Physical activity, obesity, weight change, and risk of atrial fibrillation: the Atherosclerosis Risk in Communities study

Abstract

Background: Physical activity (PA) has previously been suggested to attenuate the risk of atrial fibrillation (AF) conferred by excess body weight and weight gain. We prospectively examined the relationship between body size, weight change, and level of PA in a biracial cohort of middle-aged men and women.

Methods and results: Baseline characteristics on risk factor levels were obtained on 14 219 participants from the Atherosclerosis Risk in Communities Study. AF incidence was ascertained from 1987 to 2009. Adjusted Cox proportional hazards models were used to estimate the associations between body mass index, waist circumference, relative weight change, and PA level with incident AF. During follow-up, there were 1775 cases of incident AF. Body mass index and waist circumference were positively associated with AF as was weight loss/gain of >5% initial body weight. An ideal level of PA had a small protective effect on AF risk and partially attenuated the risk of AF associated with excess weight in men but not women: compared with men with a normal body mass index, the risk of AF in obese men with an ideal, intermediate, and poor level of PA at baseline was increased by 37%, 129%, and 156% (Pinteraction=0.04). During follow-up, PA did not modify the association between weight gain and risk of AF.

Conclusions: Obesity and extreme weight change are risk factors for incident AF, whereas being physically active is associated with a small reduction in risk. In men only, being physically active offset some, but not all, of the risk incurred with excess body weight.

Keywords: atrial fibrillation; motor activity; obesity.

Figure 1

Association of relative weight change with incidence of atrial fibrillation in men presented as hazard ratio (solid line) and 95% confidence intervals (shaded area). Results from Cox proportional hazards model using restricted cubic splines, adjusted for age and race. Median value of relative weight change was considered the reference (HR=1). The histograms represent the frequency distribution of the relative weight change in the study sample.

Figure 2

Association of relative weight change with incidence of atrial fibrillation in women. Conventions as in Figure 1.

Figure 3

Hazard ratios for the impact of physical activity level on the association between waist circumference and risk of incident atrial fibrillation(AF) in men after adjustment for confounders. P for interaction between physical activity level and waist circumference on risk of AF = 0.08.