Table 4.

Superior vena cava (SVC) and left innominate vein comparison (chi-square test) on contrast-enhanced CT between patients with pleural effusion and a random matched control group without effusion

		Total patients ALL	Patients with pleural effusion	Matched cohort of patients without pleural effusion	P-value
n		425	217	208
Stage	I	7	3	4	0.96
	II	298	152	146
	III	66	35	31
	IV	54	27	27
SVC pre-treatment	Normal	93	48	45	0.14
	Slight compressiona	96	48	48
	Compressionb	172	83	41
	Obliteratedc			48
SVC post-treatment	Normal	355	179	176	0.14
	Slight compressiona	7	2	5
	Compressionb	5	5	0
	Obliteratedc	2	1	1
Left innominate pre-treatment	Normal	73	40	33	0.42
	Slight compressiona	79	88	39
	Compressionb	187	88	99
	Obliteratedc	31	20	11
Left innominate post-treatment	Normal	318	157	161	0.06
	Slight compressiona	21	8	13
	Compressionb	19	14	5
	Obliteratedc	10	8	2

^aSlight compression = <50% narrowing of vessel

^bCompression = >50% narrowing

^cObliterated = total compromise of vessel lumen

The significance level of P-value is 0.05