A higher body mass index (BMI) in adolescence is strongly associated with the risk of all-cause mortality, heart failure, and ischemic stroke in men who are diagnosed with atrial fibrillation (AF) in adulthood, according to a study in the Journal of the American Heart Association.
Researchers sought to assess the relationship of BMI in adolescence with later diagnosis of AF based on data from conscripts into military service from 1969 through 2005 from the Swedish Military Service Conscription Register. Women, men aged younger than 15 and older than 40 years, and those with missing BMI data were excluded.
Data were also obtained from the Swedish National Inpatient Registry and the Hospital Register and Cause of Death Register. Records were reviewed from conscription date until initial AF diagnosis, death, emigration, or December 31, 2019, whichever occurred first.
A total of 1,704,467 men (mean age, 18.3±0.75 years) were included. The median follow-up was 32 years and 36,693 men were diagnosed with AF at a median age of 52.4 years.
After a maximum 50-year follow-up through December 31, 2019, the cumulative incidence rate of AF was 20% in men with obesity at baseline, 12.4% in men who were overweight, 8.3% in men with a BMI of 20 to 25, and 6.5% in men with a BMI of less than 20.
Using 18.5 to 20.0as the BMI reference, the adjusted risk for AF at low-normal BMI levels of 20.0 to 22.5 resulted in a hazard ratio (HR) of 1.06 (95% CI, 1.03-1.10), which gradually increased to 3.72 (95% CI, 2.44-5.66) with a BMI of 40 to 50.
According to the multivariable-adjusted models, age, conscription year, systolic blood pressure, cardiorespiratory fitness, intelligence quotient, and baseline comorbidities were independent predictors of AF.
Among the men with AF, 3767 deaths occurred, for a rate of 13.2 cases per 1000 person-years, increasing to 13.0 per 1000 person-years in those with BMI less than 20, and to 22.6 per 1000 person-years for those with a BMI higher than 30. In addition, 3251 men had heart failure and 921 had ischemic stroke.
The rate of all-cause mortality after a maximum 10-year follow-up post-AF index diagnosis was 19.1% in men with obesity, 16.8% in men who were overweight, 11.4% in those with a BMI of 20 to 25, and 11.7% in men with BMI less than 20.
Participants with BMI higher than 30 in adolescence had a multivariable adjusted hazard ratio (HR) for all-cause mortality of 2.86 (95% CI, 2.30-3.56) compared with those who had BMI of less than 20, with an 8.8% increased risk of all-cause mortality per BMI unit.
Men with obesity or who were overweight had a significantly increased multivariable adjusted HR for incident heart failure (HR, 3.42 [95% CI, 2.50-4.68] and HR, 2.17 [95% CI, 1.73-2.72], respectively) vs men with a BMI of less than 20. Men with AF and a BMI higher than 30 at baseline had an increased risk for ischemic stroke (HR, 2.34 [95% CI, 1.52-3.61]) vs those with a BMI less than 20 in adjusted models.
Among several study limitations, BMI is used as a proxy for overweight and obesity, and the data and statistical analysis did not account for BMI variation over time. Also, the population is homogeneous regarding sex and ethnicity, comorbid medical diagnoses are not accounted for, and data on oral anticoagulant use are lacking.
“Assessment of long-standing and early-onset obesity among men diagnosed with AF could help to identify individuals with a particularly high risk of clinical outcomes, such as all-cause mortality, heart failure, and ischemic stroke,” wrote the study authors.
Djekic D, Lindgren M, Åberg ND, et al. Body mass index in adolescence and long-term risk of early incident atrial fibrillation and subsequent mortality, heart failure, and ischemic stroke. J Am Heart Assoc. Published online October 19, 2022. doi: 10.1161/JAHA.121.025984