Central obesity – ABC CARDIOL

ABC

Original Article

The Direct Effect of Body Mass Index on Cardiovascular Outcomes among Participants Without Central Obesity by Targeted Maximum Likelihood Estimation

Hossein Mozafar Saadati et al. Siamak Sabour Mohammad Ali Mansournia Yadollah Mehrabi Seyed Saeed Hashemi Nazari

Background:

Body mass index (BMI) is the most commonly used index to categorize a person as obese or non-obese, which is subject to important limitations.

Objective:

To evaluate the direct effect of BMI on cardiovascular outcomes among participants without central obesity.

Methods:

This analysis included 14,983 males and females aged 45-75 years from the Atherosclerosis Risk in Communities Study (ARIC). BMI was measured as general obesity, and waist circumference (WC), waist-to-hip ratio (WHR) and hip circumference as central obesity. Targeted maximum likelihood estimation (TMLE) was used to estimate the total effects (TEs) and the controlled direct effects (CDEs). The proportion of TE that would be eliminated if all participants were non-obese regarding central obesity was computed using the proportion eliminated (PE) index. P <0.05 was considered statistically significant. Analyses were performed in the TMLE R package.

Results:

The risk of cardiovascular outcomes attributed to BMI was significantly reversed by eliminating WHR obesity (p<0.001). The proportion eliminated of BMI effects was more tangible for non-obese participants regarding WC (PE=127%; 95%CI (126,128)) and WHR (PE=97%; 95%CI (96,98)) for coronary heart disease (CHD), and WHR (PE=92%; 95%CI (91,94)) for stroke, respectively. With respect to sex, the proportion eliminated of BMI effects was more tangible for non-obese participants regarding WHR (PE=428%; 95%CI (408,439)) for CHD in males, and WC (PE=99%; 95%CI (89,111)) for stroke in females, respectively.

Conclusion:

These results indicate different potential effects of eliminating central obesity on the association between BMI and cardiovascular outcomes for males and females. (Arq Bras Cardiol. 2021; 116(5):879-886)

Read Full Article

ABC

Artigo Original

Criteria for central obesity in a Brazilian population: impact on metabolic syndrome

Paulo José Bastos Barbosa et al. Ínes Lessa Naomar de Almeida Filho Lucélia Batista N. Cunha Magalhães Jenny Araújo

OBJECTIVE: To identify and propose the optimal waist circumference cut-off points (WCp) for the diagnosis of central obesity (CO) in a Brazilian population, so as to compare these cut-off points with those recommended by the ATPIII (WC-ATPIII), and to estimate the difference in prevalence rates of metabolic syndrome (MS) using the two criteria. METHODS: Cross-sectional study conducted in a population subgroup of 1439 adults in the city of Salvador, Brazil. ROC curves of waist circumference (WC) were plotted to identify diabetes mellitus (DM) and obesity. ROC curve sensitivity and specificity values >60% and the closest to each other were used to define WCp. The prevalence of MS was estimated using WCp and WC-ATPIII. RESULTS: Eight hundred and twenty nine women comprised 57.7% of the sample. The WCp selected were 84cm for women and 88cm for men. These cut-off points detected DM with a 68.7% and 70% sensitivity, and a 66.2% and 68.3% specificity, respectively. For obesity, sensitivity and specificity were 79.8% and 77.6% in women and 64.3% and 71.6% in men, respectively. Using WC-ATPIII, 88cm (for women) and 102cm (for men), the sensitivity was 53.3% and 26.5%, respectively, to diagnose DM. For obesity, sensitivity was 66.5% (for women) and 28.6% (for men). The prevalence of MS using WCp was 23.7%, 95%CI (21.6 – 25.9), whereas using WC-ATPIII it was 19.0%, 95%CI (17.1- 20.9), 1.2 times higher using WCp. CONCLUSION: WC-ATPIII were inappropriate and underestimated the prevalence of MS in the population studied, particularly among men. We suggest that the WC cut-off points > 84cm for women and > 88cm for men should be tested in other Brazilian populations.