Table 2.

γ-H2AX ratio by host characteristics in cases and controls

	Cases			Controls
	N	Mean(SD)	P a	N	Mean(SD)	P a	P b
Overall	306	1.46(0.14)		306	1.41(0.12)		<0.001
Sex
Male	159	1.47(0.15)		155	1.42(0.13)		<0.001
Female	147	1.45(0.14)	0.620	151	1.40(0.12)	0.237	<0.001
Age
<64c	141	1.48(0.15)		159	1.43(0.14)		<0.001
≥64	165	1.44(0.13)	0.013	147	1.39(0.10)	0.034	<0.001
Smoking status
Never	47	1.46(0.12)	Ref.	128	1.41(0.13)	Ref.	0.002
Former	151	1.45(0.13)		109	1.41(0.12)		0.003
Current	108	1.48(0.16)	0.909d	69	1.40(0.10)	0.742d	0.001
Ever	259	1.46(0.15)	0.352	178	1.41(0.11)	0.751	<0.001
Pack-years
<33e	94	1.46(0.15)		113	1.42(0.11)		0.010
≥33	162	1.46(0.14)	0.811	57	1.39(0.12)	0.336	<0.001
Family history of all cancers
Yes	159	1.46(0.14)		136	1.41(0.13)		<0.001
No	138	1.47(0.15)	0.673	158	1.41(0.11)	0.711	<0.001
Family history of lung cancer
Yes	113	1.46(0.15)		80	1.41(0.14)		0.009
No	192	1.46(0.14)	0.806	221	1.41(0.11)	0.883	<0.001
Dust exposure
Yes	113	1.45(0.14)		39	1.39(0.13)		0.021
No	193	1.46(0.14)	0.156	265	1.41(0.12)	0.483	<0.001
Emphysema
Yes	55	1.48(0.15)		8	1.36(0.07)		0.021
No	249	1.46(0.14)	0.472	296	1.41(0.12)	0.366	<0.001

^aP values for the differences between subgroups by the Wilcoxon rank sum test.

^bP values for the difference between cases and controls.

^cMedian age of the controls.

^dP values for trend derived from the Kruskal-Wallis test.

^eMedian of pack-years among overall ever smokers.