Table 1.

The associations between demographic, clinical characteristics, and nasopharyngeal carcinoma in Guangdong population

Variablesa	No. of Healthy controls (%)	No. of NPC cases (%)	Adjusted OR (95%CI)b	P c
Age	46 ± 12	46 ± 11		.556
Sex
Female	491 (29.65)	254 (26.24)
Male	1165 (70.35)	714 (73.76)		.062
Education years
≤6	225 (13.63)	237 (24.56)	1.00 (reference)	/
7‐12	891 (53.97)	604 (62.59)	0.57 (0.45‐0.71)	<.001
>13	535 (32.40)	124 (12.85)	0.20 (0.14‐0.26)	<.001
P trend d				<.001
VCA‐IgA
Negative	1322 (81.00)	37 (3.85)	1.00 (reference)	/
Positive	310 (19.00)	923 (96.15)	115.08 (79.16‐167.29)	<.001
EA‐IgA
Negative	1628 (99.75)	215 (22.42)	1.00 (reference)	/
Positive	4 (0.25)	744 (77.58)	1409.70 (518.80‐3830.53)	<.001
Oral EBV load
P0‐P25	412 (24.88)	366 (37.81)	1.00 (reference)	/
P25‐P25	414 (25.00)	251 (25.93)	0.69 (0.55‐0.86)	.001
P50‐P75	414 (25.00)	218 (22.52)	0.62 (0.49‐0.79)	<.001
P75‐P100	416 (25.12)	133 (13.74)	0.33 (0.26‐0.43)	<.001
P trend d				<.001

^aFor age, mean, and standard deviation were descried among cases and controls.

^bMultivariable logistic regressions were used by adjusting age (continuous variables), sex (males and females), education years (≤6, 7‐12, >13), cigarette smoking pack‐years (non‐smoker, <20, ≥20), alcohol drinking (non‐drinker, ≤1 drink per day, >1 drink per day), consumption of preserved vegetable (less than monthly, monthly, weekly, or more), and consumption of salted‐fish (less than monthly, monthly, weekly, or more).

^cMann‐Whitney U test were used for comparison of age between 2 groups; chi‐square test was used for comparison of sex between 2 groups; multivariable logistic regressions were used for comparison of other category variables between 2 groups.

^dLinear trends tests were performed by treating ordered categorical variables as continuous variables.