Low body-mass index with abdominal obesity is associated with worse heart failure outcomes in Asian

Having a lower body-mass index (BMI), but also having a higher waist-to-height ratio (WHtR), is associated with worse outcomes among Asian patients with heart failure, according to a study published September 24 in the open-access journal PLOS Medicine by Carolyn Lam of the National Heart Centre Singapore, and colleagues. As noted by the authors, the combined use of BMI and abdominal measures could potentially inform heart failure management better, especially among the particularly vulnerable patients with low BMI and high WHtR in Asia.

Among heart failure patients, Asian patients are more likely to be lean (have a low BMI, <24.5 kg/m2 ) than Western patients. The obesity paradox, in which higher BMI is associated with better heart failure outcomes, has been mainly reported in Western nations using the traditional classification of obesity (BMI), but little is known about this paradox in Asia. To address this gap in knowledge, Lam and colleagues investigated the association between obesity (defined by BMI and abdominal measures) and heart failure outcomes in Asia. Using a heart failure registry for 11 Asian regions, the researchers prospectively examined 5,964 patients with symptomatic heart failure, among whom 2,051 also had WHtR measurements, and examined one-year composite outcomes (i.e., heart failure hospitalization or mortality).

Higher BMI was associated with better outcomes but higher WhtR was associated with worse outcomes. In combined analysis, the "lean-fat" subgroup with low BMI and high WHtR (≥0.55) made up 13.9% of the heart failure population in Asia, were more likely to be women (35.4%) from low-income countries (47.7%), predominantly in South/Southeast Asia, had the highest prevalence of diabetes (46%), worst quality-of-life scores (63.3 ± 24.2), and highest rate of composite events ([51/232], 22%), compared to other subgroups (p<0.05 for all). In addition, the lean-fat group had the highest adjusted risk of composite outcomes (hazard ratio [HR]: 1.93, 95%CI 1.17-3.18, p=0.01), compared to the obese-thin group with high BMI and low WHtR. Findings were consistent across both heart failure with preserved and reduced ejection fraction (HFpEF and HFrEF). Taken together, the findings suggest that the obesity paradox exists in Asia, but only when classified by BMI and not abdominal measures. A direct relationship between central obesity and heart failure outcomes is apparent in both HFpEF and HFrEF.

According to the authors, clear national policies that underscore the prevention of abdominal obesity and the promotion of a healthy BMI through awareness, education and lifestyle modification should be championed. The authors note that because these analyses were based on data from multinational registries, they may be affected by selection bias and unmeasured confounding.