1. Sheri L Balsara, Joshua A Samuels, Joyce P Samuel, and Cynthia S Bell University of Texas McGovern Medical School at Houston Pediatric Nephrology and Hypertension Interpretation of the Working Group Definition of Hypertension Methods We performed BP screening at 4 Houston area schools from 2010 to 2015. At each screening visit, height and weight were measured and a minimum of 2 BP measurements were obtained. An average was used as the BP for each screening visit. Any child whose BP was elevated at the first screening visit underwent 2 subsequent BP checks within 2 months of the initial screen. Table 2. Students Counts by Interpretation Definition Conclusions Prevalence of HTN differs depending on how the definition from the Fourth Report is interpreted: Sustained definition: 3.3% HTN Averaged definition: 7.0% HTN The additional hypertensive children by the averaged definition, all of whom were classified as “variable” by sustained definition, were more overweight compared to those that were hypertensive by both definitions. The sustained definition failed to categorize 453 (22%) of those screened because they crossed classifications. Of these children with “variable” BP, 189 (42%) had normal averaged BP, but 264 (58%) had abnormal BP by averaged definition. 453 children (81% of children screened three times) were deemed “variable” by the sustained definition because their BP changed categories across screening visits. Within this variable group, children who were HTN by the averaged definition were more likely to be male (Chi 2 p=0.034), younger (Kruskal-Wallis p=0.001), and have greater BMI (Fisher’s exact p=0.047) compared to children who were normal by the averaged definition. Compared to the 1,535 children with normal BP by both definitions, the 189 children with averaged normal BP but sustained variable BP were more often male with greater weight and BMI percentiles. Conversely compared to the 37 children with pre- HTN BP by both definitions, the 187 children with averaged pre-HTN BP but sustained variable BP were younger, more often female, and had lower weight percentiles. Table 1. Demographics By Interpretation Definition Sustained Definition Averaged Definition NormalPre-HTNStage 1Stage 2Stage 1 or 2VariableTotal Normal153500001891724 Pre-HTN037000187224 Stage 1003401876128 Stage 2000413118 Total153537344314532094 Figure 1. Prevalence of HTN by Interpretation Results Between 2010 and 2015, 2,168 children were screened for elevated BP and 2,094 children had complete data. Among these, mean age was 14.3±2.1 years with 40.2% males and a race distribution roughly matching 2010 Census data for the city of Houston. The majority, 1,535 children, had normal BP on the first screen and did not undergo further testing. Demographics analyzed by interpretation definition are in Table 1. All students were categorized according to the two definitions (Table 2). The sustained definition resulted in a more conservative 3.3% prevalence of HTN whereas the averaged definition yielded a much higher 7.0% prevalence (Fig 1). The additional 77 students classified as HTN by the averaged definition were more overweight (Fisher’s exact p=0.039) but not statistically different in terms of age, gender, race, height, or weight compared to the 69 students classified as hypertensive by both interpretations. Averaged Definition NormalPre-HTNHTN Total Number1724224146 Mean Age (SD) - years 14.2 (2.1) 15.1 (2.0) 13.6 (1.8) % Male36.458.557.5 Race % Asian6.43.64.1 % Black13.516.510.3 % White36.231.737.7 % Hispanic40.741.543.8 % Other/Unknown3.26.74.1 Height Percentile (SD) 46.4 (29.7) 53.3 (27.9) 50.9 (30.8) BMI Percentile (SD) 63.3 (28.1) 73.8 (25.7) 81.9 (21.7) Weight Category % Overweight16.923.220.6 % Obese14.027.240.4 Sustained Definition NormalPre-HTNHTNVariable Total Number15353769453 Mean Age (SD) - years 14.2 (2.1) 16.6 (1.5) 13.6 (1.8) 14.4 (2.1) % Male35.281.152.251.9 Race % Asian6.60.04.4 % Black13.518.98.714.1 % White35.837.836.235.8 % Hispanic40.937.844.941.3 % Other/Unknown3.35.45.84.4 Height Percentile (SD) 46.2 (29.7) 60.8 (26.6) 51.0 (31.7) 50.0 (29.3) BMI Percentile (SD) 63.0 (28.5) 82.4 (18.6) 78.8 (24.6) 75.5 (24.1) Weight Category % Overweight16.432.411.622.5 % Obese12.835.144.926.7