Table 4.

Associations between Patient Characteristics and EGFR Mutation, Continuous Variables

Variable	EGFR mutation	Negative	EGFR mutation	Positive	t test p value
	N	Mean ± SE	N	Mean ± SE
Pack years*	362	36.7 ± 1.4	26	14.3 ± 4.3	<0.001
Age	428	64.2 ± 0.6	69	64.5 ± 1.3	0.60
Charlson Index	428	5.6 ± 0.1	67	4.9 ± 0.2	0.01
Charlson & age	428	7.6 ± 0.1	67	6.9 ± 0.3	0.03

^*Former or current smokers only