Table 2.

Characteristics of study participants stratified by sex

Characteristic	Total, n (%) 31,394 (100)	Male, n (%) 17,490 (55.7)	Female, n (%) 13,904 (44.3)	P value
Age range				＜0.001
~ 39	5127 (16.3)	3163 (18.1)	1964 (14.1)
40–44	5411 (17.2)	3078 (17.6)	2333 (16.8)
45–49	6222 (19.8)	3414 (19.5)	2808 (20.2)
50–54	5410 (17.2)	2899 (16.6)	2511 (18.1)
55–59	4166 (13.3)	2311 (13.2)	1855 (13.3)
60–64	2714 (8.6)	1378 (7.9)	1336 (9.6)
65–69	1430 (4.6)	756 (4.3)	674 (4.8)
70–74	555 (1.8)	297 (1.7)	258 (1.9)
75–79	243 (0.8)	134 (0.8)	109 (0.8)
80 ~	116 (0.4)	60 (0.3)	56 (0.4)
Mean age ± SD (years)	49.3 ± 10.2	48.8 ± 10.2	49.8 ± 10.1	< 0.001
Smoking status				< 0.001
Non-smoking	21,427 (68.3)	8183 (46.8)	13,244 (95.2)
Smoking	9967 (31.7)	9307(53.2)	660 (4.8)
Smoking volume (pack year)
< 10	2452 (24.6)	2187 (23.5)	265 (40.2)
10 ~ 19	2474 (24.8)	2324 (25.0)	150 (22.7)
20 ~ 29	2289 (23.0)	2147 (23.1)	142 (21.5)
30 ~	2752 (27.6)	2649 (28.5)	103 (15.6)
Passive smoking (pack year)				< 0.001
Unknown	17,439 (55.6)	6700 (38.3)	10,739 (77.2)
No	4629 (14.7)	2089 (11.9)	2540 (18.3)
Yes	9326 (29.7)	8701 (49.7)	625 (4.5)
< 20	4622 (49.6)	4227 (48.6)	395 (63.2)
20–29	2128 (22.8)	1994 (22.9)	134 (21.4)
30 ~	2576 (27.6)	2480 (28.5)	96 (15.4)
Quit smoking time (years)				< 0.001
No	28,119 (89.6)	14,395 (82.3)	13,724 (98.7)
Yes	3275 (10.4)	3095 (17.7)	180 (1.3)
≥ 15	925 (28.2)	886 (28.6)	39 (21.7)
< 15	2350 (71.8)	2209 (71.4)	141 (78.3)
Family history of lung cancer				< 0.001
Yes	5060 (16.1)	2624 (15.0)	2436 (17.5)
No	26,334 (83.9)	14,866 (85.0)	11,468 (82.5)
History of occupational exposure				< 0.001
Yes	1492 (5.0)	1213 (7.0)	297 (2.1)
No	29,902 (95.0)	16,277 (93.0)	13,625 (97.9)

Abbreviation: SD Standard deviation