Prevalence of atrial fibrillation in the Portuguese population aged 40 and over: the FAMA study

Abstract

Introduction: Atrial fibrillation (AF) is the most frequently encountered arrhythmia in clinical practice, and is an important cause of morbidity and an independent risk factor for overall mortality and sudden death. This study aims to assess the prevalence of AF in individuals aged 40 and over in order to characterize the situation in Portugal and improve the detection and management of this arrhythmia.

Methods: This was a cross-sectional study of a representative sample of the Portuguese population including subjects of both genders aged 40 and over, resident in Portugal. The sample was constructed using a random route method. The determination of AF prevalence was based on the results of ECGs, the rhythm being classified by a panel of cardiologists; a questionnaire was used to characterize the AF population by collecting demographic, socioeconomic, clinical, and therapeutic data.

Results: Of the 10,447 individuals included, 55% were female and the median age was 58 years (min=40; max=101). Two hundred and sixty-one cases of AF were identified, representing a prevalence of 2.5% (2.2-2.8%: 95% CI). No differences were found between genders, but AF prevalence increased with age, the prevalence being significantly higher in the group aged 70 and over (70-79: 6.6%; 80 and over: 10.4%). According to this study, the typical AF patient has a median age of 77, is overweight (mean BMI = 27.7 kg/m2), and does not exercise, smoke or consume alcohol. Logistic regression analysis identified male gender (OR: 1.689), age (OR: 1.094), BMI (OR: 1.056), hypertension (OR: 1.437), and lack of physical exercise (OR: 0.436) as risk factors. Only 1.6% of AF cases had known AF, usually diagnosed by a cardiologist (61%) based on an ECG (97.4%). Less than half of the patients were taking oral anticoagulants (38%).

Conclusions: AF prevalence in the Portuguese population aged 40 and over is relatively high compared to studies carried out in other countries. As AF is a common arrhythmia and is a risk factor for stroke, it is essential to promote prevention strategies. It is important to control hypertension, reduce obesity, and establish screening programs in order to maximize the number of identified cases and optimize those patients' treatment, particularly in preventing the associated thromboembolic risk.