Waist circunference references for children and adolescents from 6 to 18 year-old from the autonomous region of Madeira, Portugal [Referências para o perímetro da cintura de crianças e jovens dos 6 aos 18 anos de idade da região autónoma da Madeira, Portugal]

Abstract

Waist circumference (WC) has been associated with cardiometabolic diseases. We aim to develop WC references for age and gender in youngsters in Autonomous Region of Madeira, Portugal (RAM). A cross-sectional study was developed in two phases. Between May 2004 and May 2005 (in 1st cycle schools) and between October 2007 and June 2009 (in 2nd and 3rd cycle, and secondary and professional schools). A representative sample of 6987 individuals was gathered, with 3532 girls and 3455 boys aged from 6 to 18 years old. WC was measured with a non-elastic tape at the midpoint between the iliac crest and the last rib. To elaborate smoothed percentiles and z-scores curves for age and gender, values were estimated between 72 and 225 months (every three months) using the LMS statistical procedure, with the exponent of the Box-Cox (L), the median (M), and coefficient of variation generalized (S) through LMSChartMaker software, version 2.76. Mean and standard deviation and charts of smoothed percentiles curves (P3, P5, P10, P25, P50, P75, P85, P90, P95 and P97) and z-scores (-2, -1, 0, 1 and 2) are presented by age and gender. These references constitute a new tool to assess cardiometabolic risk of RAM's children and adolescents.