Predictors of Mortality in Patients with Acute Chest Syndrome: A Comparative Analysis of Patients with and without Asthma
Authors: Guevara Nehemias , Francis-Morel Garry , Perez Esmirna , Zia Maryam 
Published: December 2024

Background: Whileasthma is a known risk factor for Acute Chest Syndrome (ACS), its influence on mortality in patients with Sickle cell disease (SCD) remains unclear. This study, unique in its focus, aims to investigate the role of asthma in influencing mortality, hospital stay, and costs in SCD patients who develop ACS.

Methods: Our study was conducted using a retrospective cohort from the National Inpatient Sample (NIS), spanning 5 years from 2016 to 2020. Patients were carefully divided into two cohorts for comparison: those admitted with ACS and a history of asthma, and those with ACS without a history of asthma. The primary endpoint was all-cause inpatient mortality, and we built a robust multivariate regression model adjusting for confounders. We also thoroughly examined secondary endpoints, including a comparison of length of stay (LOS), hospital, transfusion rates, mechanical ventilation (MV) rates, Continuous Renal Replacement Therapy (CRRT), and rates of hemodialysis (HD) for acute kidney injury (AKI). Our analysis of LOS and total cost was conducted using a multivariate linear regression model adjusted for confounders, ensuring the thoroughness and validity of our results.

Additionally, genotypes, demographics, and common comorbidities were described. Categorical variables required Chi-square (X2), and continuous variables required a Student t-test for hypothesis testing. A two-tailed P-value of &lt;0.05 was considered statistically significant. We utilized the National Inpatient Database (NIS).

Results. A total of 26,280 hospitalizations met the inclusion criteria:5,685 had ACS with a history of asthma, and 20,622 without ACS. Patients with ACS and Asthma were younger (mean age, 28 years vs. 32 years; p &lt;0.001), and females represented a higher proportion (53.03% vs. 47.56%; p=0.940). Patients admitted with ACS and Asthma did not have higher odds of dying than those admitted with ACS without asthma (p = 0.176). The Charlson Comorbidity Index (CCI) was the only predictor of mortality. (aOR 1.52; p &lt; 0.001). ACS with Asthma was a predictive factor for LOS (coefficient -0.65;p = 0.009). Conversely, female patients had a higher likelihood of experiencing a more extended hospital stay (coefficient, 0.61; p = 0.001). Additionally, ACS with Asthma significantly affected the total cost (coefficient: -15,201; p &lt; 0.001), resulting in a lower cost than ACS patients without asthma. Finally, patients with ACS with Asthma did not have higher rates of transfusions, MV, CRRT, or HD due to AKI than those without asthma.

Conclusion: In our retrospective cohort study, we found that asthma was not associated with increased in-hospital mortality among patients admitted for ACS. Despite being a known risk factor for ACS, asthma did not predict higher mortality. Interestingly, patients with ACS and asthma had a shorter length of stay and incurred lower hospital costs compared to those without asthma. The Charlson Comorbidity Index was the primary predictor of mortality. These findings suggest that while asthma complicates the clinical picture of ACS, it does not worsen patient outcomes regarding mortality, hospital stay, or costs.