Distribution and biosocial correlations of blood pressure levels in Johannesburg blacks.

Blood pressures were measured in a sample of Johannesburg Blacks consisting of 5 018 men and 5 028 women attending the local Labour Bureau. Blood pressure levels correlated positively with age and body mass and were higher in males than females when weight was taken into account. Hypertension was common in both sexes and at most ages; in the 4th decade about one-third of men and women had phase 4 diastolic pressures greater than 90 mmHg. Correlations of blood pressure with a number of social variables were generally unimpressive. There was some evidence that blood pressure was inversely related to educational status and was higher in young adults who (a) lived apart from their families compared with those who lived in family units, and (b) grew up in a rural area and then migrated to Johannesburg compared with those who had lived in Johannesburg all their lives.