Blood Eosinophils and Mortality in Patients With Acute Respiratory Distress Syndrome: A Propensity Score Matching Analysis

Background: The effect of blood eosinophils on mortality in acute respiratory distress syndrome (ARDS) patients and whether this effect is impacted by corticosteroids are unclear. This study explored the relationship between blood eosinophils and 28-day mortality in ARDS patients and investigated whether the relationship varied according to corticosteroid use. Methods: : The Medical Information Mart for Intensive Care III database was employed to extract data. Patients with ARDS who were 16 years or older, used mechanical ventilation during the ICU stay and stayed in the ICU for at least 48 consecutive hours were screened for inclusion. Cox regression models using the stepwise backward method and propensity score matching (PSM) were employed to assess the relationship between blood eosinophil counts and 28-day mortality. Result: A total of 3372 patients were included, and the 28-day mortality rate was 24.23% (817/3372). The crude 28-day mortality was significantly lower in patients with eosinophil count ≥2% (105/574 vs. 712/2798, p< 0.001) than in those with eosinophil count <2%. In the Cox regression model, the eosinophil count ≥2% showed a significant association with decreased 28-day mortality (hazard ratio (HR) 0.761; 95% confidence interval (CI) =0.620-0.935, p=0.009). In a subgroup analysis, we detected an interactive effect of eosinophils and corticosteroids use (p value for interaction, p=0.006). In the corticosteroid non-use subgroup, eosinophil counts ≥2% were significantly related to decreased 28-day mortality (HR=0.730, 95% CI =0.577-0.923), but the result was non-significant in the corticosteroid non-use subgroup model (p=0.231). A total of 574 well-matched pairs were obtained by a 1:1 matching algorithm after PSM. The 28-day mortality remained significantly lower in the eosinophil count ≥2% group than in the eosinophil count <2% group (105/574 vs 136/574, p=0.025). Conclusions: : Higher eosinophil counts are related to lower 28-day mortality in ARDS patients, and this relationship can be counteracted by using corticosteroids.