Tracking of blood pressure in children: results of 7 years' follow-up. The Nahariya Study.

Four hundred and seventy-five school children initially aged 7, 8 and 9 years were examined for blood pressure and risk factors at intervals over a period of 7 years (1978, 1980 and 1985). A significant correlation between successive blood pressure measurements was found after 2 years of follow-up for systolic blood pressure, with tracking coefficients of 0.16 for boys and 0.22 for girls. A similar correlation was found after 7 years, with correlations of 0.16 and 0.26, respectively. For diastolic blood pressure the correlations were 0.15 and 0.18 after 7 years. Children greater than 7 years old were more likely to be above the 90th percentile, with increasing percentiles found in the initial examination. A significant correlation was found between the initial weight, as recorded in the first examination, and the blood pressure percentiles in all three measurements. The correlation coefficient values increased progressively in the successive examinations--0.11, 0.23 and 0.25, respectively, for systolic pressure, and 0.10, 0.14 and 0.19, respectively, for diastolic pressure. There was significant correlation between the initial body mass index and the blood pressure levels in the last examination. Thus, both initial blood pressure levels and body mass appear to be valid predictors of future blood pressure levels.