The clinical implications of tests confirming COPD in subjects hospitalized with exacerbations

Background: The diagnosis of COPD in patients hospitalized for AECOPD can be confirmed by spirometry showing obstruction or radiographs showing emphysema. The evidence for COPD is sometimes absent or contradicts this diagnosis. The inaccurate attribution of the exacerbation to COPD can lead to suboptimal care and worse outcome.

Objectives: We determined if the presence of tests that confirm the diagnosis of COPD has any implications on the course of the hospitalization and readmission rate.

Methods: We selected subjects hospitalized between 2012 and 2014 for AECOPD. We divided them into four hierarchical, mutually exclusive groups based on the presence of tests that confirm the diagnosis of COPD: spirometry (COPD_SPIRO), radiology (COPD_RAD), clinical diagnosis (COPD_CLIN), and no COPD by spirometry (NotCOPD). We compared the presentation, hospital course, outcome, and readmission rate between the four groups.

Results: We identified 974 subjects: COPD_SPIRO 22%, COPD_RAD 24%, COPD_CLIN 46% and 7% NotCOPD. The vital signs, use of respiratory support, admission to the MICU, and length of stay were similar between the groups. The age, gender, BMI, presence of comorbidities, and readmission rate were different between the groups. The NotCOPD group had the highest BMI (38 kg/m²), comorbidities, and 30-day all-cause readmission (17%). Logistic regression showed that serum creatinine and presence of any comorbidity were the independent predictors of 30-day all-cause readmission.

Conclusion: COPD was confirmed by spirometry or radiographs in half of the subjects hospitalized for AECOPD. The presence of confirmation did not influence the hospital course. The presence of confirmation was associated with different readmission rate, but was accounted for by the presence of comorbidities.