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Arch Dis Child. 2007 November; 92(11): 1045–1046.
PMCID: PMC2083585

Blood pressure charts in UK children

The study by Jackson et al on blood pressure centiles for Great Britain1 provides us with valuable information and insight into children's blood pressure centiles measured on automated monitors. This is the first time we have been able to see normative data for such large numbers of children in the UK.

There are, however, a few things in this publication that we would like to discuss. It is generally accepted that blood pressure in children depends not only on sex and age but also on the height of the child. The correlation with height is physiologic and needs to be taken into consideration when evaluating the child. In, for example, 2‐year‐old girls with height between the 5th and 95th centile, this difference can be 7 mm Hg. Thus, we were surprised to see only a weak correlation with height and disappointed to see that the authors' extensive data were not integrated with height.

The correlation with weight, found by the authors, has more to do with the increasing and often pathologic blood pressure in obesity. We also wondered if this strong correlation was related to the size of the blood pressure cuff. The difference between a cuff that encircles 80% or 100% of the circumference of the arm can be significant, especially in obese children.

Secondly, we were surprised to see that the authors had redefined hypertension to be above the 98th centile compared to the commonly used 95th centile without any explanation. The definition of hypertension is clearly much more complex in children compared to in adults. Children, so far, lack long‐term prospective outcome data showing which blood pressure is optimal for each age and the definition is thus strictly statistical. We do not dispute that the 98th centile might well be a better definition than the 95th. However, the international agreement that is followed by most doctors treating children with hypertension refers to the 95th centile not the 98th.

Thirdly, the blood pressure values shown in the new graphs are clearly much higher than those commonly used,2 even if they are difficult to compare as different centiles are given. As an example, a 17‐year‐old boy of median height would be defined as hypertensive at 136 mm Hg in the old charts and at 143–144 mm Hg in the new. This is also a clinically very significant difference. One reason for this could be the well‐known difference between manual and automated blood pressure measurements.

We would strongly suggest that the authors use their important data to set reference levels outlining the 95th centile for age and height centiles in children. Such graphs would be invaluable in clinical practice particularly where automated machines are the only available option for monitoring blood pressure in children.

Footnotes

Competing interests: None declared.

References

1. Jackson L V, Thalange N K S, Cole T J. Blood pressure centiles for Great Britain. Arch Dis Child 2007. 92298–303.303 [PMC free article] [PubMed]
2. National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. Pediatrics 2004. 114(2 Suppl)555–576.576 [PubMed]

Articles from Archives of Disease in Childhood are provided here courtesy of BMJ Group