Abstract
Only very few studies have investigated the influence of eosinophils on the functional progression of COPD. We aimed at retrospectively analyzing the trend of pulmonary function tests over time in patients with COPD according to two baseline blood eosinophil cell count strata (<2% [EOS−] and ≥2% [EOS+]). We used the last 9-year data present in the database of our outpatient clinic and selected only those who had two blood counts that would guarantee the stability of the value of eosinophils and serial spirometry for 4 consecutive years. The analysis of the time course of the spirometric variables analysed showed differences in FEV1 and FVC decline between the subjects of the EOS− group and those of the EOS+ group. The integrated evaluation of our results suggests that the different level of blood eosinophils in the two groups may have influenced independently the time course of the pulmonary function tests and identify two subgroups of subjects with specific disease characteristics: the hyperinflator and the rapid decliner, respectively.
Highlights
The heterogeneity of COPD events stimulates great interest among clinicians and researchers: many aspects of the processes involved in clinical expression and progression of COPD remain to be clarified
We have collected the values of leading spirometry parameters: forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), residual volume (RV), and total lung capacity (TLC), expressed both in absolute terms and as a percentage of the predicted value
Three hundred seventy-eight folders of COPD patients that performed spirometry between January 2009 and December 2011 were analysed of which 157 were ruled out because they did not have a repetition of the measurement of eosinophils, 102 patients were excluded because the eosinophils were not stable over the time, and 84 were excluded because they lacked the repeated spirometry
Summary
The heterogeneity of COPD events stimulates great interest among clinicians and researchers: many aspects of the processes involved in clinical expression and progression of COPD remain to be clarified. The role of eosinophils is between factors that should be investigated, in light of their pathogenetic importance in other airways obstructive syndromes, such as bronchial asthma. Neutrophilic inflammation is commonly reported, a sputum eosinophilia is present in COPD compared with healthy controls and asymptomatic smokers [2, 3]. Sputum eosinophilia has been linked with bronchial hyperreactivity in COPD patients [4]. It was found that during an acute exacerbation, the number of eosinophils in the airways increases 30-fold and that of neutrophils only 3-fold compared with stable COPD [5]. Other authors found no significant differences in the level of eosinophils-related chemokines in elderly patients with COPD with or without atopic symptoms and concluded that the pattern of “allergic inflammation” that is mediated by eosinophils does not play a determining role in the pathogenesis of COPD [6]
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