The blood pressure centiles presented here are based on data collected using a consistent and rigorous method in representative samples of nearly 23
000 children and young people living in Great Britain. As such, we believe they are the most accurate characterisation of normal blood pressure in any country to date.
It is well recognised that children's blood pressure tends to “track” over time.10,11,12,13,14
Moreover, high blood pressure in children is associated with the development of atherosclerosis,15,16,17,18,19
especially in those with additional risk factors, notably obesity.16,17,18,19,20
The charts will aid the timely recognition and monitoring of individuals with high blood pressure and hypertension, and facilitate the detection of children with secondary hypertension, consequent on renal, endocrine or other disease.1
Blood pressure monitoring is also important in children at risk of hypertension and/or vascular disease, such as those with obesity, diabetes, renal disease, or those receiving steroids or stimulant drugs and where a family history of hypertension is present.
We have used a standard nine‐centile format consistent with other charts in use in the UK.7
The charts show a progressive rise in systolic and diastolic pressure with increasing age, the rise being more marked in males during puberty. This is consistent with an effect of body size (indicated by weight) and obesity (weight adjusted for height) on blood pressure, the effect being stronger for systolic blood pressure. Thus males, who gain more weight at puberty than females, have significantly higher blood pressures, with almost a quarter satisfying the British Hypertension Society definition of hypertension,9
defined as systolic pressure >140 mm Hg and/or diastolic pressure>90 mm Hg, by the age of 24 years. The high systolic pressures in older teenagers and young adults, particularly men, are of special concern. However, blood pressure measurements on a single occasion are insufficient for the determination of high or high‐normal blood pressure for age,21,22
in the absence of evidence of a pathological cause or end organ damage, especially in children, who are more prone to “white coat” hypertension.23
Repeated measurements typically show that the majority of children with increased blood pressure on a single occasion subsequently have normal blood pressure.24
and mean arterial pressure27
have been found to be significant determinants of morbidity and mortality in adults. The significance of these measures in children is unknown, but pulse pressure may be an indicator of early arterial disease, as has been found in young adults with type 1 diabetes.27
Of note, we found that pulse pressure peaks at the end of puberty in both sexes, before falling in young adult life (fig 4) in contrast with systolic, diastolic and mean arterial pressures, which rise progressively with age (figs 1–3). A knowledge of normal ranges for pulse pressure and mean arterial pressure should aid research in this area.
The use of oscillometric blood pressure measurements was dictated by the nature of the health and social surveys, which required a reliable, reproducible and accurate method for determining blood pressure, using multiple observers.3,4
The Dinamap 8100 was subject to a rigorous calibration study3
to ensure its validity (although the calibration study did not include participants aged <16 years). However, the Dinamap monitor has been compared with direct radial artery pressure and central aortic pressure measurements in infants and children and was found to be superior to the auscultatory method.28,29
Moreover, particularly in young children, the conventional mercury sphygmomanometer can be difficult to use,4,20
with the Korotkoff sounds hard to distinguish, so, increasingly, automated oscillometric devices are being used in clinical practice.30
O'Brien et al
using the British Hypertension Society protocol, graded the Dinamap 8100 B for systolic blood pressure and D for diastolic blood pressure compared with the conventional mercury sphygmomanometer in adults.32
Paediatric studies have generally found significant differences, particularly between diastolic pressure assessed by fourth‐phase Korotkoff sounds.33,34,35
However, an Australian study of prepubertal children with type 1 diabetes using the British Hypertension Society protocol graded the Dinamap B for both systolic and diastolic pressure.36
The Dinamap 8100 and other oscillometric devices produce results that differ in comparison with the mercury sphygmomanometer. These differences have been attributed to inaccuracies37
but simply reflect the fact that different methods yield different results.1,38
However, in view of these differences, blood pressure results recorded with the mercury sphygmomanometer should be referenced to these centiles with caution.
The definition of hypertension in children is problematic. Use of the British Hypertension Society cut‐offs in adults is justified by adverse health outcomes in association with hypertension.9
However, no single cut‐off can define hypertension in children owing to the normal rise in blood pressure with age, and the paucity of evidence about what constitutes hypertension in children.1
Consequently, we suggest that, in children, those above the 98th centile on repeated occasions are stated to have high blood pressure for age, whereas those lying between the 91st and 98th centiles are stated to have high‐normal blood pressure for age. These cut‐offs are similar to recommendations made in the Taskforce Report on High Blood Pressure in Children and Adolescents in the USA.39
Our centile‐based definitions predict a prevalence of 2.3% for high blood pressure (>2 SDS) and 6.9% for high‐normal blood pressure (>1.33 SDS). These centiles should facilitate ongoing research into the importance of high or high‐normal blood pressure in children, and serve as a basis for defining hypertension in childhood.
The strong association between high blood pressure and weight/obesity that we and others have found40,41
is of particular concern given the well documented rise in childhood obesity.42
Childhood obesity, and its health consequences—including hypertension, metabolic syndrome and type 2 diabetes—present a major challenge for the coming years and demand vigilance and concerted action from all healthcare professionals to mitigate the adverse health consequences for children and young people.
What is already known on this topic
- Blood pressure rises through childhood and childhood blood pressure strongly predicts adult blood pressure.
- This rise in blood pressure is substantially determined by weight.
- As with growth, blood pressure is an important parameter of child health.
- Furthermore, atherosclerosis and hypertension may have their origins in childhood, particularly in those with additional risk factors—for example, obesity, renal disease or diabetes.
What this study adds
- These blood pressure centiles compiled from nationally representative data are the most comprehensive attempt to characterise normal blood pressure in childhood in Great Britain.
- The centiles complement existing charts for height, weight and body mass index and other parameters in evaluating the health of children.
- This information will contribute to a better understanding of blood pressure in childhood and aid further research.