Systolic blood pressure differences among pediatric epidemiological studies.

This report reviews the results of six large blood pressuree surveys done on pediatric populations and points out factors responsible for differences in the blood pressure norms. The studies were selected on the basis of there being recent examinations of large numbers of children. Important differences in mean systolic pressures and 95th percentile values were found among the studies, which may be attributed to: 1) actual differences among the populations; 2) biases due to methodological differences; or 3) increased sampling variability with small sample sizes. Actual differences in pressures among the populations surveyed may be due to differences in geographic location, racial composition, or average body sizes. Discrepancies due to methodological biases may have occurred because of associated venipuncture or exercise stress on the day of the examination; differences in selection of blood pressure cuff sizes; differences in the number of measurements averaged. In several studies, small sample sizes for each age-race-sex subclass accounted for considerable variability of the 95th percentile value. The implication of this analysis is that before the 95th percentile norms for children of different ages, races, and sexes can be more firmly established, it is necessary to collect larger sample sizes controlling for known biasing factors and using a standardized methodology.