Statistics
We tested the homogeneity of variances using Bartlett’s test for each parameter by age, and depending on the result, ANOVA or a Kruskal-Wallis test was used to examine differences among the age groups. The Bonferroni post-hoc test was applied to verify pairwise differences between the means by ages if the ANOVA or Kruskal-Wallis test yielded a p-value less than 0.05, and age intervals with similar means were combined. Bartlett’s test was applied to the new age groups, followed by ANOVA or a Kruskal-Wallis test to check whether the new age groups maintained the age categorization. We excluded outliers (±3 standard deviations from the mean), and the RI was established as the resulting mean ±2 standard deviations. In addition, we calculated the percentile distribution to establish the RIs and adopted the criteria of the NHLBI Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents [5] as a proposed decision limit for this population. For TC, nHDL-c, LDL-c and TG, values below the 75th percentile were considered desirable or acceptable. Values from the 75th to approximately the 95th percentile were considered borderline, and values greater than or equal to the 95th percentile were considered high. For HDL-c, the 10th percentile was used as the lower limit. Therefore, the participants below the 10th percentile were considered to have a low concentration. A concentration above the 50th percentile was considered desirable. The significance level was 5% for all tests. The statistical analyses were performed using Minitab software, version 15 (Minitab, PA, USA) and SPSS, version 16 (Chicago, Illinois, USA).