Eosinophilia and clinical outcome of chronic obstructive pulmonary disease: a meta-analysis

Abstract

Numerous studies have investigated the association between eosinophilia and clinical outcome of patients with chronic obstructive pulmonary disease (COPD) but the evidence is conflicting. We conducted a pooled analysis of outcome measures comparing eosinophilic and non-eosinophilic COPD patients. We searched articles indexed in four databases using Medical Subject Heading or Title and Abstract words including COAD, COPD, eosinophil, eosinophilia, eosinopenia from inception to December 2016. Observational studies and randomized controlled trials with parallel groups comparing COPD patients with and without eosinophilia were included. Comparing to the non-eosinophilic group, those with eosinophilic COPD had a similar risk for exacerbation in 12 months [Odds ratio = 1.07, 95% confidence interval (CI) 0.86-1.32, P = 0.55] and in-hospital mortality [OR = 0.52, 95% CI 0.25-1.07]. Eosinophilia was associated with reduced length of hospital stay (P = 0.04). Subsequent to therapeutic interventions, eosinophilic outpatients performed better in pulmonary function tests [Mean Difference = 1.64, 95% CI 0.05-3.23, P < 0.001]. Inclusion of hospitalized patients nullified the effect. Improvement of quality of life was observed in eosinophilic subjects [Standardized Mean Difference = 1.83, 95% CI 0.02-3.64, P = 0.05], independent of hospitalization status. In conclusion, blood eosinophilia may be predictive of favorable response to steroidal and bronchodilator therapies in patients with stable COPD.

Figure 1

Flow diagram of literature search and selection of studies.

Figure 2

Forest plots of studies comparing the risk for exacerbation in 12 months in COPD patients with or without eosinophilia. Vedel-Krogh (2015) subgroup A, clinical COPD; Vedel-Krogh (2015) subgroup B, COPD cohort in general population; Pavord (2016) subgroup A, COPD patients on fluticasone propionate and salmeterol; Pavord (2016) subgroup B, COPD patients on fluticasone propionate.

Figure 3

Forest plots of studies comparing the risk for in-hospital mortality in COPD patients with or without eosinophilia.

Figure 4

Forest plots of studies comparing the mean difference of the length of hospital stay.

Figure 5

Forest plots of studies comparing the mean difference of the change of FEV1 in COPD patients after therapy. Bafadhel (2012) subgroup A, clinical outcomes in 2 weeks after therapy. Bafadhel (2012) subgroup B, clinical outcomes in 6 weeks after therapy.

Figure 6

Forest plots of studies comparing the mean difference of the change of % FEV1 predicted in COPD patients after therapy. Bafadhel (2012) subgroup A, clinical outcomes in 2 weeks after therapy. Bafadhel (2012) subgroup B, clinical outcomes in 6 weeks after therapy. Pavord (2016) subgroup A, COPD patients on fluticasone propionate and salmeterol; Pavord (2016) subgroup B, COPD patients on fluticasone propionate; Pavord (2016) subgroup C, COPD patients on salmeterol.

Figure 7

Forest plots of studies comparing the standardized mean difference of the change of quality of life scores in COPD patients after therapy. Pavord (2016) subgroup A, COPD patients on fluticasone propionate and salmeterol.