Tracking of cardiovascular disease risk factor variables in school-age children.

Persistence in ranks (tracking) for cardiovascular disease risk factor variables was examined in 2236 children who were screened three times over a 5-yr period. As expected, the greatest persistence was noted for height (r = 0.47-0.99) and weight (r = 0.70-0.96). Correlation coefficients for systolic blood pressure and diastolic blood pressure ranged from 0.38 to 0.66 and 0.22 to 0.49 respectively. Among lipids, the correlations were highest for serum beta-lipoprotein cholesterol ranging from 0.62 to 0.78. For those children who were at or above the 90th percentile on a risk factor variable during the first examination, a tendency to retain their ranks in the second and third examinations was noted. For systolic blood pressure, 35% of those initially high remained high in the second examination and 30% in the third examination. Correspondingly, for those initially high for beta-lipoprotein cholesterol, 47 and 41% remained high. A linear discriminant model was used to distinguish characteristics of children who persisted at high rankings and those who did not. The model was effective for total and beta-lipoprotein cholesterol, but only moderately so for systolic blood pressure.