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To the Editor:

The recent editorial by Samuels and Flynn[1] states that the recent evidence review for the US Preventive Services Task Force to provide evidence for their recommendations regarding screening children for hypertension to prevent cardiovascular disease[2] makes “flawed assumptions” and comes to “worrisome conclusions.” As lead author on the systematic review, I would like to respond to several inaccuracies and differences in interpretation that this editorial raises.

First, it is not clear why the authors considered that insufficient emphasis was given to evidence of association between elevated blood pressure and hypertension (or intermediate outcomes) in adults. Indeed, this was directly addressed by Key Question 3 in the review (“What is the association between hypertension in children/adolescents and hypertension and other intermediate outcomes in adults?”), which identified 10 longitudinal studies (including those cited by Samuels and Flynn). However, these showed a less clear-cut association than suggested by Samuels and Flynn. Indeed, we found that the probability of adult hypertension given the presence of elevated blood pressure (BP) or hypertension in childhood ranged from 19% to 65%. Samuels also appears to offer a different interpretation of two of the major studies (included in the review), which showed somewhat conflicting evidence of an association between adolescent systolic BP and carotid intimal-medial thickness in adults,[3, 4] and the presence of an association between child hypertension and adult microalbuminuria in black but not white adults in one study.[5] Since Samuels and Flynn did not highlight any additional evidence that we may have missed, their interpretation of this conflicting evidence is somewhat surprising.

Secondly, while I would agree with the authors that modern BP devices are easy to use in healthcare settings (or even at home with self-monitoring), I was surprised that they overlooked the paucity of evidence on diagnostic accuracy of these devices and the high false-positive results that will occur with screening. The evidence review found only two studies that had assessed the accuracy of BP devices in children/adolescents. Assuming a prevalence rate of hypertension of 5% and the accuracy of the best quality of the two accuracy studies,[6] we identified (sensitivity 65%, specificity 75%), this means that of 100 children who are screened, approximately 26 would screen positive, of whom only 3 would have hypertension. While I agree that measuring BP is relatively quick and easy, I am surprised that Samuels and Flynn dismiss the additional burden of repeat visits and costs this will incur for the majority of children who are suspected of having hypertension who don't actually have the condition.

Thirdly, the authors appeared to overlook the concerning lack of long-term data on efficacy and effectiveness of antihypertensive therapy in children. The review found that most trials of antihypertensive drugs lasted only a few weeks and showed variable effects on systolic and/or diastolic BPs (and many ignored the phenomenon of regression to the mean). Most parents and clinicians embarking on therapy that lasts decades should surely expect a more robust body of evidence than this? Rather, they cite two studies, both of which were small uncontrolled cohort studies involving 44[7] and 86 adolescents[8] that showed variable effects on intermediate cardiovascular endpoints with various types of antihypertensive treatments. Such sparse and low-quality evidence is not particularly convincing for most parents and pediatricians embarking on therapy of potentially large numbers of children and adolescents for multiple decades.

The crux of the editorial is that the review should not have even attempted to search for direct evidence for the effect of screening for hypertension in children and adolescents on cardiovascular outcomes in adults. The authors point out the obvious difficulties in following up cohorts of screened and unscreened children and adolescents for sufficient time to determine impact on cardiovascular clinical outcomes. This is precisely why our review looked for evidence of the effectiveness of screening on more proximal (intermediate) outcomes, which are laid out clearly in the analytic framework. Therefore, we searched for the effect of screening children and adolescents not only on adult cardiovascular disease, but also on intermediate cardiovascular outcomes, which are more frequent and occur sooner than clinical sequelae. Unfortunately, the evidence was mostly sparse and unconvincing.

Finally, while I agree that the state of evidence in pediatric hypertension is “early,” I profoundly disagree with their assertion that attempting to objectively assess the current state of evidence for the US Preventive Services Task Force is “premature.” As our review indicates, there are numerous important research gaps, many of which can be addressed with existing datasets or with feasible study designs that could drastically improve the state of the evidence. The bottom line is that clinicians, parents, and children/young people deserve to know the following: (1) Can we detect high BP accurately? (2) Is the treatment effective and safe? And (3) How important is it in the long term for cardiovascular health?

Perhaps now is the time to work across the primary care–specialty care divide to further refine the major research gaps and design strategies to address them in a rational way.

References

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  • 1
    Samuels JA, Bell C, Flynn JT. Screening children for high blood pressure: where the US Preventive Services Task Force went wrong. J Clin Hypertens (Greenwich). 2013;15:526527.
  • 2
    Thompson M, Dana T, Bougatsos C, et al. Screening for hypertension in children and adolescents to prevent cardiovascular disease. Pediatrics. 2013;131:490525.
  • 3
    Li S, Chen W, Srinivasan SR, et al. Childhood cardiovascular risk factors and carotid vascular changes in adulthood. JAMA. 2003;290:22712276.
  • 4
    Raitakari OT, Juonala M, Kahonen M, et al. Cardiovascular risk factors in childhood and carotid artery intima-media thickness in adulthood: the Cardiovascular Risk in Young Finns Study. JAMA. 2003;290:22772283.
  • 5
    Hoq S, Chen W, Srinivasan SR, Berenson GS. Childhood blood pressure predicts adult microalbuminuria in African Americans, but not in whites: the Bogalusa Heart Study. Am J Hypertens. 2002;15:1036.
  • 6
    Stergiou GS, Nasothimiou E, Giovas P, et al. Diagnosis of hypertension in children and adolescents based on home versus ambulatory blood pressure monitoring. J Hypertens. 2008;26(8):15561562.
  • 7
    Kupferman JC, Paterno K, Mahgerefteh J, et al. Improvement of left ventricular mass with antihypertensive therapy in children with hypertension. Pediatr Nephrol. 2010;25:15131518.
  • 8
    Litwin M, Niemirska A, Sladowska-Kozlowska J, et al. Regression of target organ damage in children and adolescents with primary hypertension. Pediatr Nephrol. 2010;25:2482499.