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

The aim of this study was to compare long-term thromboembolic risk in infection-related and non-infection-related atrial fibrillation (AF).

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.

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).

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.