Blood Pressure Aggregation in Families

Familial aggregation of blood pressure (BP) was investigated among Framingham parents, offspring, and spouses. Of 1644 pairs of parents in the Framingham Heart Study cohort, 1141 parent pairs had 2497 blood-related offspring who, along with available spouses, were examined during the years 1971–1975. Familial BP associations were evaluated using BP measurements of adult offspring and similar measurements of parents taken about 25 years previously, when the parents were, on the average, only 5 years older than the offspring. Simple correlation coefficients between BP in parents and offspring confirm the frequently reported positive association. After adjustment for BP correlates known to aggregate in families, significant partial correlations are still present but are somewhat lower than the simple coefficients. Even after nine previously identified BP correlates are added to a regression equation, both maternal and paternal BP remain as independent predictors of BP in offspring. Simple and partial BP correlation coefficients for male and female siblings are consistent with the relationships found for parents and offspring. Simple spouse BP correlation coefficients are lower than those found in first degree relatives; and, after adjustment for known BP correlates, they disappear in offspring spouse pairs. These findings suggest that the association of spouse BPs results largely from assortative marriage for age and body weight and that much of the association in blood relatives is due to as yet unidentified genetic similarities.