[Definition of hypertension based on a prevalence study of 1,423 young adults].

The prevalence of arterial hypertension (AH) was studied in 1423 individuals (702 males and 721 females) aged 21 years (Fig. 1, Table 1). Systolic (SBP) and diastolic (DBP) blood pressures and heart rate (HR) were measured three times on two different occasions separated by at least one week. Three different criteria were used to define AH (Table 3): 1) World Health Organization (WHO) [PAD > or = 95 mmHg in one casual determination]; Joint National Committee IV (JNC-4) [PAD > or = 90 mmHg on two different occasions]; and 3) Statistical [PAD > percentile 95 of the respective distribution]. BP was distributed normally in both males and females (Fig. 4). DBP decreased progressively along the six measurements (Fig. 2, Table 2), with the average of DBP determinations 4-6 being significantly lower than the average of determinations 1-3 (p < 0.05). SBP behaved in the same way (Fig. 2, Table 2), but in this case the 2nd and 3rd determinations within each occasion (2-3 and 5-6) were significantly lower than determinations 1 and 4, respectively (p < 0.05). As a result, the percentage of individuals of either sex with DBP > 90 mmHg was 14.7% based on the 1st determination (Fig. 5), but if the averages of determinations 1 to 3 or 1 to 6 were considered, these percentages decreased to 8.7% and 4% respectively (Fig. 5). With the WHO criterion (PAD > or = 160/95 mmHg based on the first determination) there were 3.3% of individuals with AH. With the statistical criterion the prevalence of AH was always 5%, but the actual value of percentile 95 was progressively lower as we took into account the 1st. determination, the average of 1-3 or the average of 1-6: 100, 95 and 90 mmHg in males and 90, 88 and 84 mmHg in females, respectively (Fig. 6). With the JNC-4 criterion there were 1.6% of individuals with AH (Fig. 5). These low figures were caused by the lack of repeatability of DBP readings in the second determination, since 79% of the individuals with DBP > or = 90 mmHg on the first occasion were normotensive on the second one, whereas more than 95% of those being initially normotensive remained in that category on the second visit (Fig. 7). The FC did not show important changes (Fig. 8), and the percentage of individuals with systolic AH was low (Table 4).(ABSTRACT TRUNCATED AT 250 WORDS)