COMPARISON OF 4TH AND 5TH KOROTKOFF DIASTOLIC BLOOD PRESSURES IN 5 TO30 YEAR-OLD INDIVIDUALS - THE BOGALUSA HEART-STUDY

The use of fourth phase Korotkoff sound (K4) versus fifth phase Korotk off sound (K5) for the determination of diastolic blood pressure (DBP) has been a subject of controversy since the indirect method of determ ining arterial blood pressure was described. Using data from the Bogal usa Heart Study, we evaluated the differences between K4 and K5 (K4 - K5) from 4633 subjects 5 to 30 years of age examined between 1987 and 1991. The overall mean difference between K4 and K5 was 9.9 +/- 5.6 mm Hg (mean +/- SD). The average difference was highest in 5 to 8 year o lds, where it measured 12.3 +/- 5.5 mm Hg. The average K4-K5 differenc e fell with increasing age and reached a value of 6.3 +/- 2.6 mm Hg by 25 years of age. For all race/sex groups, the youngest two age groups differed statistically from the oldest age groups in K4-K5 difference (P < .006). There were significant differences between blacks and whi tes (P < .015) and between men and women (P < .001) for subjects betwe en 13 and 17 years of age. Additional analyses were performed with ind ividuals having K5 = 0 added to yield an expanded population of 5117 p ersons. Overall, 9.5% had at least one of six measurements of K5 = 0 a nd most were young subjects: 27% of children 5 to 8 years and 13% of c hildren 9 to 12 years. We conclude that by age 15 there may be no rele vant clinical difference in K4-K5. However, in children, K4 and K5 sho uld be recorded and K4 is a more reproducible measure of diastolic blo od pressure.