Post-bronchodilator Reversibility of FEV1 and Eosinophilic Airway Inflammation in COPD

Abstract

IntroductionThe relationship between bronchodilator responsiveness and eosinophilic airway inflammation has not been well documented in COPD. It has been investigated in this retrospective study. This issue has grown in importance due to increasing interest in the asthma-COPD overlap syndrome. Methods264 stable COPD patients with no past history of asthma were retrospectively analyzed. Correlation analyses between FEV1 reversibility and sputum eosinophil levels were conducted. Sputum eosinophil levels were dichotomized using FEV1 reversibility cut-off points (>0.4L and >15% vs. >0.2L and >12%) and compared. The effectiveness of FEV1 reversibility to predict sputum eosinophilia (>3%) was analyzed with a logistic regression and a ROC analysis. Results82 (31.1%) patients with higher FEV1 reversibility values (0.14 vs. 0.11L, P=.01) presented sputum eosinophilia. FEV1 reversibility was weakly correlated with the sputum eosinophil level (r=0.162, P=.008). Patients with FEV1>0.4L and >15% increment had higher sputum eosinophil levels (6.11 vs. 1.02%, P=.049) whereas the level did not differ when dichotomized by FEV1 increment >0.2L and >12%. Very positive FEV1 reversibility (>0.4L and >15%) predicted sputum eosinophilia after adjustment forage, baseline FEV1 and FVC (OR: 4.262, P=.029). In the ROC analysis, the AUC was 0.58 (P=.034), and FEV1 increment>0.4L and >15% had a positive predictive value of 63.6% and an overall accuracy of 70.1%. ConclusionsFEV1 reversibility was weakly correlated with sputum eosinophil levels in COPD. Positive FEV1 reversibility (>0.4L and >15%) is moderately successful in predicting sputum eosinophilia (>3%).