Geographical differences in blood pressure of male youth aged 17-21 years in China.

Hypertension is one of the most prevalent cardiovascular risk factors in the adult Chinese population. The prevalence distribution of hypertension differs geographically in adults, since hypertension is influenced by environment factors, such as climate, altitude and economic. The aim of the present study was to study the prevalence of hypertension and measure the blood pressure (BP) level, and to compare and observe the geographical distribution of borderline or high BP in Chinese male youth. A cross-sectional survey on constitution and health of Chinese recruit youth was carried out in 2001, using the cluster sampling method. Two to four counties or cantons were selected as survey spots from all the 27 provinces or autonomous regions and four municipalities in China according to its population, geography and economy, except for Hong Kong, Tai Wan and Macao. The total survey spots were 100 counties or cantons. At each survey spot, all the recruit youth aged 17-21 years were surveyed, and data from a total of 81,193 recruits were collected. In the analysis, female youth and male subjects with diseases in heart, kidney, or other organs that could cause high BP were rejected. In all, the analysis sample was 72,895 subjects. Two standardized BP measurements were obtained. According to the P, P centile values of Chinese children and adolescent BP references, and adult's critical hypertension diagnosis standard recommended by the WHO, all the subjects were categorized into seven groups. The relationships between BP and physical indexes, age, heart rate, vital capacity and area were analyzed by using multiple step-wise regression. The prevalence rate of borderline and high BP of male youth in China was 13.3% and 5.0% respectively. There were significant differences in the prevalence rate of relatively high (borderline and high) BP and overall BP among youth from different areas. BP and the prevalence rate of relatively high BP were highest in youth from north China and the northeast areas among the six areas, with a prevalence rate of borderline 25.9% and 14.7%, and the high 10.5% and 5.7% respectively. However, the prevalence rate of relatively high BP of youth from the southwest area was the lowest among the six areas, with a prevalence rate of borderline 5.2% and high 2.3%. The results of multiple step-wise regression analysis showed that height, body mass index, age, heart-rate, vital capacity, economic status were positively correlated with BP, whereas annual mean air temperature, rainfall and altitude were negatively correlated. The results of this study showed that there were significant differences in the prevalence rate of relative high BP in male youth from different areas in China, and that BP was influenced by physical status and living area.