Effect of dietary vitamin C on gastric cancer risk in the Korean population

Table 1 General characteristics of the study subjects

	Total (n = 1245)			Men (n = 810)			Women (n= 435)
	Case(n = 415)	Control(n = 830)	P value1	Case(n = 270)	Control(n = 540)	P value	Case(n = 145)	Control(n = 290)	P value
Age (yr), mean ± SD	53.8 ± 9.3	53.7 ± 9.0	0.892	54.9 ± 8.7	54.8 ± 8.4	0.905	51.7 ± 10.0	51.6 ± 9.8	0.942
Body mass index (kg/m2)
< 23	159 (38.3)	314 (37.8)	0.975	91 (33.7)	161 (29.8)	0.509	68 (46.9)	153 (52.8)	0.533
23-25	122 (29.4)	249 (30.0)		78 (28.9)	170 (31.5)		44 (30.3)	79 (27.2)
≥ 25	133 (32.1)	266 (32.1)		101 (37.4)	209 (38.7)		32 (22.1)	57 (19.7)
First-degree family history of gastric cancer
No	332 (80.0)	725 (87.4)	0.001	209 (77.4)	464 (85.9)	0.002	123 (84.8)	261 (90.0)	0.114
Yes	82 (19.8)	103 (12.4)		60 (22.2)	74 (13.7)		22 (15.2)	29 (10.0)
Marital status
Married	361 (87.0)	716 (86.3)	0.611	243 (90.0)	478 (88.5)	0.475	118 (81.4)	238 (82.1)	0.975
Other	52 (12.5)	113 (13.6)		26 (9.6)	61 (11.3)		26 (17.9)	52 (17.9)
Education level
Less than middle school	142 (34.2)	119 (14.3)	< 0.001	91 (33.7)	71 (13.2)	< 0.001	51 (35.2)	48 (16.6)	< 0.001
High school	174 (41.9)	253 (30.5)		112 (41.5)	140 (25.9)		62 (42.8)	113 (39.0)
College or higher	97 (23.4)	426 (51.3)		66 (24.4)	301 (55.7)		31 (21.4)	125 (43.1)
Job
Managers and professionals	70 (16.9)	156 (18.8)	0.001	59 (21.9)	117 (21.7)	0.010	11 (7.6)	39 (13.5)	0.002
Clerical, sales and service workers	122 (29.4)	266 (32.1)		81 (30.0)	203 (37.6)		41 (28.3)	63 (21.7)
Production workers, and laborers	104 (25.1)	128 (15.4)		83 (30.7)	111 (20.6)		21 (14.5)	17 (5.9)
Not in the labor force	117 (28.2)	277 (33.4)		46 (17.0)	106 (19.6)		71 (49.0)	171 (59.0)
Monthly household income2
< 200	133 (32.1)	149 (18.0)	< 0.001	85 (31.5)	85 (15.7)	< 0.001	48 (33.1)	64 (22.1)	0.016
200-400	148 (35.7)	341 (41.1)		106 (39.3)	232 (43.0)		42 (29.0)	109 (37.6)
≥ 400	96 (23.1)	273 (32.9)		55 (20.4)	168 (31.1)		41 (28.3)	105 (36.2)
Alcohol consumption
Non-drinker	119 (28.7)	236 (28.4)	0.243	44 (16.3)	89 (16.5)	0.282	75 (51.7)	147 (50.7)	0.819
Ex-drinker	41 (9.9)	60 (7.2)		33 (12.2)	47 (8.7)		8 (5.5)	13 (4.5)
Current drinker	254 (61.2)	534 (64.3)		193 (71.5)	404 (74.8)		61 (42.1)	130 (44.8)
Smoking status
Non-smoker	167 (40.2)	384 (46.3)	< 0.001	39 (14.4)	106 (19.6)	< 0.001	128 (88.3)	278 (95.9)	0.021
Ex-smoker	119 (28.7)	284 (34.2)		110 (40.7)	277 (51.3)		9 (6.2)	7 (2.4)
Current-smoker	128 (30.8)	162 (19.5)		121 (44.8)	157 (29.1)		7 (4.8)	5 (1.7)
Regular exercise
No	268 (64.6)	361 (43.5)	< 0.001	161 (59.6)	234 (43.3)	< 0.001	107 (73.8)	127 (43.8)	< 0.001
Yes	147 (35.4)	466 (56.1)		109 (40.4)	303 (56.1)		38 (26.2)	163 (56.2)
H. pylori infection
Negative	33 (8.0)	320 (38.6)	< 0.001	18 (6.7)	187 (34.6)	< 0.001	15 (10.3)	133 (45.9)	< 0.001
Positive	382 (92.1)	486 (58.6)		252 (93.3)	333 (61.7)		130 (89.7)	153 (52.8)

¹P values were calculated using the t test (for continuous variables) or χ² test (for categorical variables);

²Unit is 10000 won in Korean currency. Values are expressed as the mean ± SD (range) or n (%).