Table 2.

Summary of the results of Cox proportional hazards regression analysis

Covariates	HR (95% CI)	P-value
Univariate analysis
Female sex	2.30 (0.41–13.0)	<0.001
Young age (under 25 years)	3.93 (0.81–19.2)	0.09
Non-smoker	4.37 (0.90–21.3)	<0.001
Bilateral PSP	5.18 (1.41–19.1)	<0.001
Apical lung blebs	9.00 (2.18–37.1)	<0.001
Reticulated trabecula-like structure	16.2 (3.22–82.0)	<0.001
Multivariate analysis
Reticulated trabecula-like structure	16.2 (3.22–82.0)	<0.001

HR: hazard ratio; CI: confidence interval; PSP: primary spontaneous pneumothorax