The primary reason for airway obstruction in sarcoidosis patients is debated. It is speculated that obstruction may be a result of bronchial distortion from lymph nodes, small airways obstruction from granulomas, or fibrosis. Previous studies have attempted to associate CT findings and airflow obstruction; however, these have been limited by small sample size and inconclusive results. Furthermore, population differences preclude comparability across studies. Other studies have stated that smoking history is the main determinant of airway obstruction, and severity of CT findings correlate with airway obstruction only in smokers. The objective of this study was to describe CT findings that are associated with airway obstruction in patients with sarcoidosis and determine the influence of smoking on these parameters.
Clinical and radiographic records of 124 patients with sarcoidosis were reviewed. Pulmonary function tests were used to define airway obstruction (FEV1/FVC<70%). CT scans were assessed blindly for evidence of lymph nodes, nodules, bronchiectasis, thickened bronchovascular bundles, displaced hilum, fibrosis, ground glass, emphysema, pleural changes, and alveolar opacities. CT patterns were compared between patients with and without airway obstruction.
Airflow obstruction was exhibited by 30% of patients and 31% had a smoking history. There was no difference in smoking history between the two groups (28% in obstructed vs. 32% in non-obstructed groups, p=0.63). Airflow obstruction was associated with higher frequencies of nodules, bronchovascular bundle thickening, fibrosis, and displaced hilum. Logistic regression analysis revealed that bronchovascular bundle thickening was the only independent predictor of airway obstruction (p=0.007). Smokers had significantly less bronchovascular bundle thickening than nonsmokers (29% vs. 58%, p=0.003).
Bronchovascular bundle thickening is the only independent predictor of airway obstruction in sarcoidosis patients. Interestingly, smoking was not a determinant of airflow obstruction and suppressed bronchovascular bundle thickening in sarcoidosis patients.
Bronchovascular bundle thickening may be an index of active or progressive disease in sarcoidosis and is inhibited by smoking. Our findings provide a biological correlate for the protective effect of smoking in sarcoidosis as seen in epidemiological studies.
Alicia Gerke, No Financial Disclosure Information; No Product/Research Disclosure Information