Sex-Specific Associations Between BMI and Waist Circumference in Atrial Fibrillation

Higher body mass index (BMI) and waist circumference are jointly associated with an increased risk for atrial fibrillation (AF) in men and women, cementing the notion that obesity is a clinically important modifiable risk factor for AF, according to study results in the Journal of the American Heart Association.

In this cross-sectional study, investigators evaluated self-referred and self-funded patients who visited a commercial vascular screening clinic between 2008 and 2013 in the US and UK. The researchers calculated each patient’s BMI using self-reported height and weight. Trained personnel measured waist circumference, defined as the smallest perimeter between the last rib and the iliac crest.

They rounded waist circumference values to the nearest inch and defined men and women with abdominal obesity by a waist circumference >102 cm and >88 cm, respectively. The primary outcome of the study was AF prevalence, as determined by a single 12-lead electrocardiogram (ECG).

Of 2,088,728 participants (mean age, 63.6±10.1 years), a total of 12,067 had AF. Baseline BMI was 28.7±5.7 kg/m² for patients with AF vs 27.8±5.3 kg/m² for patients without AF. In addition, mean baseline waist circumference was 102.6±16.4 cm for patients with AF vs 94.1±15.3 cm for patients without AF.

In multivariable logistic regression, a positive association was found between BMI per 5-kg/m² increment and AF (men: odds ratio [OR] 1.65 [95% CI, 1.57-1.73]; women: OR 1.36 [95% CI, 1.3-1.42]; P_trend <.0001) among individuals with a BMI ≥20 kg/m². The investigators also found a higher AF risk with higher usual waist circumference, as demonstrated by an OR of 1.74 (95% CI, 1.55-1.95) for men per 14-cm increase in waist circumference and 1.52 (95% CI, 1.36-1.71) for women per 13-cm increase (P_trend <.0001).

The addition of BMI and waist circumference to fully adjusted models demonstrated a slight improvement of likelihood ratio χ2 in men (1%) and women (9%). Waist circumference showed a stronger improvement of likelihood ratio χ2 compared with BMI in men (30% vs 23%). In contrast, BMI demonstrated stronger improvement of likelihood ratio χ2 than waist circumference in women (23% vs 12%).

A limitation of this study included the use of a single time point ECG, which may have led to an underestimation of AF prevalence in these patients.

According to their findings, the investigators concluded that waist circumference may “be a more informative measure about risk of AF in men and BMI in women,” emphasizing “the importance of sex-specific risk prediction of AF.”

Reference

Poorthuis MHF, Sherliker P, de Borst GJ, et al. Joint associations between body mass index and waist circumference with atrial fibrillation in men and women. J Am Heart Assoc. 2021;10:e019025.