Background: Current trends in body size, blood pressure, and serum lipids in children are predictors of future disease prevalence. However, there have been no studies of blood pressure and high-density lipoprotein cholesterol (HDL-C) levels in Japanese children.
Methods: We investigated trends in body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), non-HDL-C, and HDL-C using data from annual screenings in 1993 through 2008. The subjects were 14 872 (98.8% of the target population) fifth-graders enrolled in all public schools in the Original Iwata area in Iwata City, Japan. The same examination protocol was used throughout to ensure the uniformity of quality control and the precision of assessment. Trends in the variables in relation to the calendar year were analyzed by using regression models.
Results: In boys, the 95th percentile of BMI increased by 0.09 kg/m²/year. In both sexes, the 5th percentile of BMI decreased by 0.02 to 0.03 kg/m²/year. There was a significant negative correlation between SBP and calendar year, and the 95th percentile of SBP decreased by 0.52 mm Hg/year in boys and by 0.40 mm Hg/year in girls. There was also a significant reduction DBP. However, there were no trends in TC, non-HDL-C, or HDL-C.
Conclusions: The increase in obese and underweight children in Original Iwata was consistent with the findings of a nationwide survey. Although high blood pressure and related risk factors were formerly a serious problem in Japan, blood pressure levels have decreased in schoolchildren from Iwata over the past 15 years.