Reliability and usefulness of spirometry performed during admission for COPD exacerbation

Objectives: Although not currently recommended, spirometry during hospitalization due to exacerbation of chronic obstructive pulmonary disease (COPD) is an opportunity to enhance the diagnosis of this disease. The aim of the present study was to assess the usefulness and reliability of spirometry before hospital discharge, comparing it to measurements obtained during clinical stability. Methods: This prospective longitudinal observational study compares spirometry results before and 8 weeks after discharge in consecutive patients admitted for COPD exacerbation. Concordance between results was assessed by the Kappa index, intraclass correlation coefficient, and Bland-Altman graphs. Results: From an initial population of 179 COPD patients, 100 completed the study (mean age 67.8 years, 83% men, 35% active smokers, FEV1 at clinical stability 40.3%). Forty-nine patients could not complete the study because they did not reach clinical stability. In three patients with obstructive spirometry during admission, the results were normal at follow-up. In the remaining patients, the COPD diagnosis was confirmed at stability with acceptable concordance. In 27 cases, spirometry improved more than 200 mL.No variables were found to be associated with this improvement or to explain it. Conclusions: This study provides information on the role of spirometry prior to hospital discharge in patients admitted for COPD exacerbation, demonstrating that it is a valid and reproducible method, representing an opportunity toimprove COPD diagnosis.