6 had high-normal BP (hypertensive group), and 23 were normotensives (normotensive group). RESULTS: In the hypertensive group, CBP was 130.8 +/- 7.6/72.5 +/- 8.1 mm Hg (systolic/diastolic), HBP 118.9 +/- 6.3/73.7 +/- 6.7, and ABP 130.8 +/- 8.1/75.5 +/- 8.3. In the normotensive group, CBP was 112.8 +/- 8/63.1 +/- 6.3, HBP 106.7 +/- 8.4/67.2 +/- 5.2, and ABP 123.9 +/- 7.2/72 +/- 4.3. Strong correlations (P < .001) were observed between CBP-HBP (r = 0.73/0.57, systolic/diastolic), CBP-ABP (r = 0.59/0.49), and HBP-ABP (r = 0.72/0.66). In normotensive subjects, ABP was higher than both CBP and HBP for systolic and diastolic BP (P < .001). Furthermore, systolic HBP was lower than CBP (P < .01), whereas the opposite was true for diastolic BP (P < .05). In hypertensive subjects systolic HBP was lower than both CBP and ABP (P < .001), whereas CBP did not differ from ABP. For diastolic BP no differences were found among measurement methods. CONCLUSIONS: These data suggest that, in contrast to adults in whom HBP is close to the levels of daytime ABP, in children and adolescents HBP appears to be significantly lower than daytime ABP. Until more data become available, caution is needed in the interpretation of HBP in children and adolescents.

Reproducibility of home, ambulatory, and clinic blood pressure: implications for the design of trials for the assessment of antihypertensive drug efficacy.

BACKGROUND: The aims of this study were to compare the reproducibility of blood pressure (BP) measured in the clinic (CBP), at home (HBP), and by ambulatory monitoring (ABP), and to assess its implications on the accuracy of antihypertensive drug trials. METHODS: A total of 133 untreated subjects with elevated CBP were assessed with repeated measurements of CBP (five visits within 3 months), HBP (6 workdays within 2 weeks), and ABP (twice, 2 weeks apart). The reproducibility of CBP (one visit), HBP (2 days), and ABP (24 h) was quantified using the SD of differences (SDD) between repeated measurements. The number of subjects required in a comparative trial of two drugs was calculated for each measurement method. RESULTS: We found that HBP provided the lowest SDD values (6.9/4.7 mm Hg, systolic/diastolic, compared with 8.3/5.6 for ABP and 11.0/6.6 for CBP). For a parallel trial aiming to detect a difference in the effect of two drugs of 10 mm Hg systolic BP, 51 subjects would be required when using CBP compared with 29 using ABP and 20 using HBP (73, 53 and 37 subjects, respectively, for the detection of a 5 mm Hg difference in diastolic BP). CONCLUSIONS: The study shows that HBP seems to have superior reproducibility compared with both CBP and ABP. In addition, HBP can improve the accuracy of antihypertensive drug trials, thereby reducing the sample size required.