A comparison of the association of fat-to-muscle ratio vs. BMI and hypertension: A US population-based study

ObjectiveHypertension is the leading cause of preventable cardiovascular disease (CVD) and is associated with obesity. Body mass index (BMI), the most common measure of obesity, does not distinguish between fat and muscle mass. By contrast, dual-energy X-ray absorptiometry (DXA) is the gold standard for measuring fat composition with high accuracy and minimal variability. To our knowledge, no United States studies have examined the association between BMI or fat-to-muscle-ratio (FTMR) (using DXA) and hypertension. MethodsWe analyzed NHANES data of adults aged 20-59 years from 5 consecutive cycles (2011-2012 through 2017-2018). The primary outcome was hypertension. Logistic regression was used to determine the associations between FTMR and odds of hypertension, and between BMI and hypertension. ResultsThe mean FTMR was higher in the hypertension compared to the non-hypertension group (0.57 {+/-} 0.01 vs. 0.53 {+/-} 0.004, p < 0.001), with a similar pattern observed for BMI (32.3 {+/-} 0.2 vs. 28.1 {+/-} 0.1, p < 0.001). Logistic regression analysis showed each one-unit increase in FTMR was associated with 2.80 times higher odds of hypertension, while each 1 kg/m{superscript 2} increase in BMI was associated with 1.08 times higher odds. The sex specific odds ratio (OR) for FTMR were even higher after adjusting for age (males 24.58 (11.74-51.46), females 8.77 (5.04-15.26), p<0.001). However, after adjusting for sex in a receiver operator curve (ROC) analysis, FTMR (Area Under the Curve [AUC] 0.63; 95% CI 0.62-0.64) did not outperform BMI (AUC 0.67; 95% CI 0.66-0.68) regarding their association with hypertension. ConclusionAlthough logistic regression showed a stronger relation of FTMR than BMI and the odds of hypertension, the ROC curve indicated no difference in association of hypertension and FTMR and BMI. Further research should examine the ability of FTMR compared to BMI to predict hypertension and CVD related-complications in high-risk subgroups.