Comparative thromboembolic risk in atrial fibrillation patients with and without a concurrent infection

Background: The aim of this study was to compare long-term thromboembolic risk in infection-related and non-infection-related atrial fibrillation (AF). Methods: Using Danish nationwide registries, we identified patients with first-time AF from 1996–2015 and performed a retrospective cohort study. We did a 1:1 match (upon sex, age, calendar year, and oral anticoagulation (OAC) status at the beginning of follow-up) of patients with infection-related (concurrent discharge diagnosis code for infection) and non-infection-related AF. Long-term outcomes were examined using multivariable Cox regression analyses. Results: Our study population comprised 48,644 patients equally distributed on infection-related and non-infection-related AF. In both groups, those initiated on OAC therapy were younger than those not initiated on OAC therapy (median age 77 years, interquartile range 69–83 versus median age 79 years, interquartile range 71–86). During the 1st year of follow up, infection-related AF was associated with an increased risk of thromboembolic events compared with non-infection-related AF: adjusted hazard ratio (HR) 1.44 (95% confidence interval (CI) 1.16–1.78) for those initiated on OAC therapy and HR 1.17 (95% CI 1.06–1.28) for those not initiated on OAC therapy. In both groups, OAC therapy was associated with better outcomes than no OAC therapy (HR of thromboembolic events 0.75 (95% CI 0.68–0.83) and HR 0.70 (95% CI 0.63–0.78) for patients with infection-related and non-infection-related AF, respectively). Conclusion: Infection was associated with an increased thromboembolic risk in patients with first-time AF. OAC therapy was associated with a similar risk-reduction in AF patients with and without a concurrent infection.