A longitudinal study of blood pressure in childhood.

Blood pressures were taken in 609 children aged 6-18 in 163 families, 549 of whom had been studied 4 years earlier. Age and sex adjusted scores were expressed in standard deviation units (SDU). Analysis of variance again revealed the variance of blood pressures within families to be significantly less than among all children in this age group (p is less than 001. There was a significant positive relation between the follow-up and initial readings (regression coefficients: 0.24,p is less than .001 for systolic and 0.14,p = .001 for diastolic pressures). Of 88 children with initial systolic scores greater than 1 SDU above the mean, 65 percent had positive scores at follow-up, and 57 of 81 (70 percent) children with initial systolic scores less than 1 SDU below the mean had negative scores at follow up. These data suggest that stratification of blood pressures within peer groups begins and is detectable in childhood.