The prevalence of hypertension is increasing in children, and may persist into adulthood. This systematic review was conducted for the US Preventive Services Task Force recommendation on the effectiveness of screening asymptomatic children and adolescents for hypertension in order to prevent cardiovascular disease.
Eligible studies were identified from Medline and the Cochrane Library (through July 2012). We included trials and controlled observational studies in asymptomatic children and adolescents on the effectiveness and harms of screening and treatment, as well as accuracy of blood pressure measurement. One author extracted study characteristics and results, which were checked for accuracy by a second author.
No studies evaluated the effects of screening for hypertension on health outcomes. Two studies of screening tests for elevated blood pressure reported moderate sensitivities (0.65, 0.72) and specificities (0.75, 0.92). Sensitivities and specificities of child hypertension for the later presence of adult hypertension (7 studies) were wide ranging (0–0.63 and 0.77–1.0, respectively), and associations between child hypertension and carotid intima media thickening and proteinuria in young adults (3 studies) were inconsistent. Seven studies reported that drug interventions effectively lowered blood pressure in adolescents over short follow-up periods. No serious treatment-related adverse effects were reported.
There is no direct evidence that screening for hypertension in children and adolescents reduces adverse cardiovascular outcomes in adults. Additional studies are needed to improve diagnosis and risk stratification of children with elevated blood pressure and to quantify risks and benefits of interventions.
To the Editor: Thompson et al1 published a report on a review conducted for the US Preventive Services Task Force (USPSTF) on the effectiveness of screening asymptomatic children and adolescents for hypertension to prevent cardiovascular disease. The authors examined 8 key questions based on evidence from published studies and concluded "there is no direct evidence that screening for hypertension in children reduces adverse cardiovascular outcomes in adults."1 While the authors are to be commended for conducting a rigorous review, it is notable that 5 of their 8 questions have limited or no evidence and cannot be answered. The authors articulated gaps in acceptable evidence, and outlined areas for which research is needed. We have substantial concerns on how this report and recommendations of the USPSTF on blood pressure (BP) screening will be interpreted by primary care clinicians and stakeholders in child health. Measurement of BP beginning at age three years as part of routine pediatric health care has been recommended since 1977.2 Reduction of cardiovascular events in adults has never been a primary rationale for BP measurement in children. The purpose, rather, has been to identify asymptomatic secondary hypertension and to identify children with heightened risk for primary hypertension. When identified and appropriately managed, there are clear health benefits for children with secondary hypertension. Reduction in modifiable risk factors that contribute to hypertension are also generally accepted as beneficial to child health. We are concerned that the USPSTF statement will be interpreted by some health providers as a recommendation to stop measuring BP during routine health care visits.
Unlike adult hypertension, there are no hard outcome data that link a BP level in childhood with increased risk for future stroke, kidney failure, heart failure, or death. Because there are no outcome data, hypertension in childhood is defined statistically as the extreme of the normal BP distribution; thus the hypertension definition of BP >95th percentile. Clinical experience has shown this definition does detect children with primary hypertension. Left ventricular hypertrophy (LVH) is detectable in a substantial portion of children with confirmed hypertension. It has not been proven that hypertensive adolescents with LVH will develop premature cardiovascular events. However, from what is known about hypertension with LVH in adults, it is unlikely there will ever be an observational study to determine cardiovascular outcome; or a placebo-controlled trial to develop evidence that blood pressure reduction improves outcomes. Thus, some Key questions raised by the USPSTF. are currently unanswerable. There are several older prospective cohort studies that enrolled children and have data extending into adulthood. Collectively, those data may eventually provide some of the missing evidence on the currently unanswerable Key questions. We strongly embrace the need for further research as outlined by Thomson et al. and hopefully the resources will become available to make that happen. Regardless of how the USPSTF frames their recommendations, routine measurement of BP in childhood should not be abandoned.
Bonita Falkner, MD Incoming Chair of the International Pediatric Hypertension Association
References: 1. Thompson M, Tracy D, Bougatsos C, Blazina I and Norris SL. Screening for hypertension in children and adolescents to prevent cardiovascular disease. Pediatrics 2013; 131: 490-525 2. NHLBI Report of the Task Force on blood Pressure Control in children. Pediatrics 1977;59(Suppl):797-820.
The International Pediatric Hypertension Association (IPHA) is an organization that brings together a multispecialty, multidisciplinary group of health care providers and scientists committed to delineating the origins and manifestations of hypertension in children and improving the care of children and young adults affected by this condition. IPHA has established a three-fold mission to:1)Foster and maintain an open forum among pediatric hypertension healthcare professionals worldwide;2)Participate in research initiatives promoting improved treatment of the hypertensive patient;and 3) Educate healthcare professionals and the lay public about the ramifications of childhood hypertension. IPHA sponsors scientific symposia at the Pediatric Academic Societies and American Society of Hypertension annual meetings. We also collaborate with the International Pediatric Nephrology Association in developing scientific programming for its congresses, and have co-sponsored programming at the American Society of Nephrology's annual meeting.
Conflict of Interest:
None declared