Exacerbations in the subpopulations and intermediate outcome measures in COPD study (SPIROMICS, NHLBI) are associated with sputum eosinophilia but not blood eosinophilia

Introduction: Eosinophils (Eos) in blood or sputum in subjects with COPD are thought to predict exacerbations and therapeutic response. Objective: To determine whether blood Eos in COPD are valid predictors for sputum Eos and exacerbations, we examined and compared blood and sputum Eos in the SPIROMICS cohort for spirometry, clinical measures, quantitated computed tomography (qCT), and exacerbations. Methods: Comprehensive baseline data on SPIROMICS subjects (broad COPD severity range) included demographics, questionnaires, clinical assessments, qCT, blood and sputum collection. Subjects were stratified by mean blood (N=2499, Results: Subjects stratified by blood Eos showed no significant association with disease severity by GOLD Stage compared to sputum Eos (p=0.0006). Baseline FEV1%pred was lower with blood Eos≥200/mL (p=0.006), but differences were small (66% vs Conclusions: Increased blood Eos did not reliably predict sputum Eos, and unlike sputum eosinophils, showed no association with severity or exacerbations in COPD.