Blood pressure and its influencing factors in a national representative sample of Iranian children and adolescents: the CASPIAN Study

Background This study was performed to determine the blood pressure (BP) percentile curves by height, as well as to assess the prevalence of high BP and its influencing factors among children in the first national survey in this field in Iran. Design A multicentre national cross-sectional survey. Methods This study was performed in 23 provinces among a representative sample of 21111 students aged 6–18 years. Results Age and sex-specific percentile curves of systolic and diastolic BP were obtained by height. A comparison of the values obtained corresponding to the 90th percentiles with the Second Task Force cut-offs showed that the BP values and trends were relatively similar in both studies. The overall prevalence of systolic, diastolic as well as systolic or diastolic hypertension according to the Second Task Force study 95th percentile cut-off points were 4.2, 5.4 and 7.7%, respectively, without a significant sex difference. A history of low birthweight, overweight, taller height, the consumption of solid hydrogenated fat, as well as the frequency of fast food consumption increased the risk of both systolic and diastolic hypertension. Male sex, large waist, and low education of the mother were the risks for systolic hypertension, whereas the risk of diastolic hypertension rose with living in an urban area, attending public school, low physical activity level, having a housewife mother, and a positive family history of obesity, especially in the parents. Conclusion Considering the effect of modifiable environmental factors on the childrens' BP, encouraging breast feeding and a healthy lifestyle may have an important effect on public health.