Correlation between sputum and blood eosinophils in asthmatic and COPD patients with comorbidities.

Abstract

Introduction: Airway eosinophilic inflammation can be found in asthmatic and COPD patients. Blood eosinophil count is deemed good surrogate marker of sputum eosinophilic inflammation; however, controversial data have been published both in asthmatic and COPD populations. Methods: Sputum was induced in stable patients with asthma or COPD with hypertonic saline solution. Blood eosinophils were measured. Frequency of comorbidities was recorded. Results: Sputum and blood eosinophils were correlated both in asthma and in COPD. Inhaled steroid treatment and history of previous exacerbations seem not to affect blood and sputum eosinophil correlation. The most frequent comorbidities were hypertension, obesity and OSAS for the two groups; rhinitis and GERD for asthma, and cardiac diseases for COPD. In asthmatic patients with rhinitis and in COPD patients with atrial fibrillation or ischemic heart disease, correlations were not statistically significant. Asthmatic patients with history of GERD (n= 12) showed lower median (IQR) sputum eosinophils than those without (1.25% (0.1 - 3.35) VS. 5.8% (1.7-30.7), respectively; P= 0.01). Conclusion: Blood eosinophils correlated with sputum eosinophils in asthmatic and COPD patients. Among the most frequent reported comorbidities, cardiac diseases in COPD, and rhinitis and GERD in asthma can reduce this correlation. These preliminary data need to be confirmed by studies with larger sample size.