Table 1.

Distributions of select characteristics in cases and control subjects

Variables	Cases (n = 470)		Controls (n = 470)		P valuea
	No	(%)	No	(%)
Gender					0.832
Male	324	68.9	328	69.8
Female	146	31.1	142	30.2
Age					0.470
<50	84	17.9	96	20.4
50–59	177	37.7	187	39.8
60–69	129	27.4	111	23.6
≥70	80	17.0	76	16.2
Smoking status					0.321
Non-smoker	265	56.4	281	59.8
Ever-smoker	205	43.6	189	40.2
Pack-year smoked					0.001
<25	75	36.6	96	50.8
≥25	130	63.4	93	49.2

^atwo-side χ2 test