[Prevalence of high blood pressure among schoolchildren in Cuiabá, Midwestern Brazil].

OBJECTIVE The ways in which basal blood pressure levels are obtained may lead to different prevalence estimates. The objective of the study was to estimate the prevalence of high blood pressure among schoolchildren and to compare systolic and diastolic means obtained from three measurements of arterial pressure. METHODS This was a cross-sectional study among seven to ten-year-old schoolchildren (N=601) from public and private schools in the urban area of Cuiabá, midwestern Brazil, in 2005. Three different blood pressure measurements at ten-minute intervals were made during a single visit. Children were considered to have high blood pressure when their systolic and/or diastolic blood pressure reached levels greater than or equal to the 95th percentile in the reference table, in accordance with their gender, age and percentile height. To calculate the prevalence, the first and third blood pressure measurements were considered separately. RESULTS There were statistically significant differences between the systolic and diastolic means from the three measurements of the study. The mean systolic and diastolic pressures from the third measurement of the study were 97.2 mmHg (SD=8.68) and 63.1 mmHg (SD=6.66) respectively. The prevalence of high blood pressure was 8.7% (95% CI: 6.4;10.9) from the first measurement and 2.3% (95% CI: 1.1;3.5) from the third measurement. There was no statistical difference in prevalence in relation to age, sex, skin color and type of school. CONCLUSIONS In studies with a single visit, blood pressure measurements decrease significantly from the first to the third measurement. The third measurement seems to reveal blood pressure levels closer to the basal levels.