The role of pre-existing iron deficiency anemia in hospitalizations for cardiogenic shock

Abstract Background: Iron deficiency anemia (IDA) is one of the most common hematologic disorders and has been increasingly recognized as a contributor to impaired cardiovascular health. IDA can lead to reduced oxygen-carrying capacity, increased cardiac workload, and myocardial remodeling, all of which may predispose patients to heart failure and hemodynamic instability. In patients with established cardiac disease, IDA has been associated with worse functional status and poorer outcomes. However, the impact of IDA on the clinical trajectory of patients presenting with cardiogenic shock (CS)—a critical condition of severe cardiac dysfunction and end-organ hypoperfusion—remains unclear. This study aimed to evaluate inpatient outcomes among patients hospitalized for CS, comparing those with and without a documented history of IDA. Methods: We performed a weighted retrospective analysis using the National Inpatient Sample (2016–2022), identifying adult hospitalizations with a primary diagnosis of cardiogenic shock (ICD-10-CM: R57.0). Patients were stratified based on the presence or absence of a documented history of iron deficiency anemia (ICD-10-CM: D50.x). Demographics and inpatient outcomes were compared using multivariable logistic regression models adjusted for age, sex, and race. All analyses were conducted using STATA version 19.0, with statistical significance defined as a two-sided p-value < 0.05. Results: Among 750 weighted hospitalizations for cardiogenic shock, 345 (44.2%) were female and 62.0% identified as White, with a mean age of 64.9 years (±1.16). A history of iron deficiency anemia (IDA) was associated with significantly lower in-hospital mortality (adjusted OR 0.35, 95% CI: 0.23–0.52; p < 0.001), indicating a 65% reduction in the odds of death compared to patients without IDA. IDA was also associated with a longer hospital stay, with an adjusted increase of 1.85 days (95% CI: 0.06–3.65; p = 0.043). Clinical complications including cardiac arrest, arrhythmias, AKI, encephalopathy, and thromboembolic events did not differ significantly by IDA status. Patients with IDA had significantly higher odds of receiving PRBC transfusion (OR 2.54, p < 0.001) and lower odds of requiring mechanical ventilation (OR 0.54, p = 0.001).Conclusion: In this national analysis, a history of iron deficiency anemia was associated with significantly lower in-hospital mortality and increased odds of transfusion among patients hospitalized for cardiogenic shock. IDA was also linked to a modest increase in length of stay but not significantly associated with major inpatient complications. These findings suggest that while IDA may reflect a more chronic or stable disease phenotype in this setting, it does not appear to worsen inpatient outcomes. Nonetheless, results should be interpreted in the context of limitations inherent to administrative data, including reliance on coding accuracy, absence of laboratory and disease-specific variables such as hemoglobin levels or iron studies, and lack of post-discharge outcomes.