Objective and methods: The study aimed at evaluating, in a large sample of Italian children, the reclassification of blood pressure categories with the new U.S. nomograms, obtained in a population of normal-weight children (American Academy of Pediatrics Clinical Practice Guidelines, AAP-CPG), compared with the Fourth Report/European Society of Hypertension (ESH) nomograms. The performance of the two classifications in identifying the presence of left ventricular hypertrophy was also assessed. Results: In 951 individuals referred to a Pediatric Center for Cardiovascular Risk Prevention, a 12% increase in the prevalence of children with blood pressure at least 90th percentile was observed by using the new nomograms. In the subsample of children aged at least 13 years, the application of the blood pressure fixed cutoff values of 120/<80 mmHg (for 'elevated' blood pressure) and of 130/80 mmHg (for hypertension) led to a change in the blood pressure category (worse or better) in about 30% of cases as compared with the AAP-CPG classification based on percentiles. Regarding the identification of individuals with left ventricular hypertrophy, the AAP-CPG classification led to an increase in the true positive fraction (sensitivity) of 5.5%, and to an increment of the false-positive fraction (1 - specificity) of 5.8%. The logistic regression model, adjusted for possible confounding factors, and the ROC curves obtained from the linear predictor of the model showed an identical performance of the Fourth Report/ESH and the AAP-CPG classifications. Conclusion: In our paediatric population, the AAP-CPG classification slightly increased the prevalence of elevated blood pressure values compared with the Fourth Report/ESH classification. Moreover, the application of more 'physiological' nomograms, based on a population of normal-weight children, did not yield any advantage in identifying individuals with early cardiac organ damage.
