Temporal Trends in Comorbidity Burden and Impact on Prognosis in Patients With Acute Coronary Syndrome Using the Elixhauser Comorbidity Index Score

Abstract

Despite current evidence, little is known about the impact of comorbidity burden on invasive management strategies and clinical outcomes in the context of acute coronary syndrome (ACS). All ACS hospitalizations between 2004 and 2014 from the National Inpatient Sample were included, stratified by Elixhauser Comorbidity Score (ECS) and number of Elixhauser Comorbidities (NEC) to compare the receipt of invasive management and clinical outcomes between different ECS and NEC classes to the lowest class of either measure. A total of 6,613,623 records with ACS were included in the analysis. Overall comorbidity burden increased over the 11-year period, with higher comorbidity classes (ECS ≥ 14 and NEC ≥ 5) increasing from 2.1% to 4.6% and 4% to 16%, respectively. Higher ECS and NEC classes negatively correlated with the rates of utilization of coronary angiography (CA) and percutaneous coronary intervention (PCI) (ECS ≥14 vs <0: CA: 38.2% vs 69.3%, PCI: 18.6% vs 45.3%; NEC ≥5 vs 0: CA: 49.3% vs 73.4%, PCI: 24.4% vs 57.4%). Overall, higher ECS and NEC classes were independently associated with significantly increased odds of all complications, including major acute cardiovascular and cerebrovascular events, mortality, stroke and bleeding. In conclusion, among patients hospitalized for ACS, a higher comorbidity number or severity is associated with lower rates of receipt of CA and PCI, but not coronary artery bypass grafting, and worse clinical outcomes. Comorbidity burden assessment using ECS can help stratify patient groups at greatest risk of adverse outcomes in which invasive management is currently underutilized.