Journal of Human Hypertension (2011) 25, 218–223 & 2011 Macmillan Publishers Limited All rights reserved 0950-9240/11 www.nature.com/jhh
ORIGINAL ARTICLE
Comparison of office, ambulatory and home blood pressure in children and adolescents on the basis of normalcy tables GS Stergiou1, N Karpettas1, DB Panagiotakos2 and A Vazeou3 1
Hypertension Center, Third University Department of Medicine, Sotiria Hospital, Athens, Greece; Department of Nutrition—Dietetics, Harokopio University, Athens, Greece and 3First Department of Pediatrics, P & A Kyriakou Children’s Hospital, Athens, Greece
2
In children and adolescents, the diagnosis of hypertension is based on office, home and ambulatory blood pressure (BP) measurements. Different normalcy tables for each method have provided 95th percentiles of BP as thresholds for hypertension diagnosis. This study assessed the differences in BP thresholds among these methods when applied in the pediatric population. The most widely used office, home and ambulatory BP normalcy tables were compared in terms of the 50th and 95th percentiles by gender and age. The range of office BP change with increasing age is wider than for home or ambulatory BP in boys and girls, apart from systolic BP in boys. Percentiles of home BP are
consistently lower than that of daytime ambulatory BP. There is a trend for office BP to be lower than home or daytime ambulatory BP in the younger age subgroups. This difference is progressively eliminated with increasing age, apart from systolic BP in boys. In conclusion, in children and adolescents, the relationship between office, home and ambulatory BP thresholds provided by the widely used normalcy tables is not the same as in the adults. These findings should be taken into account when evaluating BP measurements in children and adolescents in clinical practice. Journal of Human Hypertension (2011) 25, 218–223; doi:10.1038/jhh.2010.59; published online 3 June 2010
Keywords: children; adolescents; office blood pressure; home blood pressure; ambulatory blood pressure; normalcy
tables
Introduction In children and adolescents, the thresholds for hypertension diagnosis are based on the 95th blood pressure (BP) percentiles for gender, age and height derived from large cross-sectional studies of normalpopulation samples.1,2 As in the adults, because of the phenomena of white coat and masked hypertension, office and out-of-office BP measurement (with ambulatory monitoring or at home) is needed for the precise diagnosis of hypertension in children.1–5 The recent guidelines by the European Society of Hypertension for the assessment of children and adolescents with elevated BP1 and by the American Heart Association for the use of ambulatory BP monitoring in children6 stated that this method is indispensable for the precise diagnosis of
Correspondence: Professor GS Stergiou, Third University Department of Medicine, Hypertension Center, Sotiria Hospital, 152 Mesogion Avenue, Athens 11527, Greece. E-mail:
[email protected] Received 22 February 2010; revised 15 April 2010; accepted 24 April 2010; published online 3 June 2010
hypertension in children. Home BP monitoring is also being used by practitioners for the assessment of out-of-office BP in children,7,8 yet evidence on its usefulness in the pediatric population has only recently been reported.9 For the assessment of BP levels in the office, at home and with ambulatory monitoring in children and adolescents and the diagnosis of white coat, masked and sustained hypertension in research and in clinical practice, normalcy tables derived from different studies are used.2,10–13 However, there are differences in office, home and daytime and nighttime ambulatory BP thresholds derived from each of these normalcy tables,2,10–13 which are mainly attributed to inherent differences between these BP measurement methods. Differences in the population samples included in the cross-sectional studies that defined these normalcy tables might have also contributed to the differences among the BP measurement methods. This paper compares the most widely used and recommended by current guidelines normalcy tables for office, ambulatory and home BP in children and adolescents, aiming to assess differences in the BP
Blood pressure normalcy in children GS Stergiou et al 219
Blood Pressure in Children and Adolescents.2 These tables provide BP percentiles per year of age according to the percentiles of height. To select BP percentiles for the same body size as in the normalcy tables for home BP, we used percentiles of height from the Centers for Disease Control and Prevention growth charts14 that correspond to the median height for each year of age from 7 to 17 years in the participants of the Arsakeion school database.13
thresholds of these measurement methods when applied in the evaluation of individual children and adolescents in clinical practice.
Methods Normalcy tables and curves for office, ambulatory and home BP in children and adolescents that are proposed for clinical use by American and European guidelines for pediatric hypertension were identified.1,2,6 For each BP measurement method (office, home and ambulatory), the 50th and 95th percentiles by age (per year from 7 to 16 years), separately for boys and girls and for systolic and diastolic BP were selected. Percentiles were obtained from the following normalcy tables: (a) Ambulatory BP: normalcy tables derived by the German study by Soergel et al.11,12 that have been endorsed by both European1 and American guidelines.2,6 The original report from this study provided ambulatory BP percentiles by height.11 In more recent papers, percentiles by age (5–16 years) have been also provided.6,12 Percentiles for the daytime and the nighttime period have been provided, defined as 0800 to 2000 hours and midnight to 0600 hours, respectively. Ambulatory BP recording frequency was at 15–20 min during the day and 30–50 min during the night.11 (b) Home BP: normalcy tables constructed from the Arsakeion school study by Stergiou et al. in Greece,13 which is the only study that provided normative data for home BP measurements in children and adolescents and has been endorsed by the recent European Guidelines.1 In the original paper, home BP percentiles have been provided for 10-cm height subgroups.13 For the purpose of this analysis, we developed new normalcy tables (50th and 95th percentiles) by age from the Arsakeion study database using the same population and methodology as in the original paper.13 (c) Office BP: normalcy tables included in the 4th Report of the National High Blood Pressure Education Program Working Group on High
This approach allowed the direct comparison of the office, home and ambulatory BP percentiles for boys and girls by age, as used when assessing individual children and adolescents in clinical practice.
Results Data sets and percentiles
A comparison of the participants’ characteristics and the BP measurement method used in the crosssectional studies that provided the normative data for office, ambulatory and home BP used in this analysis are presented in Table 1. The 50th and 95th percentiles of home BP by age developed from the Arsakeion school database13 for the purpose of this analysis are shown in Table 2. The 50th and 95th percentiles for office, home and daytime, nighttime and 24-h ambulatory BP derived from the corresponding normalcy tables for each year of age (from 7 to 17 years), separately for boys and girls and for systolic and diastolic BP, are presented in Figure 1.
Ambulatory BP
Data in Figure 1 suggest that daytime BP is by 4–7 mm Hg higher than 24-h BP and nighttime BP by 14–18 mm Hg lower than daytime BP. These differences are consistent in boys and girls assessed by height or age and also for the 50th and the 95th percentiles. There is a clear stepwise rise in systolic ambulatory BP levels with increasing age (from 7 to 16 years) of 14–20 mm Hg in boys and 7–9 mm Hg in girls. However, the corresponding changes in
Table 1 Characteristics of participants and measurement method in cross-sectional studies used to develop the normative tables for blood pressure measurements in the office, at home and with ambulatory monitoring in children and adolescents Blood pressure
Year published (reference)
Country
Office
20042
US
Ambulatory
199711,12
Home
200713
No. of subjects
Age (years)
Gender Male (%)
Female (%)
Measurement method (device)
No. of measurements
63 227
1–17
50.9
49.1
Auscultatory (mercury)
Single occasion
Germany
949
5–20
48.9
51.1
Oscillometric (SpaceLabs 90207)
Days 36–48, nights 7–9
Greece
778
6–18
46.0
54.0
Oscillometric (Omron 705 IT)
12
Journal of Human Hypertension
Blood pressure normalcy in children GS Stergiou et al 220
diastolic BP with increasing age are negligible (1–3 mm Hg in boys and girls). These findings are similar for the 50th and the 95th percentiles. Home BP
Home BP is lower than daytime ambulatory BP by 4–8 mm Hg for systolic and diastolic BP in boys and girls. These differences tend to be smaller regarding the 95th percentiles. The range of the home BP change with increasing age is similar as for ambulatory BP (for systolic BP, 15–21 mm Hg in boys and 6–11 mm Hg in girls and for diastolic BP, 1–4 mm Hg in boys and girls). Table 2 Percentiles for systolic/diastolic home blood pressure in children and adolescents by age (Arsakeion school study)
Age (years) 6 7 8 9 10 11 12 13 14 15 16 17
Percentiles for boys
Percentiles for girls
50th
95th
50th
95th
103/62 106/65 107/65 108/65 108/66 111/66 113/66 117/66 119/66 122/66 123/66 124/67
112/70 120/77 125/77 126/78 126/78 128/78 132/78 139/80 139/80 140/80 141/80 141/80
102/62 106/63 107/64 107/64 108/64 108/64 109/65 111/65 111/65 112/66 112/67 112/67
112/77 122/79 123/80 124/80 125/80 125/80 126/80 128/80 132/80 133/80 133/80 133/80
Office BP
The range of office BP change with increasing age (from 7 to 17 years) is 14–17/7–9 mm Hg for systolic/ diastolic BP for boys and girls, which is wider than for home or daytime ambulatory BP, apart from systolic BP in boys. There is a consistent trend for office BP to be lower than home or daytime ambulatory BP in the younger age subgroups. This difference seems to be progressively eliminated with increasing age, apart from systolic BP in boys. Boys versus girls
The comparative diastolic BP curves for 50th and 95th percentiles are very similar in boys and girls (Figure 1). However, for systolic BP again there seems to be no clear difference in the young children, whereas the yearly steps of upwards shift in the BP curves with increasing age were bigger in boys (Figure 1), which represent the higher BP levels in boys compared with girls during adolescence with all measurement methods.
Discussion This paper provides a comparison of office, home and ambulatory BP in children and adolescents on the basis of normalcy tables derived from large cross-sectional studies. The 50th percentiles were used to present the BP values at the midpoint of the normal range and the 95th percentiles to provide the BP thresholds for hypertension diagnosis. The main
GIRLS
BOYS 150
150
95th Percentiles
50th Percentiles
140
140 Systolic BP
130
Systolic BP
130
120
120
110
110 mmHg
mmHg
95th Percentiles
50th Percentiles
100 90
100 90
Diastolic BP
80
Diastolic BP
80
70
70 Age Categories (years) 14 17 13 12 16 11 15
60 50
10 9 8 7
Age Categories (years) 14 17 13 12 16 15 11
60 50
O
H
D
N 24h
O
H
D
N 24h
O
H
D
N 24h
O
H
D
10 9 8 7
N 24h
Figure 1 Comparison of 50th and 95th percentiles for office, ambulatory and home blood pressure in children and adolescents by age2,11–13. BP, blood pressure; O, office BP; H, home BP; D, daytime ambulatory BP; N, nighttime ambulatory BP; 24 h, 24-h ambulatory BP. Journal of Human Hypertension
Blood pressure normalcy in children GS Stergiou et al 221
conclusion from these comparisons is that in children and adolescents, the relationship between office, home and ambulatory BP thresholds provided by widely used normalcy tables is not the same as in the adults. Although this comparative assessment has the limitation that the reported office, home and ambulatory BP values have not been obtained in the same population but were derived from different studies, the BP thresholds compared are recommended by current guidelines to be used for decision making in individual children and adolescents in clinical practice.1,2 The normalcy tables for ambulatory BP used in this study have been developed by a study in Germany11,12 and have been endorsed by the US National High Blood Pressure Education Program Working Group on high blood pressure in children and adolescents,2 the American Heart Association Atherosclerosis, Hypertension and Obesity in Youth Committee of the Council on Cardiovascular Disease in the Young and the Council for High Blood Pressure Research6 and the recent European Society of Hypertension recommendations for the management of high BP in children and adolescents.1 The normalcy tables used for home BP are the only ones available derived from the Arsakeion school study in Greece13 and have been endorsed by the recent European Society of Hypertension recommendations for the management of high BP in children and adolescents.1 For office BP, the US normative data2 were preferred to the Man et al.10 normalcy graphs, which have been based on pooled data from six European countries (n ¼ 28 043). This choice was made because the US tables have been derived from a larger database (n ¼ 63 227), are the most widely used normalcy tables in clinical practice and are the recommended normalcy tables not only by the American2 but also the recent European guidelines for pediatric hypertension.1 Although the data sets used for the development of normalcy tables for office BP were much larger than those for home or ambulatory BP (Table 1), the two latter methods are known to have superior reproducibility15,16 to office/ clinic BP measurements reducing thereby the sample size required. The major limitation in comparing the percentiles of these normalcy tables is the fact that these have been derived by studies of different populations, yet this approach is recommended by current guidelines for the assessment of BP in individual children and adolescents in clinical practice. The rise in BP levels with increasing age in children and adolescents is well known. This analysis showed that home BP seems to have similar ability as ambulatory monitoring to reveal the change in BP levels with increasing age. This applies for systolic and diastolic BP, yet for the latter both methods revealed negligible changes with increasing age. Interestingly, the range of office BP levels across the age subgroups was considerably wider than for home or ambulatory BP measurements (more evident for diastolic BP). One explana-
tion is that the effect of the office environment and the observer on measured office BP is not the same in all children and adolescents, which results to the phenomena of white coat and the masked hypertension. These phenomena probably result in wider BP range of office than out-of-office measurements (home and ambulatory BP). On the other hand, it might be argued that in children, the oscillometric technique that was used to define the normal home and ambulatory BP range (11–13) might be less sensitive that the conventional auscultatory technique to reveal the diastolic BP changes with increasing age in children. Indeed, the SpaceLabs 90207 oscillometric ambulatory BP monitor that has been used in the study that defined the normal range of ambulatory BP11,12 has been validated in only one study in children and adolescents and was found accurate for systolic but not for diastolic BP measurement.17 However, the oscillometric BP monitor used in the Arsakeion school study that defined the normal range of home BP in children has been validated in a relative large study of children and adolescents (n ¼ 197) and found to fulfill the accuracy requirements of the European Society of Hypertension International Protocol for systolic and diastolic BP.18 The comparison of the two out-of-office BP measurement methods (home and ambulatory BP) is probably the most challenging finding of this analysis. In contrast to the findings in the adults in whom home BP levels are similar to daytime ambulatory BP,15 in children and adolescents, systolic and diastolic home BP seems to be significantly and consistently lower than daytime ambulatory BP by 4–8 mm Hg. This difference is largely unknown among physicians and is confirmed by the findings of a recent review of the few available prospective pediatric studies that involved both home and ambulatory BP monitoring.9 In the ESCAPE trial in 118 children and adolescents with chronic renal failure (78% on antihypertensive drug treatment), mean home BP was by 6.4 mm Hg lower than daytime ambulatory BP.19 Moreover, in a study in 102 untreated children and adolescents referred to a hypertension center for elevated BP (48% without hypertension), home BP was lower than daytime ambulatory BP by 10.6/3.3 mm Hg (systolic/ diastolic).20 Thus, both the normative tables derived from different subjects and also direct comparison trials in the same subjects suggest that in the pediatric population, home BP is significantly lower that daytime ambulatory BP, which is probably attributed to the high level of physical activity in the young population during the day. Another challenging issue is the changing relationship of office with home BP with increasing age (higher home than office BP in the younger children with progressive elimination of this difference with increasing age). No such phenomenon was observed when the two out-of-office BP measurements (home and ambulatory) were compared. The same pattern Journal of Human Hypertension
Blood pressure normalcy in children GS Stergiou et al 222
of changing office–home BP relationship with age was found in the Arsakeion school study,21 where both measurements have been obtained using the same (oscillometric) device, which excludes any influence due to different BP measurement technology (auscultatory for office BP versus oscillometric for home and ambulatory BP). A plausible explanation provided in the Arsakeion study paper21 is that children of different age are affected differently by the office environment. Thus, the white coat reaction, which is regarded as an ‘alarm’ or ‘defense’ reaction, might be more prominent in the adolescents resulting in higher office than out-of-office BP levels with increasing age. In conclusion, a thorough comparison of normalcy tables for office, home and ambulatory BP in children and adolescents currently recommended by current guidelines for clinical use, revealed differences in the relationship between the BP thresholds provided, as compared with the adults. These findings should be taken into account in the evaluation of office and out-of-office BP levels in children and adolescents in clinical practice. Further studies in large samples of children and adolescents providing direct comparisons of office and out-of-office BP measurements in the same subjects are needed. What is known about topic K As in the adults, in children and adolescents both office and out-of-office blood pressure measurements (home and ambulatory) are needed for the accurate diagnosis of hypertension. K Recent European guidelines recommend the use of normalcy tables for office, home and ambulatory blood pressure measurements obtained by different studies.
2
3
4 5
6
7 8
9 What this study adds K A comparison of the 50th and 95th percentiles of the most widely used and recommended by current guidelines normalcy tables shows that in children and adolescents, the relationship between office, home and ambulatory blood pressure thresholds is not the same as in the adults. K In children and adolescents, home blood pressure seems to be significantly and consistently lower than daytime ambulatory blood pressure, whereas in adults no such difference is found. Furthermore, there is a change in the relationship between office and home blood pressure with increasing age, with lower home values in the younger children and a progressive elimination of this difference in older children and in adolescents. K These findings should be taken in account in the evaluation of office and out-of-office blood pressure measurements in clinical practice.
Conflict of interest
10
11
12
13
The authors declare no conflict of interest. 14
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