Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Absolute height-specific thresholds to identify elevated blood pressure in children Arnaud Chiolero a , Gilles Paradis b , Giacomo D. Simonetti c , and Pascal Bovet a,d Objective: Identification of children with elevated blood pressure (BP) is difficult because of the multiple sex, age, and height-specific thresholds to define elevated BP. We propose a simple set of absolute height-specific BP thresholds and evaluate their performance to identify children with elevated BP in two different populations. Methods: Using the 95th sex, age, and relative-height BP US thresholds to define elevated BP in children (standard criteria), we derived a set of (non sex- and non age- specific) absolute height-specific BP thresholds for 11 height categories by 10 cm increments. Using data from large school-based surveys conducted in Switzerland (N ¼ 5207; 2621 boys, 2586 girls; age range: 10.1–14.9 years) and in the Seychelles (N ¼ 25 759; 13 048 boys, 12 711 girls; age range: 4.4–18.8 years), we evaluated the performance of these height-specific thresholds to identify children with elevated BP. We also derived sex-specific absolute height-specific BP thresholds and compared their performance. Results: In the Swiss and the Seychelles surveys, the prevalence of elevated BP (standard criteria) was 11.4 and 9.1%, respectively. The height-specific thresholds to identify elevated BP had a sensitivity of 80 and 84%, a specificity of 99 and 99%, a positive predictive value of 92 and 91%, and a negative predictive value of 97 and 98%, respectively. Performance of sex-specific absolute height- specific BP thresholds was similar. Conclusion: A simple table of height-specific BP thresholds allowed identifying children with elevated BP with high sensitivity and excellent specificity. Keywords: blood pressure, pediatric, predictive value, screening, sensitivity Abbreviations: BP, blood pressure; NPV, negative predictive value; PPV, positive predictive value INTRODUCTION T he identification of children with elevated blood pressure (BP) is difficult notably because the thresholds to define elevated BP are sex, age, and height-specific [1–3]. Consequently, there are numerous thresholds, one for each sex, age, and height strata. Thus, accounting for both sexes, 17 age categories, and seven height percentile categories, the BP references recom- mended in United States [1] and in European [2] guidelines include 476 specific thresholds for the 95th percentile of SBP and DBP of children aged 1–17 years. Furthermore, BP thresholds are defined according to the percentile of height, not according to absolute height [1,2]. Because the recommended BP references are based on data from US children, the US reference height chart should be used to determine the height percentile for a given child. This is problematic because health practitioners in countries outside of the United States are using specific national height charts and height percentiles may substan- tially differ from the US height percentiles. These difficulties deter health professionals to assess elevated BP in children, threaten the validity of the BP assessment when it is done, and may lead to the under- diagnosis of hypertension in children [4]. Therefore, it would be useful for health professionals to have a simpler tool to identify elevated BP in children [5–9]. In this study, we developed simple user-friendly BP thresholds based solely on absolute height and evaluated the performance of these thresholds to identify children with elevated BP in large school-based surveys in two different populations,- that is, Switzerland, a high-income European country [10,11], and the Seychelles, a middle-income African country [12,13]. METHODS Determination of height-absolute blood pressure thresholds We predefined 11 absolute height categories with 10 cm increments, i.e., less than 85 cm, 85–94, 95–104, 105–114, 115–124, 125–134, 135–144, 145–154, 155–164, 165–174, and at least 175 cm, respectively. For each height category, we identified the corresponding US height percentile for Journal of Hypertension 2013, 31:1170–1174 a Institute of Social and Preventive Medicine (IUMSP), University Hospital Center, Lausanne, Switzerland, b Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada, c University Children’s Hospital, Insel- spital and University of Bern, Switzerland and d Ministry of Health, Victoria, Mahe ´, Republic of Seychelles Correspondence to Arnaud Chiolero, MD, PhD, Institute of Social and Preventive Medicine (IUMSP), University Hospital Center (CHUV/UNIL), Biopo ˆ le 2, Route de la Corniche 10, 1010 Lausanne, Switzerland. Tel: +41 21 314 72 72; fax: +41 21 314 73 73; e-mail: arnaud.chiolero@chuv.ch Received 4 December 2012 Revised 8 January 2013 Accepted 15 February 2013 J Hypertens 31:1170–1174 ß 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins. DOI:10.1097/HJH.0b013e32836041ff 1170 www.jhypertension.com Volume 31  Number 6  June 2013 Original Article