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    Easier pediatric blood pressure screening

    Dr. Andrew Schuman recently sat down with Dr. David Kaelber to discuss the implications of his vastly simplified screening tool for pediatric hypertension

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    Q: How was the simplified table developed? What are its advantages and limitations?

    a: Height was eliminated by using the values for children and adolescents at the 5th height percentile (lowest height percentile in the tables in the Fourth Report). In other words, we assume all children and adolescents are at the 5th percentile for height. The advantages of this approach include 1) creating a simplified table that does not rely on height and 2) creating a table that is 100% sensitive for detecting abnormal BP. The potential limitation is a high false positive rate in that children and adolescents who are above the 5th percentile for height may have normal BP, but the simplified table may identify their BP as abnormal.

    As discussed in our paper,3 we do not see this as a significant issue, since the precision of BP measurements is relatively low and can vary up to 10 to 15 mmHg for systolic, and 5 to 10 mmHg for diastolic BPs based on factors such as time of day, automatic versus manual BP measurement, office versus ambulatory readings, and who is doing the manual measurement. This variation in precision is equal to or greater than the difference in cut-off BP values for the 5th height percentile and the 95th height percentile, which vary between 6 to 9 mmHg for systolic BPs and 3 to 5 mmHg for diastolic BPs.

    Q: A height-independent BP table makes it much easier to interpret BP readings obtained at well visits. Given its ease of use and the importance of detecting children with elevated BPs, would you encourage pediatricians to check BP at ill-child visits?

    a: The Fourth Report recommends that BP screening be performed in all children >3 years old who are seen in medical settings.2 I agree with these recommendations, although recognize that in acute illness, elevated BPs may be more likely the result of the acute illness as opposed to chronic hypertension or chronic prehypertension.

    Q: The Fourth Report goes into some detail regarding the evaluation of elevated BPs in children, and presents two categories of pediatric hypertension. What is the difference between Stage I and Stage II hypertension, and why is it important?

    a: Stage 1 pediatric hypertension is BP between the 95% and 99% (+ 5 mmHg) for systolic and/or diastolic BP. Stage 2 pediatric hypertension is BP equal to or greater than the 99% (+ 5 mmHg) for systolic and/or diastolic BP.

    Once confirmed on repeated measures, stage 1 hypertension allows time for evaluation before initiating treatment unless the patient is symptomatic. Patients with stage 2 hypertension may need more prompt evaluation and pharmacologic therapy. Symptomatic patients with stage 2 hypertension require immediate treatment and consultation with experts in pediatric hypertension.2 In others words, the categorization is important because it helps stratify the significance and urgency of the problem, and helps to dictate what the next steps should be.

    Q: How many BP measurements should be obtained to confidently classify a child as normotensive, prehypertensive, or hypertensive?

    a: Per the Fourth Report, at least three BPs on different visits, at different dates/times are needed in the prehypertensive or hypertensive range for the patient to carry one of these diagnoses. From this description, it's unclear (and we had a letter to the editor in JAMA about this in January 2008) if the abnormal values need to be consecutive and how to categorize some combination of normal and abnormal BP values. For example, if the patient had six BP readings without any interventions as follows: visit 1: hypertensive BP, visit 2: normotensive BP, visit 3: hypertensive BP, visit 4: hypertensive BP, visit 5: normotensive BP, and visit 6: normotensive. Does this child have hypertension? According to the strict definition, yes.

    Personally, I would not say this person had chronic hypertension at the sixth visit because the two most recent BP values were normal without any intervention. Hopefully future guidelines will help clarify this. The equivalent guidelines for adults from the Seventh Report of the Joint National Committee on Hypertension in Adults use the criteria "the average of two or more properly measured, seated, BP readings on each of two or more office visits."4 In the absence of clearer pediatric BP guidelines, my own common sense, and experience diagnosing and managing hypertension in adults, I tend to follow this "average" value guideline in my pediatric patients.

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    Andrew J Schuman, MD, FAAP
    Dr Schuman, section editor for Peds v2.0, is clinical assistant professor of Pediatrics, Geisel School of Medicine at Dartmouth, ...

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