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The study by Jackson et al1 attempts to fill a gap in our knowledge in a very important area. Paediatricians in the United Kingdom have traditionally not included a blood pressure measurement as part of routine clinical assessment, as hypertension is not generally considered to be a common paediatric problem. Those who did check blood pressure had to rely on normal values derived from European and North American studies. The provision of blood pressures centiles for Great Britain is therefore a big step in the right direction and this is warmly welcomed. The data have been pooled from large representative samples and the methodology appears to be robust. The authors have chosen the well tested traditional nine-centile system, which all British health professionals are familiar with. However, a number of issues should be raised.
Firstly, the observed blood pressure appears to be remarkably high in a significant proportion of the paediatric population. This is most obvious in the pubertal boys, nearly quarter of whom would be labelled as hypertensive according to the definition suggested by the British Hypertension Society (BHS). In fact, the BHS classification of blood pressure level states that the optimal blood pressure for adults is a value of <120 mm Hg systolic and <80 mm Hg diastolic. Although <130mm Hg and <85mm Hg may be accepted as normal, any value above 130/85mm Hg is at least high normal if not hypertensive.2 This is not concordant with the international definition of high blood pressure as suggested by World Health Organization and International Society of Hypertension. In our own cardiology practice we struggle to see such high blood pressure values even in patients with coarctation of the aorta who have undergone surgery! Moreover, if the author’s suggested definition of hypertension (blood pressure above the 98th centile) is applied, many children currently labelled as hypertensive would fall into the category of high normal/normal blood pressure. For any clinician this is a challenging conundrum. One has to ask if it is wise to label these children as normotensive when clearly a few years down the line they may be classified as hypertensive by our adult physician colleagues. Does accepting this new definition of hypertension inevitably mean that we are choosing to ignore an opportunity to identify and influence an important risk factor for future coronary heart disease? There is a growing body of evidence to suggest that risk factors for coronary artery disease may be present in fetal life. Tireless efforts by professional bodies to prevent risk factors for ischaemic heart disease have encouraged attempts to achieve even lower blood pressure values in adults. Consequently, adopting higher normal blood pressure values in adolescence is going to be difficult to justify and is likely to lead to confusion, let alone a reduction in future risk of coronary artery disease.
Secondly, the BHS guidelines for the management of hypertension recommend that younger patients (aged <20 years) should not be presumed to have essential hypertension and should be investigated for an underlying cause. In the light of the current dataset, this would mean that a quarter of British pubertal males need investigation for an underlying problem, and if they are not investigated, are we choosing to ignore a potential renal/reno-vascular condition?
Thirdly, by adopting a new centile system for defining normal and high blood pressure we are choosing to differ from both our American and European counterparts. This is at a time when there is universal agreement on the definition of hypertension in adults. The blood pressure centiles in the North American population are based on more recent data (1999–2000 National Health and Nutrition Examination Survey) and in view of the ongoing obesity epidemic, a much lower cut-off value for defining hypertension was recommended.3 It was also suggested that high normal blood pressure, which is an indication for lifestyle changes, should be relabelled as prehypertension in order to promote preventive measures such as healthy diet and activity. Admittedly these centiles are somewhat labour intensive and time consuming to use in routine clinical practice. In fact, for the busy clinician the formula suggested by Somu et al4 may prove to be an easier and quicker tool to identify children with hypertension while remaining within accepted norms.
Incorporating the new British blood pressure centiles into clinical practice effectively translates into ignoring a substantial number of children who would otherwise be a target for lifestyle and perhaps medical interventions. This is contrary to the recommendations made by British Hypertension Society and endorsed by National Institute for Health and Clinical Excellence.5 We do not therefore feel comfortable in adopting the new blood pressure centiles or definitions of normal and high blood pressure values in children. We call for an open debate regarding the right way forward.
Competing interests: None declared.
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