Admission Eosinopenia and Clinical Severity in Patients Hospitalised with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: An Observational Study

Abstract

 Background: Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are heterogeneous in severity and may require early identification of patients at greater clinical risk. Peripheral blood eosinopenia is an inexpensive and routinely available laboratory finding that has been proposed as a marker of acute systemic stress. However, its relationship with the overall clinical severity of AECOPD remains incompletely characterised. Objective: To evaluate the prevalence of admission eosinopenia and the relationship between admission eosinophil count and predefined clinical severity strata among patients hospitalised with AECOPD. Methods: A hospital-based observational study included 185 patients aged 18–65 years admitted with AECOPD at a tertiary care teaching hospital. Complete blood count with differential was obtained at admission. Eosinopenia was defined as an absolute eosinophil count <0.05×10⁹/L. Patients were classified into three predefined ascending clinical severity strata used in the parent study. Admission eosinophil and total leukocyte counts were compared across these strata. Results: Among 185 patients, 80 (43.2%) had admission eosinopenia. The three severity strata comprised 70 patients in the lowest-risk group, 90 in the intermediate group and 25 in the highest-risk group. Mean eosinophil count progressively decreased across increasing severity strata from 0.12±0.05×10⁹/L to 0.08±0.04×10⁹/L and 0.04±0.02×10⁹/L, respectively (p<0.001). Conversely, mean total leukocyte count increased from 8.0±1.5×10⁹/L to 9.2±2.0×10⁹/L and 10.0±2.5×10⁹/L, respectively (p = 0.01). Conclusion: Admission eosinophil count showed a significant inverse relationship with increasing clinical severity in this cohort of patients hospitalised with AECOPD. Eosinopenia is a readily available laboratory finding that may serve as a marker of overall clinical severity. Because eosinopenia contributed to the composite severity classification used in the parent study, these findings should be interpreted as an association with severity rather than evidence of an independent causal or prognostic effect.