Atrial Fibrillation Does Not Negatively Impact the Outcomes of Patients Admitted for Hyperthyroidism: Analysis of the National Inpatient Sample

Introduction: Hyperthyroidism is a well-known risk factor for the development of atrial fibrillation(AF), but the outcomes hyperthyroidism in patients with atrial fibrillation is unclear. This study aims to compare the outcomes of patients primarily admitted for hyperthyroidism with and without a secondary diagnosis of AF. Methods: Data were abstracted from the National Inpatient Sample (NIS) 2016 and 2017 Database. NIS is the largest inpatient hospitalization database in the United States. The NIS was searched for hospitalizations with a principal diagnosis of hyperthyroidism with and without AF as secondary diagnosis using ICD-10 codes. Hospitalizations for adult patients (age≥ 18 years) from the above groups were identified. The primary outcome was inpatient mortality. Hospital length of stay (LOS), total hospital charges, cerebrovascular accident and acute respiratory failure were secondary outcomes of interest. Multivariate logistic and linear regression analysis was used accordingly to adjust for confounders. Results: There were over 71 million discharges included in the combined 2016 and 2017 NIS database. 17,705 hospitalizations were for adult patients who had a principal ICD-10 code for hyperthyroidism. 4,165 (23%) of these hospitalizations had co-existing AF. AF group were older (57 vs 44 years, P < 0.0001) and had less females (65% vs 78%, P < 0.0001). Hospitalizations for Hyperthyroidism with AF had similar inpatient mortality (0.96% vs 0.33%, AOR: 1.7, 95% CI 0.58-5.14, P=0.324) with longer LOS (5.1 vs 3.2 days, P=0.000), increased total hospital charges ($51,904 vs $34,471, P=0.002), increased odds of cerebrovascular accident (0.8% vs 0.1%, AOR: 5.01, 95% CI 1.1-22.2, P<0.034) and increased odds of acute respiratory failure(4.4% vs 1.3%, AOR: 3.01, 95% CI 1.8-5.0, P<0.000) compared to those without AF. Conclusions: Patients admitted primarily for hyperthyroidism with co-existing AF had similar inpatient mortality but with longer LOS, increased total hospital charges, increased likelihood of having cerebrovascular accident and acute respiratory failure when compared to those without AF.