Table 3.

Logistic regression for risk factors on PAL >2 days and >7 days (SE: standard error; df: degree of freedom; OR: odds ratio: CI: confidence interval).

Multiple logistic regression analysis on risk factors of PAL >2 days
Variables	Regression Coefficient	SE	Wald	df	OR	95% CI	P value
Ex-smoker	−0.61	0.42	2.10	1	0.55	0.24–1.24	0.148
Bulla	0.43	0.51	0.73	1	1.54	0.57–4.16	0.394
Asthma	1.11	0.63	3.08	1	3.03	0.88–10.43	0.079
Initial pneumothorax size (%)	0.02	0.12	1.51	1	1.02	0.99–1.04	0.219
Large pneumothorax as defined by BTS guideline	0.15	0.49	0.10	1	1.17	0.44–3.06	0.756
History of ipsilateral pneumothorax	0.87	0.59	2.20	1	2.39	0.76–7.52	0.138
Multiple logistic regression analysis on risk factors of PAL >7 days
Bulla	0.84	0.38	4.91	1	2.32	1.10–4.87	0.027
Albumin (g/L)	−0.06	0.03	4.83	1	0.94	0.89–0.99	0.028
Lung tumour	0.92	0.56	2.76	1	2.52	0.85–7.46	0.096
History of ipsilateral pneumothorax	0.65	0.41	2.55	1	1.91	0.86–4.24	0.111
Large pneumothorax as defined by BTS	−0.46	0.32	2.04	1	0.64	0.34–1.18	0.153