Risk factors for pneumothorax after treatment with endobronchial valves; a retrospective cohort study

<bold>Background:</bold> Pneumothorax (PTX) is the most prevalent and serious adverse event associated with endobronchial valve (EBV) treatment in chronic obstructive pulmonary disease (COPD). No previous cohort studies have been performed in patients with high fissure integrity. This study aimed to compare pre-operative characteristics and 30-day outcome in patients with COPD with and without pneumothorax. <bold>Method:</bold> This retrospective cohort study included patients treated with EBV between 2017-2023 at Aarhus University Hospital in Denmark. Data used were retrieved from medical records. <bold>Results:</bold> A total of 113 patients were included, of whom 25 (22.1%) had PTX. The median time to drain treatment was 6 hours (range 1-104) and median drain treatment duration was 13 days (range 2-82). The risk of PTX was significantly higher when EBV treatment was performed in the upper lobes compared to the lower lobes (adjusted RR 5.28 [CI 1.39; 14.49]). The frequency of PTX was 21/55 (38%) and 4/58 (7.0%) in the upper and lower lobes, respectively. Patients with PTX had a higher TLC(146.6% vs. 136.3%, p = 0.0434) compared to non-PTX patients; there were no differences in age, BMI, FEV1, FVC, RV, target lobe volume, ipsilateral lobe volume, contralateral lung volume and 6-minute walking test. The risk ratio of pneumonia during the first 30 postoperative days was 2.78 (95 % CI 1.67;4.63), 60% in PTX patients and 21.5% in non-PTX patients. <bold>Conclusions:</bold> Pneumothorax was more prevalent when EBV treatment was performed in the upper lobes. leading to prolonged hospital admission and risk of hospital-acquired pneumonia.