Tracking of systolic blood pressure during childhood: a 15-year follow-up population-based family study in eastern Finland

Objectives To investigate the tracking of systolic arterial blood pressure (SBP) during childhood. Design and setting All children born during 1981–82 in a rural community of eastern Finland were followed at the ages of 6 months, 7 and 15 years (SBP-6m, SBP-7y, SBP-15y). One hundred and thirty-eight out of 205 children completed the full follow-up period, of which 100 (45 girls) were included in the analysis with complete data. Main outcome measures SBP (mmHg). Results SBP-6m was associated with SBP-7y (r = 0.715;P< 0.001) and with SBP-15y (r = 0.238;P = 0.017) and SBP-7y was associated with SBP-15y (r = 0.348;P< 0.001). Adjustment for confounders did not change these results. Children at the highest tertile of SBP-6m had a higher probability of being at the highest tertile of SBP-7y [relative risk (RR) = 4.3; 95% confidence interval (CI), (2.4–7.6)] and SBP-15y [RR = 1.9; 95% CI, (1.1–3.3)]. Children at the highest tertile of SBP-7y had a higher probability of being at the highest tertile of SBP-15y [RR = 2.6 (1.5–4.6)]. The regression analysis showed a significant main effect on SBP-15y for birth weight (negative association), male gender, current body mass index (BMI), change of BMI between the ages of 7 years and 15 years, SBP–6m, SBP-7y and the mean SBP between the ages of 6 months and 7 years (all with positive association). Children with family history of hypertension appear to have a higher SBP during childhood; however, this association did not reach a significant level. Conclusions The study confirmed the tracking of SBP during childhood. Birth weight was inversely associated with SBP-15y. Family history of hypertension was not significantly associated with SBP during childhood.