Impact of anemia on outcomes and resource utilization in patients with myocardial infarction: A national database analysis

Background: Although anemia is common in patients with myocardial infarction (MI), management remains controversial. We quantified the association of anemia with in-hospital outcomes and resource utilization in patients admitted with MI using a large national database. Methods: All hospitalizations with a primary diagnosis code for acute MI in the National Inpatient Sample (NIS) between 2014 and 2018 were identified. Among these hospitalizations, patients with anemia were identified using a secondary diagnosis code. Data on demographic and clinical variables were collected. Outcomes of interest included in-hospital adverse events, length of stay (LOS), and total cost. Multivariable logistic regression and generalized linear models were used to evaluate the relationship between anemia and outcomes. Results: Among 1,113,181 MI hospitalizations, 254,816 (22.8%) included concomitant anemia. Anemic patients were older and more likely to be women. After adjustment for demographics and comorbidities, anemia was associated with higher mortality (7.1 vs. 4.3%; odds ratio 1.09; 95% confidence interval [CI] 1.07-1.12, p < 0.001). Anemia was also associated with a mean of 2.71 days longer LOS (average marginal effects [AME] 2.71; 95% CI 2.68-2.73, p < 0.05), and $ 9703 mean higher total costs (AME $9703, 95% CI $9577-$9829, p < 0.05). Anemic patients who received blood transfusions had higher mortality as compared with those who did not (8.2% vs. 7.0, p < 0.001). Conclusion: In MI patients, anemia was associated with higher in-hospital mortality, adverse events, total cost, and length of stay. Transfusion was associated with increased mortality, and its role in MI requires further research.