Clinical phenotypes of secondary spontaneous pneumothorax (SSP) in different underlying lung diseases: a retrospective study and literature review on the clinical heterogeneity in this single entity

Background: The clinical outcome of secondary spontaneous pneumothorax (SSP) was mostly evaluated in chronic obstructive pulmonary disease (COPD) or interstitial lung disease (ILD) patients whereas data were limited in non-COPD/ILD-related pneumothorax. This study aimed to describe the clinical outcome of pneumothorax secondary to different pulmonary conditions. Methods: A retrospective observational study was conducted on SSP patients in a Hong Kong hospital. Clinical outcome of pneumothorax secondary to different underlying lung diseases including persistent air leak (PAL), 2-year post-discharge pneumothorax recurrence and all-cause mortality were evaluated. Logistic regression and cox regression analysis were applied for covariates adjustment. Results: 12 days; P=0.02) but similar post-discharge all-cause mortality and recurrence rate at two years compared to non-COPD/ILD-related pneumothorax. Higher proportion of COPD/ILD group was considered unfit for surgical pleurodesis. One-year recurrence rate was lower in asthma (8.3%) and bronchiectasis (0%) patients than other disease groups (15.8-33.3%). Conclusions: Our study demonstrated heterogeneous clinical phenotypes among different lung diseases with poorer outcome in acute chest infection and COPD/ILD population. Differentiation between infective and non-infective, COPD/ILD-related and non-COPD/ILD-related SSP may enable more personalized management.