Table 4.
The associations between potential risk factors and oral Epstein‐Barr virus load levels among NPC cases and healthy controls
| Variables | NPC cases | Healthy controls | ||||||
|---|---|---|---|---|---|---|---|---|
| EBV loads (copies/mL)a | Adjusted OR (95% CI)b | P | EBV loads (copies/mL)a | Adjusted OR (95% CI)b | P | |||
| <33 978 , N(%) | ≥33 978, N(%) | <33 987, N(%) | ≥33 987, N(%) | |||||
| Age | ||||||||
| <40 | 182 (29.50) | 83 (23.65) | 1.00 (reference) | / | 288 (34.78) | 223 (26.93) | 1.00 (reference) | / |
| 40‐49 | 206 (33.39) | 112 (31.91) | 1.36 (0.94‐1.96) | .101 | 271 (32.73) | 229 (27.66) | 1.06 (0.82‐1.38) | .647 |
| 50‐59 | 164 (26.58) | 105 (29.91) | 1.73 (1.18‐2.55) | .005 | 173 (20.89) | 247 (29.83) | 1.75 (1.32‐2.34) | <.001 |
| ≥60 | 65 (10.53) | 51 (14.53) | 2.18 (1.34‐3.56) | .002 | 96 (11.59) | 129 (15.58) | 1.65 (1.17‐2.34) | .005 |
| P trend c | <.001 | <.001 | ||||||
| Sex | ||||||||
| Female | 172 (27.88) | 82 (23.36) | 1.00 (reference) | / | 308 (37.20) | 183 (22.10) | 1.00 (reference) | / |
| Male | 445 (72.12) | 269 (76.64) | 1.34 (0.90‐2.00) | .155 | 520 (62.80) | 645 (77.90) | 1.65 (1.25‐2.18) | <.001 |
| Education years | ||||||||
| ≤6 | 166 (26.99) | 71 (20.29) | 1.00 (reference) | / | 118 (14.29) | 107 (12.97) | 1.00 (reference) | / |
| 7‐12 | 374 (60.81) | 230 (65.71) | 1.55 (1.09‐2.21) | .015 | 444 (53.75) | 447 (54.18) | 1.29 (0.94‐1.78) | .111 |
| >13 | 75 (12.20) | 49 (14.00) | 1.65 (1.00‐2.72) | .049 | 264 (31.96) | 271 (32.85) | 1.59 (1.11‐2.26) | .011 |
| P trend c | .027 | .010 | ||||||
| VCA‐IgA | ||||||||
| ≤1:40 | 64 (10.37) | 73 (20.80) | 1.00 (reference) | / | 822 (99.28) | 821 (99.15) | 1.00 (reference) | / |
| 1:40‐1:160 | 199 (32.25) | 120 (34.19) | 0.51 (0.34‐0.78) | .002 | 5 (0.60) | 5 (0.60) | 0.95 (0.26‐3.51) | .934 |
| 1:160‐1:640 | 288 (46.68) | 134 (38.18) | 0.38 (0.25‐0.57) | <.001 | 1 (0.12) | 2 (0.24) | 1.47 (0.13‐17.09) | .759 |
| >1:640 | 66 (10.70) | 24 (6.84) | 0.28 (0.15‐0.51) | <.001 | 0 (0.00) | 0 (0.00) | .862 | |
| P trend c | <.001 | |||||||
| EA‐IgA | ||||||||
| ≤1:10 | 224 (36.30) | 166 (47.29) | 1.00 (reference) | / | 828 (100.00) | 828 (100.00) | 1.00 (reference) | / |
| 1:10‐1:40 | 218 (35.33) | 114 (32.48) | 0.63 (0.46‐0.87) | .005 | 0 (0.00) | 0 (0.00) | / | / |
| 1:80‐1:160 | 149 (24.15) | 68 (19.37) | 0.52 (0.36‐0.75) | <.001 | 0 (0.00) | 0 (0.00) | / | / |
| >1:160 | 26 (4.21) | 3 (0.85) | 0.14 (0.04‐0.49) | .002 | 0 (0.00) | 0 (0.00) | / | / |
| P trend c | <.001 | / | ||||||
| Overall stage | ||||||||
| I | 19 (3.34) | 12 (3.55) | 1.00 (reference) | / | ||||
| II | 93 (16.34) | 56 (16.57) | 1.10 (0.48‐2.49) | .824 | ||||
| III | 304 (53.43) | 168 (49.70) | 0.98 (0.46‐2.13) | .968 | ||||
| IV | 153 (26.89) | 102 (30.18) | 1.11 (0.50‐2.46) | .800 | ||||
| P trend c | .840 | |||||||
| T stage | ||||||||
| T1 | 39 (6.63) | 15 (4.36) | 1.00 (reference) | / | ||||
| T2 | 163 (27.72) | 77 (22.38) | 1.30 (0.66‐2.53) | .446 | ||||
| T3 | 276 (46.94) | 158 (45.93) | 1.58 (0.83‐3.00) | .165 | ||||
| T4 | 110 (18.71) | 94 (27.33) | 2.32 (1.17‐4.57) | .015 | ||||
| P trend c | .002 | |||||||
| N stage | ||||||||
| N0 | 118 (20.03) | 108 (31.40) | 1.00 (reference) | / | ||||
| N1 | 224 (38.03) | 146 (42.44) | 0.74 (0.52‐1.04) | .085 | ||||
| N2 | 192 (32.60) | 73 (21.22) | 0.40 (0.27‐0.59) | <.001 | ||||
| N3 | 55 (9.34) | 17 (4.94) | 0.32 (0.17‐0.60) | <.001 | ||||
| P trend c | <.001 | |||||||
| M | ||||||||
| M0 | 575 (97.79) | 333 (97.65) | 1.00 (reference) | / | ||||
| M1 | 13 (2.21) | 8 (2.35) | 0.80 (0.29‐2.16) | .653 | ||||
Oral EBV loads were assigned into 2 groups based on the median of that in healthy controls (33 978 copies/mL).
Multivariable logistic regressions were used by adjusting age (continuous variables), sex (males and females), education years (≤6, 7‐12, >13), cigarette smoking pack‐years (nonsmoker, <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).
Linear trends tests were performed by treating ordered categorical variables as continuous variables.