Table 3. Factors affecting recurrence.

Variables	Univariate				Multivariate
	OR	95% CI	P		OR	95% CI	P
Age	1.00	0.97–1.03	0.83
Gender†	0.28	0.07–0.99	0.05		0.71	0.16–3.05	0.64
Previous history of
COPD/ILD	1.79	0.72–4.46	0.21
Pneumothorax	2.01	0.83–5.28	0.12
Operation	0.42	0.05–3.64	0.43
Smoking
Current	0.66	0.26–1.66	0.38
Quit	1.95	0.85–4.51	0.12
Radiologic findings
Bullae/blebs†	5.23	2.14–12.8	<0.01		5.57	2.06–15.1	<0.01
Bronchiectasis	2.32	0.71–7.51	0.16
Emphysema†	4.78	1.86–12.3	<0.01		3.83	1.34–10.9	0.01
ILD/IPF	1.9	0.40–9.00	0.42
Sequelae of tuberculosis	1.3	0.51–3.27	0.59
Management
Observation	0.88	0.09–8.72	0.91
Chest tube drainage	0.55	0.09–3.47	0.53
Chemical pleurodesis	0.91	0.33–2.57	0.87
Operation†	0.14	0.02–1.09	0.06		0.11	0.01–0.93	0.04

^†, these factors were included in the multivariate analysis. OR, odds ratio; CI, confidence interval; COPD, chronic obstructive pulmonary disorder; ILD, interstitial lung disease; IPF, idiopathic pulmonary fibrosis.