Atrial fibrillation associated with increased risk of venous thromboembolism. A population-based cohort study.

Whether atrial fibrillation (AF) is associated with an increased risk of venous thromboembolism (VTE) remains controversial. From Longitudinal Health Insurance Database 2000 (LHID2000), we identified 11,458 patients newly diagnosed with AF. The comparison group comprised 45,637 patients without AF. Both cohorts were followed up to measure the incidence of deep-vein thrombosis (DVT) and pulmonary embolism (PE). Univariable and multivariable competing-risks regression model and Kaplan-Meier analyses with the use of Aelon-Johansen estimator were used to measure the differences of cumulative incidences of DVT and PE, respectively. The overall incidence rates (per 1,000 person-years) of DVT and PE between the AF group and non-AF groups were 2.69 vs 1.12 (crude hazard ratio [HR]= 1.92; 95 % confidence interval [CI] = 1.54-2.39), 1.55 vs 0.46 (crude HR = 2.68; 95 % CI = 1.97-3.64), respectively. The baseline demographics indicated that the members of the AF group demonstrated a significantly older age and higher proportions of comorbidities than non-AF group. After adjusting for age, sex, and comorbidities, the risks of DVT and PE remained significantly elevated in the AF group compared with the non-AF group (adjusted HR = 1.74; 95 %CI = 1.36-2.24, adjusted HR = 2.18; 95 %CI = 1.51-3.15, respectively). The Kaplan-Meier curve with the use of Aelon-Johansen estimator indicated that the cumulative incidences of DVT and PE were both more significantly elevated in the AF group than in the non-AF group after a long-term follow-up period (p<0.01). In conclusion, the presence of AF is associated with increased risk of VTE after a long-term follow-up period.