Relationship between waist circumference development curve of children and hypertension and risk of hypertension / 中华儿科杂志

<p><b>OBJECTIVE</b>The 85th percentile of waist circumference (WC) is considered an appropriate cutoff for Chinese children in the prediction of cardiovascular risks in previous researches, but the risk for hypertension of moderate WC maybe underestimated. The purpose of this study was to understand the characteristics of the WC curve trajectory of children with hypertension and to determine the appropriate cutoffs for waist circumference for Chinese school-age children and adolescents for predicting hypertension risk factors.</p><p><b>METHODS</b>A total of 8194 Han children aged 7 - 17 years were selected from schools in Suzhou, Hefei, and Chizhou cities in Anhui province by stratified cluster sampling. WC and blood pressure were accurately measured in all subjects. LMS (lambda-mu-sigma) method was used to construct WC centile curves. Optimal WC cutoffs were determined by comparing the performance of different percentile sets of WC cutoffs in predicting hypertension risk factors.</p><p><b>RESULTS</b>The fitted LMS curves of WC for the group of boys with hypertension deviate in parallel from that for the corresponding curve in the entire boy study population with higher WC. The WC curves for the group of girls with hypertension gradually upward deviated from the corresponding curve before 12 years of age and then gradually returned to the corresponding curve. WC of boys at the percentiles of 60 was already associated with an increased risk of hypertension and hazard ratio of WC at percentiles of 60, 70, 80, and 90 increased from 1.88(95%CI: 1.18 - 2.99) to 4.87 (95%CI: 3.31 - 7.16). WC of girls at the percentiles of 70 was already associated with an increased risk of hypertension and hazard ratio of WC at percentiles of 70, 80, and 90 increased from 1.71 (95%CI: 1.07 - 2.73) to 3.32 (95%CI: 2.16 - 5.09).</p><p><b>CONCLUSIONS</b>The WC growth trajectory of children with hypertension varies with gender. WC is an independent predictor of childhood hypertension, even when it is well within what is now defined as the normal range of WC. Thus, it is helpful to prevent the risk of cardiovascular disease of children using the parameter that WC cut-off level lower than 85th percentile.</p>

Association between body mass index and physical fitness index among children and adolescents / 中华流行病学杂志

Objective To explore the relationship between body mass index (BMI) and physical fitness index (PFI) among children and adolescents.Methods The study sample included 8941 students aged 7 to 18 years in Anhui who attended the Physical Fitness and Health Surveillance program of Chinese School Students,in 2010.Within each sex- and age-specific group,students were classified into five BMI categories which were:very low,BMI ＜5th percentile; low,BMI ≥5th but ＜15th percentiles; normal,BMI ≥15th but ＜85th percentiles; high,BMI ≥85th but ＜95th percentiles; and very high,BMI ≥95th percentiles.Z-scores based on urban-rural,sex- and age-specific means and standard deviations were calculated,and the sum of Z-scores for the fitness tests was used as a PFI.Differences in PFI between BMI categories were compared with ANOVA.Sex- and grade-specific regressions of PFI on BMI were done by using a linear model.Results For 8941 students,the PFIs on very low,low,normal,high and very high group were-1.77,-0.91,0.32,-0.17 and -0.54,respectively,and showed an inverted U shape.The normal BMI group students presented the highest PFI.Data from Linear regression analysis revealed that PFI was significantly positively correlated with BMI,while negatively associated with BMI square,which indicated that PFI was the quadratic function of BMI.When BMI was increasing,PFI showed a parabolic curvilinear.Conclusion Relationships between BMI and PFI were parabolic curvilinear among the children and adolescents aged 7 to 18 in Anhui province.