Neck Circumference and Risk of Incident Atrial Fibrillation in the Framingham Heart Study

Abstract

Background Increased neck circumference, a proxy for upper-body subcutaneous fat, is associated with cardiovascular risk and metabolic risk factors, accounting for body mass index (BMI) and waist circumference. The association between neck circumference and incident atrial fibrillation (AF) is unclear. The aim of current study was to evaluate the association between neck circumference and incident AF. Methods and Results We selected participants from the Framingham Heart Study aged ≥55 years without diagnosed AF and with available neck circumference, BMI, and waist circumference measurements. We defined high neck circumference as ≥14 inches in women and ≥17 inches in men on the basis of the Contal and O'Quigley changepoint method. We used Fine-Gray models to estimate subdistribution hazards ratios (sHRs) for the association between neck circumference and incident AF accounting for the competing risk of death. We adjusted models for clinical risk factors. We then additionally adjusted separately for BMI, waist circumference, and height/weight. The study sample included 4093 participants (mean age 64±7 years, 55% female). During 11.2±5.7 mean years of follow-up, incident AF occurred in 571 participants. High neck circumference was associated with incident AF (sHR for high versus low: 1.58; 95% CI, 1.32-1.90, P<0.0001). The association remained significant after adjustment for BMI (sHR, 1.51; 95% CI, 1.21-1.89; P=0.0003), waist circumference (sHR, 1.47; 95% CI, 1.18-1.83; P<0.0001), and height/weight (sHR, 1.37; 95% CI, 1.09-1.72; P=0.007). Conclusions High neck circumference was associated with incident AF adjusting for traditional adiposity measures such as BMI and waist circumference.

Keywords: atrial fibrillation; epidemiology; fat depot; incidence; neck circumference.

Figure 1. Flow chart of study sample selection.

AF indicates atrial fibrillation; BMI, body mass index; and FHS, Framingham Heart Study.

Figure 2. Restricted cubic splines for the association between neck circumference and risk of AF, by sex (top panel).

The x axis (in the middle) represents neck circumference in women and men in inches for top and bottom panels. The y axis reports subdistributional hazard ratios (95% CI) of incident AF (top panel) or N (bottom panel). Curves are adjusted for the mean level of age, sex, systolic and diastolic blood pressure, hypertension treatment, diabetes, current smoking, history of heart failure, and history of myocardial infarction. The P‐value for the test of overall significance of the curve was <0.0001 for both women and men. Distribution of neck circumference by sex (bottom panel). AF indicates atrial fibrillation; and HR, hazard ratio.

Figure 3. Cumulative incidence function for AF by neck circumference classification (high vs low).

Curves are adjusted for the mean level of age, sex, systolic and diastolic blood pressure, hypertension treatment, diabetes, current smoking, history of heart failure, and history of myocardial infarction and are adjusted for the competing risk of mortality. AF indicates atrial fibrillation.