Measurement of blood pressure in children.

Since that time, additional Task Force reports in 1987 2 and 1997 have established the currently used standards for blood pressure and defined hypertension in children according to gender, age, and height. Prior to the first Task Force report, blood pressure was measured infrequently in children. There was a general feeling that virtually all hypertension in children was secondary to some other disease process, ie, primarily renal, and most cases of hypertension, regardless of degree of blood pressure elevation, were aggressively evaluated and treated. As pediatricians began to measure blood pressure in their patients on a regular basis, it became clear that many cases of mild to moderate hypertension were not related to other diseases, and the diagnosis of essential hypertension began to creep into pediatric practice, particularly in the adolescent age group. There is little controversy about initiating antihypertensive therapy in patients with secondary forms of hypertension because of the usual chronicity of the problem and the documented beneficial effects to preservation of renal function. However, there is greater reluctance to begin treatment in a child with mild hypertension, without better scientific information about the natural history of blood pressure in the transition from childhood to adulthood and the long-term effects of the therapy. Thus, there is a need to ensure accuracy of blood pressure measurement to carefully select patients for evaluation and treatment. The prevalence of hypertension in children is low. Using the Task Force protocol, ie, measurement of blood pressure on multiple occasions to eliminate the accommodation effect of measurement and regression toward the mean, the prevalence of systolic and diastolic hypertension was 0.8% and 0.4%, respectively, after two separate measurements in a population of 14,686 African American and white 10–15 year olds. 4 Despite this low prevalence, the introduction of 24-h ambulatory blood pressure measurement (ABPM) to clinical practice has raised questions about the accuracy of auscultation in the diagnosis of hypertension and the relevance of white coat hypertension in the pediatric population. The paper by Sorof et al, in this issue of the Journal, 5 begins to answer some of these questions. It compares ABPM with casual blood pressures in a sample of 71 American children but relies on normative ABPM standards developed from data obtained in 1141 white European children. 6 Normative ABPM data on other cohorts also have been published. 7–9 However, all of these data sets are relatively small, raising questions about their applicability to general populations and other ethnic groups. Based on the Task Force experience, in which increasing the size of the population base from the first 1 to the second 2 Task Force report strengthened the standard blood pressure distributions and altered the levels of blood pressure used to define hypertension in children, emphasis hould be placed on obtaining ABPM blood pressure data from a considerably larger and more diverse population of normal children so as to establish reliable ABPM standards. A nagging issue limiting the incorporation of ABPM into pediatric practice has been lack of clear, carefully defined indications for its use. Sorof et al 5 make a valuable contribution to the pediatric ABPM literature by showing that the frequency of white coat hypertension is inversely related to the degree of hypertension, as determined from casual measurements. White coat hypertension was found in only 15% of patients with blood pressure 20% above normal levels, but was present in 52% of patients with blood pressure 10% above normal. They correctly conclude that ABPM does not add substantially to the accurate identification of children with moderate to severe hypertension. They also conclude that these data support the use of ABPM in children with mild hypertension, but the evidence for this is less convincing. Of the 71 patients in this study, 65% were males who were generally overweight (mean body mass index [BMI] 5 28.5 kg/m2) and older than the females; this is the expected demographic picture in pediatric population studies for children at the higher percentiles of blood pressure distribution. Most clinicians would be reluctant to initiate pharmacologic treatment in children with mild hypertension, particularly without first attempting non-pharmacologic intervention emphasizing weight loss and exercise. Even if white coat hypertension is identified in this group, studies confirming