The influence of Elixhauser comorbidity index on percutaneous coronary intervention outcomes

BACKGROUND: Clinical outcomes with respect to the evolution of comorbidity burden in national cohorts of patients undergoing PCI have not been reported. OBJECTIVES: We sought to explore the association between comorbidity burden and periprocedural outcomes in patients treated with PCI in the National Inpatient Sample. METHODS: 6,601,526 PCI procedures were identified between 2004 and 2014 and comorbidities were defined by the Elixhauser classification system (ECS) consisting of 30 comorbidity measures. Endpoints included in-hospital mortality, periprocedural complications, length of stay and cost. Patients were classified based on their ECS in five categories (ECS I < 0, ECS II = 0, ECS III = 1-5, ECS IV = 6-13, and ECS V ≥ 14). RESULTS: Patients with a score over 13 had a fivefold increase in the odds of mortality (OR: 5.13, 95% CI: 4.76-5.54), major bleeding (OR: 11.46, 95% CI: 10.66-12.33) and doubled the hospitalization costs ($31,452 vs $17.566). CONCLUSIONS: Our study of over six million PCI procedures demonstrates that patients with the greatest comorbid burden (as defined by an ECS of >13) have a fivefold increase risk of in-hospital mortality, a fourfold increase in in-hospital periprocedural complications and an 11-fold increase in major bleeding events once differences in baseline patient characteristics are adjusted for. In addition, ECS significantly impacts the length of stay and doubles the healthcare costs. Comorbid burden is an important predictor of poor outcomes after PCI and should be considered as part of the decision-making processes in patients undergoing PCI.