Hospital outcomes associated with new-onset atrial fibrillation during ICU admission: A multicentre competing risks analysis

Purpose New onset atrial fibrillation (NOAF) in critically ill patients has been associated with increased short-term mortality. Analyses that do not take into account the time-varying nature of NOAF can underestimate its association with hospital outcomes. We investigated the prognostic association of NOAF with hospital outcomes using competing risks methods. Materials and methods We undertook a retrospective cohort study in three general adult intensive care units (ICUs) in the UK from June 2008 to December 2015. We excluded patients with known prior atrial fibrillation or an arrhythmia within four hours of ICU admission. To account for the effect of NOAF on the rate of death per unit time and the rate of discharge alive per unit time we calculated subdistribution hazard ratios (SDHRs). Results Of 7541 patients that fulfilled our inclusion criteria, 831 (11.0%) developed NOAF during their ICU admission. NOAF was associated with an increased duration of hospital stay (CSHR 0.68 (95% CI 0.63–0.73)) and an increased rate of in-hospital death per unit time (CSHR 1.57 (95% CI 1.37–1.1.81)). This resulted in a strong prognostic association with dying in hospital (adjusted SDHR 2.04 (1.79–2.32)). NOAF lasting over 30 min was associated with increased hospital mortality. Conclusions Using robust methods we demonstrate a stronger prognostic association between NOAF and hospital outcomes than previously reported.