Search

The never-treated control group in the Oslo Study hypertension trial of middle-aged men 40-49 years old at entry (n = 379) was studied with respect to five-year change in blood pressure and its correlates. The study began in 1972 and ended in 1979, and each patient was followed for five years. Both baseline and rate of change of correlates were analyzed as independent variables versus rate of change in blood pressure as the dependent variable. Rate of change in serum triglycerides were found to be the strongest correlate of rate of change in blood pressure in this population of healthy mild hypertensives. In addition, rate of change in serum cholesterol and body weight made significant contributions in some analyses, but to a lower degree than did rate of change in triglycerides. The model predicts a substantial decrease in blood pressure if lipids and body weight are reduced. Rate of change in sodium, uric acid, and chloride concentrations were also associated with blood pressure change, but total degree of explanation of all explaining variables only accounted for 11-15% of total variation in annual blood pressure change.

Measurements of blood pressure were obtained on 2,673 women from East Boston, Massachusetts, an urban, working class neighborhood, in surveys conducted in both 1973 and 1976-1977. Of these, 927 women participated in a third survey in 1978. The women were 16 to 49 years of age in 1973, premenopausal throughout the study, and not on blood pressure medication. Regression analyses were performed of blood pressure change between the first and second as well as between the second and third surveys on initial blood pressure, age, weight, and patterns of oral contraceptive use. For systolic pressure the effect of starting oral contraceptive use was an increase of 4.1 mmHg (p less than 0.0001), while the effect of discontinuing use relative to continued use was a 4.4 mmHg decrease (p less than 0.0001). These changes were not affected by duration of use or time since last use among past users. For diastolic pressure the average effect of starting use between surveys was an insignificant 1.0 mmHg increase, but diastolic pressure level seemed to increase with duration of use (0.5 mmHg/year, p = 0.0009). The effect of discontinuing use relative to continued use was a drop of 2.7 mmHg in diastolic pressure (p = 0.0004), which was uninfluenced by time since last use.

The determinants of change in blood pressure during childhood were studied in 596 Dutch children, aged 5-19 years. The children were randomly selected from a general population in Zoetermeer, near the Hague, the Netherlands, and this report deals with 462 children (78%), who had three to seven annual measurements of blood pressure between 1975 and 1982. The rate of change in blood pressure was obtained by least-squares regression of blood pressure on time for each subject. Initial level of blood pressure was associated negatively with subsequent change in systolic and diastolic pressure, even after adjustment for regression toward the mean. Parental blood pressure and initial body weight were related positively, but weakly, to the rate of blood pressure change. Initial serum uric acid was associated positively with change in blood pressure in girls only. Vascular reactivity, as measured by the cold pressor test, was not related to the rate of change in blood pressure. The same applied to pulse rate and the use of tobacco, coffee, and oral contraceptives. The finding that children with the highest initial levels of blood pressure did not have the largest subsequent increase suggests that there is no "horse-racing" of blood pressure during childhood. There is some evidence that the relation between initial level and subsequent change in blood pressure is modified by age.

Familial resemblance in the blood pressure response to sodium restriction in normotensive persons was investigated. Forty-four families of identical twin children participated in a sodium restriction (less than or equal to 75 meq/day) protocol for a period of 12 weeks. Subjects were residents of central Indiana, and the study was conducted over a three-year period. Parent-offspring and sibling-sibling resemblances for actual blood pressure were not different under conditions of ad lib sodium intake versus sodium restriction. Mother-offspring resemblance in blood pressure change with sodium restriction was significant for systolic (p less than 0.001), diastolic (p less than 0.05), and mean arterial (p less than 0.05) pressures. Sibling-sibling and twin-twin resemblances were also highly significant for the change in all three blood pressures. Father-offspring resemblances were marginal (p less than 0.10). This study is, to the author's knowledge, the first to demonstrate significant familial resemblances in blood pressure change with sodium restriction in normotensive persons.