Simple risk model and score for predicting of incident atrial fibrillation in Japanese.

BACKGROUND: Investigating regarding a predicted risk score of incident atrial fibrillation (AF) for an Asian general population has not been enough. Whether addition of electrocardiogram (ECG) variables to risk factors improves prediction of incident AF is unclear in a context that ECGs are extensively used at medical check-ups and outpatient clinics in Japan. METHODS: Participants undergoing periodic health check-ups during 2008-2014 followed-up by December 2015 including 96,841 (65.1% male) aged 40-79 years were pooled to derive prediction models and risk scores for incident AF. Multivariable Cox regression identified clinical risk factors associated with incident AF in 7 years among 65,984 eligible participants including 349 AF cases. RESULTS: A 7-year prediction model ("Simple-model") including the variables of age, waist circumference, diastolic blood pressure, alcohol consumption, heart rate, and cardiac murmur, had good discrimination (C-statistic, 0.77), requiring no blood sampling. Addition model of the ECGs variables ("Added-model") including left ventricular hypertrophy, atrial enlargement, atrial premature contraction, and ventricular premature contraction, improved significantly the overall model discrimination (C-statistic, 0.78; categorical net reclassification improvement, 0.063; 95%CI, 0.031-0.099). The risk scores derived from the two models respectively showed an approximation of the observed and predicted probability for each score. Participants with score ≤4 or ≥9 points had, respectively, ≤1% and ≥5% predicted probability of incident AF in 7 years. The receiver-operating characteristics curve for the risk score of the added-model was significantly higher than the simple-model (0.769 vs 0.753, p<0.001). Atrial enlargement on ECG and the highest age group were the highest risk points of the significant predictors. CONCLUSIONS: We developed 7-year risk scores for incident AF using usually available clinical factors including ECGs in primary care. These risk scores could identify individuals with high risk of incident AF at health check-up and outpatient clinics.

Influence of abdominal obesity and habitual behaviors on incident atrial fibrillation in Japanese.

BACKGROUND: As atrial fibrillation (AF) increases with the aging of the population, it is urgently required to clarify modifiable factors to prevent AF. However, evidence regarding the independent influence of abdominal-obesity and habitual behaviors on incident AF is limited among Japanese. METHODS AND RESULTS: Those aged 40-79 years undergoing periodic health checkups during 2008-2014 were followed-up in 2015 (n=96,841) and the independent risk of incident AF was estimated using multivariate Cox proportional hazards regression models after adjustment for potential covariates. Participants were classified into four groups according to the baseline body mass index (BMI: kg/m2) (normal-BMI or overweight: < or ≥25) and waist circumference (WC: cm) (normal-WC or abdominal-obesity: < or ≥85 for male, ≥90 for female). Baseline habitual behaviors, smoking status, alcohol intake, and physical activity, were also included as modifiable factors. Among 65,984 eligible participants, 349 developed AF over mean follow-up of 5.5±1.6 years. Increase of both BMI and WC significantly elevated the risk of AF. Compared to the normal-BMI and normal-WC group, the normal-BMI but abdominal-obesity and the overweight and abdominal-obesity groups in males and the overweight and abdominal-obesity group in females had significantly elevated risk of AF. Among modifiable behavioral factors including abdominal-obesity, alcohol intake (≥40g/day) and abdominal-obesity significantly elevated the risk of AF in males, and abdominal-obesity was the strongest risk factor in both sexes, but smoking and physical activity were not significant. However, an aggregation of these four behavioral factors increased the risk of AF more than 2.5 times in both sexes. CONCLUSIONS: Abdominal-obesity could be a crucial risk factor in prediction of AF in Japanese, and an aggregation of four behavioral factors increased the risk of AF almost three times. To prevent incident AF, practicing healthy habitual behaviors is recommended.