Background: Bronchiectasis is known to be associated with COPD. We studied which degree of radiological alterations was associated with clinical signs of bronchiectasis in COPD. Methods: Visit 4 data (GOLD grades 1-4) of the COSYCONET cohort was analysed. Chest CT scans were evaluated for bronchiectasis in 6 lobes using a 3-point scale (0-2), resulting in a total score of 0-12. We also included data from disease-specific questionnaires, medication, and lung function. Results: 1176 patients were included (mean age 67.3y, 61.1% males), among them 38 (3.2%) with patient-reported physicians’ diagnosis of bronchiectasis and 76 (6.5%) with alpha1-antitrypsin deficiency (AA1D). 429 patients had CT scans, with any signs of bronchiectasis in 46.6%, less than 50% bronchiectasis in ≤2 lobes in 18.6%, in 3-4 lobes in 10.0%, in 5-6 lobes in 15.9%, and more than 50% bronchiectasis in at least 1 lobe in 2.1%. Scores ≥4 were linked to elevated FRC/RV. Links to sputum production, composition (n=105) or inflammatory indices were borderline or absent. Triple therapy was associated with symptoms, but not radiological signs of bronchiectasis. The clinical diagnosis of bronchiectasis correlated with phlegm and cough and with radiological scores of at least 3, optimally ≥5. AA1D was associated with radiological signs of bronchiectasis and only borderline with the clinical diagnosis. Conclusion: Clinical diagnosis and radiological signs of bronchiectasis showed only weak correlations in COPD patients. For a significant correspondence to symptoms and diagnosis, a threshold CT score implying radiological alterations in several lobes was needed, which was about one third of the maximum score.
