A negative airway reversibility test result does not mean the forced expiratory volume in 1 second limit that can increase after bronchodilator treatment in chronic obstructive pulmonary disease

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation not fully normalized after an inhaled bronchodilator. But even though reversibility test is negative in COPD, some patients’ Forced expiratory volume in 1 second (FEV1) is significantly increased after inhaled bronchodilator therapy in follow-up pulmonary function test (PFT). So, we analyzed the differences between the patients who showed significantly increased pulmonary function and who did not after three months follow-up spirometry.Methods: We reviewed targeted total 328 COPD patients who had been followed up for three months or more and who showed negative airway reversibility test (ART). And we checked age, sex, body mass index, smoking status, current medications, initial and follow-up PFTs etc.Results: The patients had the mean age of 66.0 ± 9.6 years with 246 (76.3%) male. ART results showed negative in total subjects. At follow-up spirometry, the mean FEV1 (L) change (delta FEV1 (L)) was 0.21 ± 0.29, and mean FEV1 (%) change (delta FEV1 (%)) was 9.6 ± 14.1. In ART (%), post-bronchodilator FEV1 (%) was more increased in delta FEV1 (≥12%) than the other group (8.1 ± 6.6 vs. 5.1 ± 5.3, P < 0.001). Current smoker was significantly lower in delta FEV1 (≥12%) group (7.9% vs. 29.2%, P<0.001). And also the subjects with ART (%) positivity was higher in delta FEV1 (≥12%) group (28.6% vs. 12.4%, P<0.001). The patients with increased FEV1 more than or equal to 80%predicted was significantly higher in delta FEV1 (≥12%) group (46.8% vs. 16.3%, P<0.001). But, between post-bronchodilator FEV1 (%) after ART and delta FEV1 (%), Pearson’s correlation showed mild significant correlation (r=0.232, P<0.001).Conclusion: we suggest that negative ART result did not mean the FEV1 limit that could increase after bronchodilator treatment in COPD, and even if ART was negative, delta FEV1 (%) was more increased in follow-up spirometry as post-bronchodilator FEV1 (%) change was higher in initial spirometry.