How Common is Airflow Limitation in Patients with Emphysema on Computerized Tomography of the Chest?
Chest. 2014 Dec 24;
Authors: Lutchmedial SM, Creed WG, Moore AJ, Walsh RR, Gentchos GE, Kaminsky DA
Background: COPD has traditionally been defined by the presence of irreversible airflow limitation on spirometry using either the GOLD or ATS/ERS criteria (lower limit of normal, LLN). We have observed that some patients with clinical COPD and emphysema on chest computerized tomography (CT) have no obstruction on spirometry. The purpose of this study was to assess the prevalence of obstruction by GOLD and LLN criteria in patients with emphysema on CT and determine which radiographic criteria were associated with a clinical diagnosis of COPD.
Methods: We retrospectively analyzed the clinical records and spirometry of all patients who had radiographically defined emphysema on chest CT scans completed at the University of Vermont in 2011. We compared spirometric criteria and CT factors with the presence of clinical COPD based on chart review.
Results: We identified 274 patients with CT defined emphysema. GOLD detected obstruction in 228 (83%) and LLN in 206 (75%) of patients. However, GOLD failed to correctly identify 19 (6.9%) patients and LLN 38 (13.9%) patients (average 10.4%) who had radiographic emphysema and a clinical diagnosis of COPD. Obese patients had a lower prevalence of obstruction whether classified by LLN or by GOLD. Among patients with spirometric obstruction, there were greater degrees of emphysema, and more severely increased airway wall thickness. Factors that were independently associated with clinical COPD were lower FVC % predicted, lower FEV1/FVC ratio and increasing airway wall thickness.
Conclusions: Spirometry missed 10.4% of patients with clinical COPD who have significant emphysema on chest CT.
PMID: 25539080 [PubMed - as supplied by publisher]