Another (Better) Index of Adiposity

Abstract

TO THE EDITOR: We read with interest the article by Bergman et al. ((1)) proposing a new body adiposity index (BAI). This BAI was developed using a population of Mexican Americans and was crossvalidated on a smaller population of African Americans. Most recently, Barreira et al. ((2)) demonstrated that the BAI and BMI performed similarly in predicting body fat among whites and African Americans but to our knowledge its utility has not been demonstrated when relating to cardiovascular (CV) risk factors in any population. For this reason, we used data from the CoLaus study, a large population-based sample of white participants (3,251 women and 2,937 men, age range 35–75 years) to compute BAI (defined as hip circumference/(height1.5–18)) and to assess its association with CV risk factors and cytokines. The CoLaus Study is a cross-sectional study aimed at assessing the prevalence of CV risk factors as the molecular determinants of CV disease in the white population of Lausanne, Switzerland, a town of 117,161 inhabitants, of which 79,420 are of Swiss nationality. The sampling procedure and methodology have been previously described ((3)). We collected data on adiposity markers (BMI, waist circumference, and body fat as assessed by tetrapolar bioimpedance), CV risk factors (systolic and diastolic blood pressure, total low-density lipoprotein and high-density lipoprotein-cholesterol, triglycerides and glucose), insulin (which enabled the assessment of homeostatic model assessment) and different cytokines (leptin, adiponectin, C-reactive protein, and tumor necrosis factor-α). Levels of these cytokines were measured using a multiplexed particle-based flow cytometric cytokine assay ((4)). We used Spearman nonparametric correlations to assess the relationship between the BAI and all health variables of interest, stratified by gender (Table 1). A stepwise linear regression was run to assess which adiposity markers (BAI, BMI, waist circumference, and body fat) were most associated to CV risk factors (triglycerides were log-transformed) and log-transformed cytokines, again stratifying by gender and controlling for age. The BAI correlated significantly (P < 0.05) and positively with age, other adiposity markers, most CV risk factors, and cytokines, while negative correlations were found for high-density lipoprotein cholesterol and adiponectin. The correlations between BAI and health variables were similar to those between BMI and the health variables (Table 1). Stepwise multivariate linear regression analysis showed that the BAI significantly (P < 0.05) predicted diastolic blood pressure, fasting glucose levels, high-density lipoprotein cholesterol, leptin, and adiponectin in women independently of the other adiposity markers, while no association was found for all other variables. In men, the adiposity index independently and significantly (P < 0.05) predicted adiponectin, high-density lipoprotein-cholesterol and C-reactive protein only. The analysis also showed that, for each gender, the other adiposity markers were associated with more CV and cytokine variables than the new BAI. We conclude that while the new BAI is significantly related to bioelectrical impedance measured body fat, it appears to be of lesser interest than other more established adiposity markers regarding the association with CV risk factors or inflammatory markers. Further studies are welcomed to further assess the clinical utility of the BAI and its relationship to CV risk factors and other health parameters, particularly in diverse populations. The authors declared no conflict of interest.