What is the clinical evidence from this study?

Study design: Cohort. Population: Atrial fibrillation (n=44135). Intervention: General obesity (BMI ≥ 28 kg/m²) vs. Normal weight (BMI 18.5-23.9 kg/m²). Primary outcome: Incident atrial fibrillation (HR 1.73, 95% CI 1.31-2.30).

June 29, 2022BMC Medicine34 citationsOpen Access

Elevated levels of body mass index and waist circumference, but not high variability, are associated with an increased risk of atrial fibrillation

MZMaoxiang Zhao LSLulu Song QZQianqian Zhao

Key Result

General obesity and abdominal obesity were associated with an increased risk of incident atrial fibrillation compared to normal weight and waist circumference (HR 1.73 and 1.38, respectively), whereas variability in these measures was not.

Study Design

Type

Cohort (n=44,135)

Multicenter

Yes

Structured PICO

Do elevated levels and high variability of body mass index and waist circumference increase the risk of incident atrial fibrillation in a Chinese cohort?

Population

44,135 Chinese adults free of cardiovascular disease and cancer, followed for a mean of 9.68 years to assess the risk of incident atrial fibrillation.

Exposure

Elevated levels of body mass index (BMI ≥ 24 kg/m²) and waist circumference (WC ≥ 90 cm for men, ≥ 80 cm for women), and their variability over time.

Comparator

Normal body mass index (18.5-23.9 kg/m²) and normal waist circumference.

Outcome

First occurrence of atrial fibrillation (AF) ascertained from insurance/hospital registers and biennial ECGs.hard clinical

Elevated levels of BMI and waist circumference, but not their variability, are independently associated with an increased risk of incident atrial fibrillation.

Main Result

Hazard Ratio: 1.73 (95% CI 1.31–2.3)

Absolute Event Rate: 1.39% vs 0.8%

Limitations

Observational study design precludes determining causality.
Classification of types of AF was not available.
AF cases were mainly ascertained through hospital discharge codes, potentially missing asymptomatic or undiagnosed cases.
Variability of BMI and WC was measured based on only three time points, potentially underestimating variability.
Study sample was limited to a Chinese occupational population, limiting generalizability.
Observational study design cannot determine causality
Classification of types of AF was not available
Asymptomatic or undiagnosed AF cases might have been missed, potentially underestimating new-onset AF
Variability of BMI and WC measured based on only three time points
Limited generalizability as the sample was restricted to a Chinese occupational population

Abstract

BACKGROUND: Although obesity has been associated with risk of atrial fibrillation (AF), the associations of variability of obesity measures with AF risk are uncertain, and longitudinal studies among Chinese population are still lacking. We aimed to evaluate the impacts of obesity and variability of body mass index (BMI) and waist circumference (WC) on the risk of atrial fibrillation (AF) in a large Chinese cohort study. METHODS: A total of 44,135 participants of the Kailuan Study who were free of cancer and cardiovascular disease and underwent three consecutive surveys from 2006 to 2010 were followed for incident AF until 2020. Average BMI and WC over time and variability were calculated. Cox proportional hazards regression models were used to assess hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of obesity and variability in BMI and WC with AF risk. RESULTS: During a mean follow-up of 9.68 years, there were 410 cases of incident AF. In multivariable-adjusted models, compared with normal BMI/WC, individuals with general obesity and abdominal obesity had increased risk of AF, with corresponding HRs of 1.73 (95% CI: 1.31-2.30) and 1.38 (95% CI: 1.11-1.60), respectively. The short-term elevation in AF risk persisted for the obese even after adjustment for updated biologic intermediaries and weight. Variability in BMI and WC were not associated with the risk of AF. The restricted cubic spline models indicated significant linear relationships between levels of WC and BMI and risk of AF. CONCLUSIONS: Elevated levels of BMI and WC were associated with an increased risk of AF, whereas variability in BMI and WC were not. Therefore, achieving optimal levels of BMI and WC could be valuable in AF prevention.

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