Impact of comorbidities on risk of cardiovascular hospitalization and all-cause mortality among patients with and without atrial fibrillation in an integrated health system

Introduction: Data characterizing the impact of comorbidities on the risk of cardiovascular hospitalization (CVH) and mortality among atrial fibrillation (AF) vs non-AF patients are limited. Methods: This retrospective, comparative cohort study utilized electronic medical record data (MedMining) from 1/01/2005-9/30/210 to characterize the impact of existing and newly occurring comorbidities on risk of CVH and all-cause mortality among AF vs. non-AF patients. Newly diagnosed patients aged ≥40 years with >364 days database enrollment and a qualifying AF diagnosis (≥2 outpatient AF diagnoses within 30 days of each other or ≥1 inpatient diagnosis) were demographically matched to non-AF patients. Results: 3919 AF patients (mean age 72.7±11.5 years) and 3872 non-AF patients (71.1±11.2 years) were included. AF patients had a higher severity of illness (Charlson Comorbidity Index Score ≥4) at baseline vs non-AF patients (29.5% vs 5.8%) and higher prevalence of pre-existing comorbidities (myocardial infarction, heart failure, valvular heart disease, hypertension, diabetes). Baseline comorbidities most highly associated with all-cause mortality risk (rate ratios: 2.4-4.8) in AF patients included stroke, myocardial infarction, cardiac hypertrophy, heart failure, and chronic obstructive pulmonary disease. Among AF patients, 25.3% experienced recurrent AF requiring hospitalization (incidence: 169.6/1000 person-years). The risk of CVH was higher in AF patients (rate ratio=3.4, 95% confidence interval: 3.1-3.7), occurred early, and persisted during the 24-month follow-up observation period (P=0.00182). Conclusions: Newly diagnosed AF patients have a higher prevalence of pre-existing comorbidites, which is associated with an increased risk of all-cause mortality and CVH, most notably AF recurrence requiring hospitalization.