Tracking and factors predicting rising in 'tracking quartile' in blood pressure from childhood to adulthood: Odense Schoolchild Study

This prospective study determines the degree of tracking and investigates f actors predicting a rise in blood pressure (BP) quartile in a cohort of 136 9 subjects who were followed for 11 years from childhood into young adultho od. In 900 of these subjects BP, height, weight, physical fitness and BP re sponses to a maximal exercise testing were measured both at baseline and at follow-up. BP, weight, height and body mass index (BMI) were divided into sex-specific quartiles at both examinations. Tracking was evaluated by exam ining the tendency of remaining in the same quartile from baseline to follo w-up and by measuring product-moment correlation coefficients. Tracking in the upper and lower quartile for BP, weight, height and BMI were significan t. Odds ratios for staying in the upper or lower quartile through the follo w-up period ranged from 1.6 to 2.4 for diastolic BP and from 2.1 to 3.1 for systolic BP. The range of correlation coefficients for the anthropometric measurements were 0.57-0.75, for diastolic BP 0.12-0.22 and for systolic BP 0.34-0.36 respectively. Changes in weight or relative weight as well as BP response to an exercise test were the factors which predicted a rise in qu artile through the 11 years of followup. The existence of the inevitable re gression to the mean problem in large longitudinal studies of BP was demons trated by the finding of baseline BP being a significant factor in the pred iction of rising in systolic, diastolic or both systolic and diastolic BP q uartiles.