Elevated blood eosinophils on admission for a severe exacerbation of COPD is not a predictor for survival

Background: In patients hospitalised for an exacerbation of COPD (severe AECOPD), elevated blood eosinophil count was associated with a shortened length of stay. Less is known about its association with survival.

Aims and objectives: The aim of this study was to evaluate the association of elevated blood eosinophil count at admission for a severe AECOPD with all-cause mortality.

Methods: 450 patients of the COMIC cohort study who were admitted for a severe AECOPD were divided in normal or elevated blood eosinophil count, defined as eosinophils ≥2% of the total leukocyte count on day of admission. Outcome parameter was all-cause mortality. Minimum follow-up was 3 years.

Results: Elevated blood eosinophil count (N=97) was associated with a significantly lower risk for all-cause mortality in univariate analysis (Figure 1; logrank p=0.004) (HR 1.53; 95%CI 1.15-2.04).

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Patients with elevated blood eosinophil count were younger than patients with normal blood eosinophil count (66.3 (SD 10.4) versus 70.6 (SD 9.6) years, respectively (p<0.001)). Corrected for age this association disappeared (adjusted Hazard Ratio of 1.25; 95% CI, 0.93-1.66).

Conclusion: The strong association of elevated blood eosinophils on admission for a severe AECOPD with lower risk for mortality in univariate analysis disappeared after correction for age. The association of age with eosinophil count needs further investigation.