IJCS | Volume 33, Nº4, July and August 2020

343 Table 2 - Distribution and comparison of clinical characteristics between age groups Age groups < 40 yrs n = 54 40-50 yrs n = 69 > 50 yrs n = 41 p-value a WC (cm) 91.9 ± 16.7 97.7 ± 17.9 99.0 ± 12.8 0.036 SBP (mmHg) 120.9 ± 13.14 126.4 ± 15.3 134.7 ± 14.9 < 0.001 DBP (mmHg) 80.6 ± 10.6 82.7 ± 10.6 87.7 ± 11.9 0.011 Glucose (mg/dL) 96.8 ± 61.3 88.9 ± 20.7 86.9 ± 41.6 0.077 HDL-c (mg/dL) 47.9 ± 8.5 48.9 ± 10.3 51.3 ± 14.0 0.562 Triglycerides ( mg/dL) 126.7 ± 62.3 117.8 ± 63.3 144.5 ± 92.1 0.162 a Kruskal Wallis test. Table 3 - Spearman´s rho correlation coefficients ( ρ ) between increased waist circumference according to the IDF and NCEP-ATPIII criteria and blood pressure, fasting glucose, lipoprotein levels and triglycerides values Total n = 164 IDF NCEP-ATPIII WC < 80 cm n = 26 WC ≥ 80 cm n = 138 WC ≤ 88 cm n = 53 WC > 88 cm n = 111 ρ p-value ρ p-value ρ p-value ρ p-value ρ p-value SBP (mmHg) 0.411 0.000 0.520 0.006 0.285 0.001 0.406 0.003 0.315 0.001 DBP (mmHg) 0.506 0.000 0.411 0.037 0.425 0.000 0.406 0.003 0.442 0.000 Glucose (mg/dL) 0.184 0.018 0.011 0.957 0.183 0.032 0.09 0.524 0.224 0.018 HDL-c (mg/dL) -0.213 0.006 0.026 0.901 -0.270 0.001 0.215 0.122 -0.227 0.017 Triglycerides (mg/dL) 0.172 0.028 -0.031 0.879 0.164 0.056 0.059 0.676 0.225 0.018 and triglycerides showed no difference between the two categories of WC defined by both criteria. Values of age, SBP, DBP, fasting glucose, HDL-c and triglycerides values in the overall cohort was distributed by age group (Table 2). Significant changes were observed between the three age groups in WC (p = 0.036), SBP (p < 0.001) and DBP (p = 0.011). Table 3 shows the correlation coefficients of the studied variables with each WC category according to the IDF andNCEP-ATPIII cut-off values. For participants with increased WC, the analysis showed that the WC categorized by IDF criteria had low correlation with DBP (ρ = 0.425, p = 0.000) and a negligible correlation with SBP, HDL-cholesterol (ρ = 0.285, p < 0.01; ρ = -0.270, p < 0.001, respectively). As for theWC defined by the IDF criteria, we observed a low correlation with SBP, DBP (ρ = 0.315, p = 0.001; and ρ = 0.442, p = 0.000, respectively) and a negligible correlation with HDL-cholesterol and triglycerides (ρ = -0.227, p = 0.017; and ρ = 0.225, p = 0.018, respectively), by the NCEP-ATPIII criterion. Bivariate regression analysis showed that for both criteria, IDF and NCEP-ATPIII, only the variability of SBP, DBP, andHDL-cholesterol levels could be explained by increased WC (Table 4). Among them, DBP showed the highest percentage of variability in the age group > 50 years (27% and 30.5%, respectively). A total of 22.7% and 18.4% in the SBP variability was explained by increased WC in participants aged < 40 years, while 9.8% and 8.5% of the variability inHDL-cholesterol levels was explained by increased WC among participants aged 40-50 years. Silva et al Waist circumference and increased blood pressure Int J Cardiovasc Sci. 2020; 33(4):340-347 Original Article