Meta-analysis of peripheral blood eosinophils in clinical testing of chronic obstructive pulmonary disease patients

Introduction:
Meta-analysis was used to investigate the relationship between peripheral blood eosinophil (EOS) levels, clinical characteristics, and prognosis in chronic obstructive pulmonary disease (COPD)patients in previous literature.

Aim:
To analyse the correlation between peripheral blood EOS levels and clinical characteristics and prognosis of patients with COPD using meta-analysis.

Material and methods:
In databases such as PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Wan Fang Data, literature related to the clinical characteristics or prognosis of COPD patients with high-level EOS published before July 2023 was searched for meta-analysis.

Results:
Through computer search and screening, 29 articles were ultimately included. The meta-analysis results showed that compared to conventional EOS levels, COPD patients with high EOS levels had a lower proportion of GOLD III–IV grade patients (OR = 00.78, 95% CI (0.68, 0.88), p < 0.001), lower CAT scores (OR = –1.01, 95% CI (–1.75, –0.28), p = 0.007), shorter hospital stay (OR = –1.33, 95% CI (–1.52, –1.14), p < 0.001), and lower mortality rate (OR = 0.53, 95% CI (0.42, 0.66), p < 0.001). The readmission rate was low (OR = 0.40, 95% CI (0.33, 0.48), p < 0.001), and there was no statistically significant difference in FEV1%pred (OR = –0.55, 95% CI (–1.33, 0.23), p = 0.17), higher FEV1/FVC values (OR = –0.45, 95% CI (–1.08, 0.18), p = 0.160), and mechanical ventilation usage rate (OR = 0.89, 95% CI (0.65, 1.21), p = 0.450) among COPD patients with different EOS levels.

Conclusions:
The levels of peripheral blood EOS in COPD patients are related to lung function, respiratory symptoms, etc.; Moreover, COPD patients with high-level EOS have shorter hospital stays, lower mortality and readmission rates. Therefore, ESO can be used as an auxiliary indicator for clinical symptom diagnosis of COPD patients and as an auxiliary indicator for predicting prognosis.