Bronchial Obstruction Reversibility Test in the Assessment of COPD Severity—Controversies

The GOLD and ERS/ATS guidelines recommend the post-bronchodilator FEV₁ (% predicted) to define the severity of chronic obstructive pulmonary disease (COPD). Yet in various publications authors analyze the pre-bronchodilator value or do not clearly state which value was used when the bronchial reversibility test was performed. The guidelines established by the Polish Respiratory Society (PRS) do not specify if performing the reversibility test is necessary to estimate the COPD severity and suggest a reversibility test evaluation which differs from that in the ERS/ ATS and GOLD recommendations. Aim: to assess the changes in the degree of severity of COPD in the classification based upon the pre- and post-bronchodilator FEV₁ and to compare the interpretation of the reversibility test as suggested by GOLD and ATS/ ERS and the PRS. Methods: 145 COPD patients (67F, 78M, mean age 67.5 ± 8.9 yrs) with a negative bronchial obstruction reversibility test (salbutamol 400 μg) were enrolled to the study. For each patient the degree of COPD severity using the pre- and postbronchodilator FEV₁ was established. The pre- and post-bronchodilator classifications were compared. Differences in the interpretation of the reversibility test according to the GOLD and ATS/ ERS and the Polish guidelines were analyzed. Results: In 22 subjects (15.2%) the degree of disease severity changed after salbutamol. The changes were most frequent in the group of severe and very severe COPD (77.3% of changes). In 1 patient (0.7%) post-bronchodilator severity was greater than before salbutamol intake. In 7 patients (4.8%) the post-bronchodilator FEV₁/FVC exceeded 70%, thus excluding the diagnosis of COPD. Of all the 145 negative (according to the ATS/ ERS and GOLD criteria) reversibility tests in 24 cases (16.6%) the test was positive when the criteria recommended by PRS were applied. Conclusions: the bronchial obstruction reversibility test is essential in the diagnosis and assessment of severity of COPD. Despite poor obstruction reversibility in this disease the use of pre-bronchodilator FEV₁ in the assessment of COPD severity may be misleading and is an obstacle in the comparative analysis of studies in the domain of this disease. Differences in the guidelines for the management of COPD may also hinder comparative studies and influence epidemiologic data.