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Hypertension in the young: a therapeutic perspective?

Birkenhäger, Willem H

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Erasmus University (emeritus) Rotterdam, The Netherlands, Rotterdam, The Netherlands.

See original paper on page 633

Correspondence and requests for reprints to Professor Willem H. Birkenhäger, Erasmus University (emeritus) Rotterdam, The Netherlands, Karl Marxstraat 35, 3076 DP Rotterdam, The Netherlands. Fax: +31 10 4325 790; e-mail: w.birkenhager@chello.nl

Blood pressure in children and adolescents, similar to adults, is distributed along a Gaussian-like pattern skewing towards the right, without any discriminate feature between ‘normal’ and ‘high'. Hence, high blood pressure merely means a quantitative deviation from a conventionally established statistical norm. Particular to this early age range, the norm and its conceived borderline with hypertension shift upward pari passu with growing up (age, length), exhibiting a spurt in the face of puberty. Gender represents an additional interactive term in this regard. Any value above the conventional 95th centile of the relevant fraction of the population is regarded as hypertension, with graded severities [1].

The phenomenon of ‘tracking’ (i.e. a blood pressure course following a predictable path along its originally established percentile plot in proportion to the over-all blood pressure trend) has remained a focus of interest in the long-term watch of blood pressure and care during childhood and adolescence [1]. Such trends tend to coalesce with additional risk facets, such as obesity and hypertension in parents and siblings. However, it should be noted that the predictive value of tracking is rather limited in a substantial proportion of these young subjects. This is due to such aspects as their enhanced responsiveness to varying ambient conditions and may lead to some measure of misclassification.

Overall, ‘significant’ hypertension is a rather extraordinary phenomenon in this age-range and more often than not signals an underlying disorder. The gamut of potential secondary hypertensions is wide and pluriform but, statistically, most of the causal mechanisms relate to renal substrates and their functional disorders: reflux nephropathy, cystic diseases, coarctation of the aorta or segmental renal artery stenosis and chronic glomerulonephritis. Following a correct diagnosis, such serious ailments tend to create a cumbersome therapeutic situation involving multidisciplinary efforts, amongst which antihypertensive treatment often tends to be put on the backburner. The role of blood pressure-lowering drugs has only occasionally been assessed in a methodological fashion [2].

In this issue of the journal, two allied groups of clinical investigators (from Berne and Milan) present an interesting view of the results of practical antihypertensive management of hypertensive children [3]. The authors undertook an analysis of the records on 80 hypertensive subjects (median age 10 years) who were under treatment by other colleagues; the latter were purposefully kept unaware of the authors’ evaluation of the records to avoid any interference. All patients had systolic and/or diastolic blood pressures above the 95th centile corresponding to their age, body height and gender. A majority of 73 had proven renal ailments (10 with transplanted kidneys); seven were considered to have essential hypertension.

All were subsequently treated by their (unwitting) physicians with stable antihypertensive drug regimens, in addition to other nephrologically orientated drugs, without any interference by the authors.

The treatment with various (unspecified) antihypertensive drugs (or combinations) resulted in satifactory blood pressure control (i.e. below the 95th borderline centile) in no less than three-quarters (60) of the total group, irrespective of the numbers or dosages of drugs taken. To any outsider, this seems to amount to a fairly favourable achievement, in comparison to the usual one-quarter effectiveness reported in adult populations worldwide [4,5].

Rather surprisingly, the authors saw fit to express a rather stern measure of dissatisfaction with the results they reported, even though they recognized the particular handicap in successfully treating patients with hypertension and malfunctioning kidneys.

Some comments may be called for in this regard. Although the authors’ quest for perfection may basically be commendable, one should not lose sight of the delicate balance between the overall (quality of) life prospects in these severely handicapped young patients, on the one hand, and the search for a semantically optimal target below the 95th centile on the other, the prognostic significance of which is still unproven. Looking at the therapeutic regimens employed according to the reported charts, one can hardly agree with the authors’ perception that accumulations up to seven drugs and 11 daily dosages reflect ‘clinical inertia', as the authors choose to phrase it.

That is, unless the real (underlying) clinical inertia resides in an (unreported) lack of proper diagnostic care and therapeutic surveillance. In this regard, some background information on whether these children really need dosage schedules of up to six antihypertensive doses pro diem would be required. One or several of the following leads might well have resulted in a minimilization of the drug burden: (i) a search for the apparently dominant individual hypertensive mechanism (renin–angiotensin–aldosterone system, lack of volume control, cyclosporin?); (ii) elimination of white-coat effects through ambulatory blood pressure monitoring [6]; and (iii) electronic surveillance of compliance with tablet consumption, the relevance of which has been demonstrated by the Lausanne Group [7]; these authors partly dismantled the notion of ‘resistant hypertension', showing that some half of such patients had failed to take their prescribed dosage. Of course such explorations constitute a temporary burden for pediatric patients but, in the long term, they may well result in a more tolerable regimen with even better results than those reported above.

It should be stressed that such considerations merely relate to the authors’ perception of ‘clinical inertia', and are not intended to detract from the intrinsic value of their pioneering initiative. It is hoped that the authors find themselves in a position to follow-up the fare of this unique cohort of hypertensive children.

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References

1.National High Blood Pressure Education Program Working Group on Hypertension Control in Children and Adolescents. Update on the 1987 Task Force Report. Pediatrics 1996; 98:649–658.
2.Sinaiko AR. Treatment of hypertension in children. Pediatr Nephrol 1994; 8:603–609.
3.Sieber US, von Vigier RO, Sforzini C, Fossali E, Edefont A, Bianchetti MG. How good is blood pressure control among treated hypertensive children and adolescents? J Hypertens 2003; 21:623–627.
4.Mancia G, Sega R, Milesi C, Cesana G, Zanchetti A. Blood-pressure control in the hypertensive population. Lancet 1997; 349:454–457.
5.Berlowitz DR, Ash AS, Hickey EC, Friedman RH, Glickman M, Kader B, Moskowitz MA. Inadequate management of blood pressure in a hypertensive population. N Engl J Med 1998; 339:1957–1963.
6.Sorof JM, Portman RJ. White coat hypertension in children with elevated casual blood pressure. J Pediatr 2000; 137:493–497.
7.Burnier M, Schneider MP, Chiolero A, Fallab Stubi CL, Brunner HR. Electronic compliance monitoring in resitant hypertension: the basis for rational therapeutic decisions. J Hypertens 2001; 19:335–341.
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