Impact of obesity on inpatient outcomes in patients hospitalized with acute chest syndrome

Abstract Background: Acute chest syndrome (ACS) is a serious and potentially fatal complication of sickle cell disease. Obesity, a growing public health concern, may influence outcomes in ACS due to its impact on respiratory physiology and inflammation. However, limited data exist on the relationship between obesity and inpatient outcomes in this population. This study aimed to evaluate the impact of obesity on mortality, length of stay (LOS), hospital charges, and respiratory support needs in ACS hospitalizations. Methods: We conducted a retrospective analysis of adult inpatient discharges from the National Inpatient Sample (NIS) between 2016 and 2022. Patients hospitalized with acute chest syndrome were identified using ICD-10-CM codes. Obesity was identified using secondary diagnostic codes. National estimates were calculated using NIS-supplied survey weights. Outcomes included inpatient mortality, LOS, total hospital charges, and use of mechanical and non-invasive ventilation. Multivariable logistic regression was used to assess mortality and ventilation outcomes, while linear regression was used for LOS and cost. All models were adjusted for age, sex, race, primary payer, hospital characteristics, and comorbidities using the Charlson Comorbidity Index (CCI). A p-value < 0.05 was considered statistically significant. Results: Among 49,189 hospitalizations with ACS, 6.4% (n=3,150) had a diagnosis of obesity. Obese patients were more often female (67.5% vs. 32.4%, p < 0.0001) and had a higher mean age (34 vs. 31.9 years, p < 0.0001). Racial distribution among obese patients included 92.5% African American, 4.8% Hispanic, and 0.9% White (p = 0.5). Overall inpatient mortality was 1.6%. Mortality among obese ACS patients was 2.1% compared to 1.6% in non-obese patients (p = 0.3); however, after adjustment, obesity was not significantly associated with mortality (aOR 1.01, p = 0.9). Average LOS was longer in obese patients (8.6 vs. 7.4 days), but adjusted analysis showed a non-significant decrease in LOS by 0.21 days (p = 0.24). Obese patients were more likely to require mechanical ventilation (5% vs. 4%, p = 0.0007) and non-invasive ventilation (7.2% vs. 2.4%, p < 0.0001). Adjusted odds of requiring mechanical ventilation were 44% higher in obese patients, and odds of requiring non-invasive ventilation were 300% higher compared to non-obese patients.Conclusion: While obesity was not associated with increased inpatient mortality or prolonged hospitalization in patients with acute chest syndrome, it was significantly associated with greater use of mechanical and non-invasive ventilation. These findings suggest that obesity contributes to increased respiratory support needs in ACS, potentially reflecting underlying physiologic vulnerability. Further studies are warranted to explore targeted interventions in this subgroup.