To analyse the incidence, prevalence, aetiology, risk factors and prognosis of hospitalizations for atrial fibrillation. A random population sample of 7495 men aged 47-55 years was first examined in 1970-73. During follow-up until 1996 (mean 25.2 years) 754 men were hospitalized with a diagnosis of atrial fibrillation. In the age groups of 55-64, 65-74 and 75-79 years, the incidence rate was 2.0, 5.8 and 17.3 per 1000 person years, and the prevalence 1.2, 4.2 and 8.0%, respectively. Definite or possible coronary heart disease was diagnosed in 46.0%, heart failure in further 20.2% and valvular heart disease or cardiomyopathy in 4.5%. In bivariate analysis adjusted for age, the following factors were significantly associated with future hospitalization for fibrillation: a family history of myocardial infarction, stroke in mother, dyspnoea at entry, alcohol abuse, high body stature and body weight, high blood pressure but not diabetes, high serum cholesterol, high heart rate, smoking, coffee consumption or psychological stress. Significant risk factors in multivariate analysis were age, odds ratio (OR) [95% confidence interval (CI)] -1.11 (1.07, 1.16) per year, hospitalization for coronary heart disease or heart failure -6.77 (5.17, 8.87), stroke in mother - 1.49 (1.15, 1.93), high body stature -1.04 (1.03, 1.06) per cm, high body mass index (BMI) -1.07 (1.04, 1.10) per kg m(-2), as well as hypertension -1.33 (1.07, 1.65). After a diagnosis of atrial fibrillation, mortality was increased by 3.3 times. In spite of a clinical association with coronary heart disease, risk factors for atrial fibrillation were only partly the same. Prevention includes avoidance of weight gain and control of blood pressure as well as prevention of myocardial infarction and heart failure.
