Current evidence is insufficient to assess the balance of benefits and harms of screening for high blood pressure in children and adolescents, the U.S. Preventive Services Task Force reported in JAMA.
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However, two experts in this area suggested there is evidence if you know where to look, and pediatric BP testing is crucial now.
In this update to the 2013 statement, the USPSTF’s systematic review focused on evidence surrounding the benefits of screening, test accuracy, treatment effectiveness and harms, and links between hypertension and cardiovascular disease (CVD) markers in childhood and adulthood.
Limited information was available on the accuracy of screening tests. No studies were found that directly evaluated screening for pediatric high BP or reported effectiveness in delayed onset or risk reduction for cardiovascular outcomes related to hypertension. Additionally, no studies were found that addressed screening for secondary hypertension in asymptomatic pediatric patients. No studies were found that evaluated the treatment of primary childhood hypertension and BP reduction or other outcomes in adulthood. The panel also was unable to identify any studies that reported on harms of screening and treatment.
When the adult framework for cardiovascular risk reduction is extended in pediatric patients, there are methodological challenges that make it harder to determine how much of the potential burden can actually be prevented, the panel said. The clinical and epidemiologic significance of percentile thresholds that are used to determine their ties to adult CVD has limited supporting evidence. Inconsistent performance characteristics of current diagnostic methods, of which there are few, tend to yield unfavorable high false-positive rates. Such false positives are potentially harmful, because they lead to “unnecessary secondary evaluations or treatments.” Because pharmacologic management of pediatric hypertension is continued for a much longer period, it is the increased likelihood of adverse events that should be cause for concern.
Should the focus for screening be shifted to significant risk factors?
In an accompanying editorial, Joseph T. Flynn, MD, MS, of Seattle Children’s Hospital, said that the outcome of the latest statement is expected, “given how the key questions were framed and the analysis performed.” To begin, he suggested restating the question: “What is the best approach to assess whether childhood BP measurement is associated with adult CVD or whether treatment of high BP in childhood is associated with reducing the burden of adult CVD?” The answer is to tackle these questions with randomized clinical trials that compare screening to no screening and treatment to no treatment. But such studies are likely infeasible, partly because of the required length of follow-up of 5-6 decades.
Perhaps a better question would be: “Does BP measurement in childhood identify children and adolescents who already have markers of CVD or who are at risk of developing them as adults?” Were these youth to be identified, they would become candidates for approaches that seek to prevent disease progression. Reframing the question in this manner better positions physicians to focus on prevention and sidestep “the requirement that the only acceptable outcome is prevention of CVD events in adulthood,” he explained.
The next step would be to identify data already available to address the reframed question. Cross-sectional studies could be used to make the association between BP levels and cardiovascular risk markers already present. For example, several publications from the multicenter Study of High Blood Pressure in Pediatrics: Adult Hypertension Onset in Youth (SHIP-AHOY), which enrolled roughly 400 youth, provided data that reinforce prior single-center studies that essentially proved there are adverse consequences for youth with high BP, and they “set the stage for the institution of measures designed to reverse target-organ damage and reduce cardiovascular risk in youth,” said Dr. Flynn.
More specifically, results from SHIP-AHOY “have demonstrated that increased left ventricular mass can be demonstrated at BP levels currently classified as normotensive and that abnormal left ventricular function can be seen at similar BP levels,” Dr. Flynn noted. In addition, “they have established a substantial association between an abnormal metabolic phenotype and several forms of target-organ damage associated with high BP.”