Risk factors related to the recurrence of pneumothorax in patients with emphysema

Background: Pneumothorax refers to the abnormal presence of air in the thoracic cavity. Pulmonary emphysema (PE) is often detected during computed tomography (CT), one of the radiological investigations used to diagnose pneumothorax and devise treatment plans in former or current smokers who present with pneumothorax. However, there are few reports that describe the recurrence rate and risk factors associated with recurrence in patients with PE and pneumothorax. Methods: This study retrospectively cross-sectional analyzed the medical records of 164 patients diagnosed with their first episode of secondary spontaneous pneumothorax and admitted to a tertiary care hospital, between March 2013 and February 2019. The CT scans of 98 patients revealed PE, and 49 patients of those underwent pulmonary function tests (PFTs) after the resolution of pneumothorax. Risk factors for recurrence were analyzed using Cox proportional hazard regression. Results: All the subjects were male and former or current smokers, with a median age of 72 years. Thirty-seven (75.5%) patients were treated with tube thoracostomy alone, whereas 12 (24.5%) patients underwent chemical pleurodesis via chest tube or video-assisted thoracoscopic surgery. After recovery from pneumothorax, these patients underwent PFT within a median time period of 5.8 months. Median forced vital capacity and forced expiratory volume in 1 second (FEV1) were 3.02 L (91% predicted) and 1.58 L (67% predicted), respectively. In the current study, the recurrence rate of pneumothorax was observed to be 30.6%, within a median time period of 12.4 months. In multivariable-adjusted analysis, decreased FEV1 was observed to be significantly higher in the patients who exhibited recurrence of pneumothorax than in those who did not (adjusted hazard ratio, 0.408; P=0.025). Conclusions: In patients with PE and pneumothorax, PFT, performed after recovery, could be a useful test for predicting the recurrence of pneumothorax.