National standards of blood pressure for children and adolescents in Spain: international comparisons. The Spanish Group for the Study of Cardiovascular Risk Factors in Childhood and Youth.

This study determined age-specific patterns of blood pressure (BP) in Spanish children aged 1-18 years for the purpose of developing BP guidelines for this population. Age- and sex-specific BP levels were constructed by pooling data from 15 studies conducted in Spain. Pooled mean BP levels were then compared with those reported by the US Second Task Force on Blood Pressure Control in Children and those recently reported from a separate pooled analysis of the relevant published surveys collected worldwide. In the Spanish data, the average 1-year age increment in Systolic BP (SBP) was uniform for boys and girls until 13 years at 2 mmHg; for boys aged 13-18 the increase was 1.3 mmHg/year; in contrast, girls reached their maximum values at age 13 and the means remained basically unchanged for female adolescents. Fifth-phase diastolic BP (DBP5) values showed a uniform increase for both boys and girls from ages 6 to 18 years at 0.9 mmHg/year. In most age-sex subgroups, mean SBP values were higher (7-8 mmHg on average) in Spain than in the US. However, Spanish values for SBP were in general only slightly higher or approximately equal to those for the international data, from ages 6 to 18 years. The patterns of change in SBP with age differed somewhat in the three data sets. Comparisons for DBP were limited to the age groups for which readings of DBP5 were available. For DBP5, only slight differences between the Spanish and International pools were observed (ages 6-18 compared), but these values were notably higher than those from the US (ages 13-18 compared). These findings suggest that the use of any particular age-based standard to evaluate readings in children in diverse populations cannot be recommended, at least until there is a better understanding of the true differences in BP between populations.