Impact of preexisting chronic obstructive pulmonary disease on in-hospital outcomes in first-time acute chest syndrome: A nationwide analysis, 2016–2022

Abstract Background: Acute chest syndrome (ACS) is a severe and potentially life-threatening complication of sickle cell disease (SCD), representing the second most common cause of hospitalization and the leading cause of death among adults with SCD. The incidence of ACS among hospitalized SCD patients is estimated at 25%, with mortality rates ranging from 2–4%. Chronic obstructive pulmonary disease (COPD) affects approximately 5–10% of U.S. adults and is more prevalent in individuals with SCD due to recurrent pulmonary insults. The overlapping clinical features of ACS and COPD—such as cough, hypoxemia, and chest pain—complicate prompt diagnosis and management. While the pathophysiology of ACS is well-characterized, the impact of preexisting COPD on outcomes during a first ACS admission remains poorly understood. To address this knowledge gap, we conducted a nationwide analysis of in-hospital outcomes in patients admitted for a first episode of ACS with preexisting COPD. Methods: A retrospective cohort study was conducted using data from the United States Healthcare Cost and Utilization Project National Inpatient Sample (HCUP-NIS) database from 2016 to 2022. Patients admitted with a primary diagnosis of first-time acute chest syndrome (ACS) and a preexisting diagnosis of chronic obstructive pulmonary disease (COPD) were identified using ICD-10 codes. The primary outcome was in-hospital mortality. Secondary outcomes included length of stay, resource utilization, and need for interventions. Univariate analysis was performed, and variables with p < 0.2 were included in multivariate logistic regression, adjusting for age, gender, race, Charlson Comorbidity Index, hospital location, teaching status, size, region, and insurance status. Statistical significance was set at p < 0.05. Results: Among 36,449 patients admitted with first-time ACS, 2.28% (n = 829) had preexisting COPD. Within this cohort, 63% were female and 96% identified as African American. Patients with both SCD and COPD were significantly older (mean age: 43.8 years, 95% CI: 41.91–45.80) than those without COPD (31.3 years, 95% CI: 31.05–31.61; p < 0.001). Insurance coverage was distributed across Medicaid (46%), Medicare (41%), private insurance (10%), and self-pay. The majority of admissions occurred in the Southern (40%) and Midwestern (29%) regions of the United States. In adjusted analyses, patients with COPD had a non-significant reduction in odds of in-hospital mortality by 77.07% (p = 0.15). This group was associated with a significantly shorter length of stay by an average of 1.24 days (p = 0.012; 95% CI: 0.27–2.21) and a significantly lower mean total hospital charge, with an average difference of $28,064.57 (p < 0.001). There was no difference observed in the odds of red blood cell transfusion (OR = 1.00). Patients with COPD had higher, though not statistically significant, odds of requiring hemodialysis (OR = 3.21; 95% CI: 0.15–68.40; p = 0.45). Additionally, COPD was associated with a significantly lower likelihood of requiring intubation (69.28% reduction in odds; p = 0.043). Conclusion: While COPD is associated with increased respiratory morbidity, these findings paradoxically demonstrate lower in-hospital mortality, shorter length of stay, and reduced need for intubation and hospital charges among patients with SCD admitted for first-time ACS. These results may reflect that patients with a known diagnosis of COPD experience earlier recognition and management of ACS, which leads to better outcomes. Additionally, the results could reflect potential misclassification of COPD in this population or suggest that patients with SCD and coexisting COPD may experience a milder course of the disease. Further prospective studies are warranted to clarify the interaction between COPD and ACS in the SCD population.