Diastolic Fourth and Fifth Phase Blood Pressure in 10–15-Year-Old Children: The Children and Adolescent Blood Pressure Program

Measurement of diastolic blood pressure is complicated by the presence of two diastolic Korotkoff phases (fourth phase and fifth phase) in many children and adults. In the present study, diastolic fourth phase and diastolic fifth phase were evaluated in 1986-1987 in 19,274 Minneapolis-St. Paul school children aged 10-15 years. Approximately 50 percent of the children had no difference between fourth phase and fifth phase (i.e., fourth phase - fifth phase = 0) and 15 percent had a difference of only 1-4 mmHg. However, the fourth phase - fifth phase difference was 5-10 mmHg in 20 percent, 11-20 mmHg in 11 percent and greater than 21 mmHg in 3 percent of the children. Statistical analyses showed that the fourth phase - fifth phase difference tended to be greater in boys than girls and in older than younger children, was positively related to height, systolic blood pressure and fourth phase blood pressure, and negatively related to body mass index and fifth phase blood pressure. Using fifth phase instead of fourth phase in 10-12-year-old children and fourth phase instead of fifth phase in 13-15-year-old children to define diastolic blood pressures significantly changed the prevalence for significant diastolic hypertension by 2-3 percent.