Table 4. Multivariate analysis of occult pneumothorax risk factor in supine chest radiography in blunt trauma patients.

Chest radiography	All patient			AIS ≥3
	P value	OR (95% CI)		P value	OR (95% CI)
Rib fracture	N/S	N/S		0.002	1.544 (1.173–2.033)
Lung contusion	0.005	1.440 (1.115–1.860)		0.001	1.580 (1.208–2.066)
Subcutaneous emphysema	<0.001	25.883 (13.155–50.928)		<0.001	24.930 (12.612–49.282)

AIS, abbreviated injury score; OR, odds ratio; CI, confidence interval; N/S, not significant.