Table 3.
Dose-Response Between Cigarette Smoking and Oral Epstein-Barr Virus (EBV) Levels Among Healthy Subjects in China
| Variable | Current Smoker | Former Smoker | ||||
|---|---|---|---|---|---|---|
| Low/High EBV Loadsa | Adjusted OR (95% CI)b | P | Low/High EBV Loadsa | Adjusted OR (95% CI)b | P | |
| Age at smoking initiation, y | ||||||
| Never | 1930/1429 | 1.00 (reference) | 1930/1429 | 1.00 (reference) | ||
| ≥20 | 548/847 | 1.71 (1.48–1.98) | <.001 | 168/165 | 1.02 (.80–1.31) | .834 |
| <20 | 472/682 | 1.68 (1.43–1.97) | <.001 | 145/140 | 1.04 (.80–1.34) | .763 |
| P trend c | <.001 | .736 | ||||
| Daily smoking amount, packs | ||||||
| Never | 1930/1429 | 1.00 (reference) | 1930/1429 | 1.00 (reference) | ||
| <1 | 447/573 | 1.46 (1.25–1.72) | <.001 | 141/109 | 0.84 (.64–1.10) | .203 |
| ≥1 | 569/957 | 1.91 (1.64–2.21) | <.001 | 137/169 | 1.28 (1.00–1.65) | .054 |
| P trend c | <.001 | .169 | ||||
| Smoking duration, y | ||||||
| Never | 1930/1429 | 1.00 (reference) | 1930/1429 | 1.00 (reference) | ||
| ≤25 | 532/682 | 1.61 (1.37–1.88) | <.001 | 174/171 | 1.10 (.87–1.40) | .414 |
| >25 | 486/851 | 1.80 (1.54–2.11) | <.001 | 105/108 | 0.98 (.73–1.32) | .886 |
| P trend c | <.001 | .811 | ||||
| Cumulative amount smoked, pack-years | ||||||
| Never | 1930/1429 | 1.00 (reference) | 1930/1429 | 1.00 (reference) | ||
| <20 | 538/685 | 1.53 (1.32–1.79) | <.001 | 166/153 | 1.02 (.80–1.30) | .888 |
| ≥20 | 479/845 | 1.89 (1.62–2.21) | <.001 | 112/125 | 1.11 (.84–1.48) | .455 |
| P trend c | <.001 | .486 | ||||
| Smoking type, inhaled or not inhaled | ||||||
| Never | 1930/1429 | 1.00 (reference) | 1930/1429 | 1.00 (reference) | ||
| Did not inhale | 405/533 | 1.49 (1.26–1.75) | <.001 | 136/110 | 0.89 (.67–1.17) | .397 |
| Inhaled | 597/973 | 1.85 (1.60–2.14) | <.001 | 167/179 | 1.11 (.88–1.42) | .378 |
| P trend c | <.001 | 0.554 | .554 | |||
aOral EBV levels were divided into low and high levels according to the median number of EBV copies in saliva or mouthwash, per milliliter. For mouthwash EBV loads in the 21RCCP population, a low EBV level refers to <104.55 copies/mL of mouthwash and a high EBV level refers to ≥104.55 copies/mL of mouthwash; for salivary EBV loads in the south, north, and northeast populations, a low EBV level refers to <104.47 copies/mL of saliva, and a high EBV level refers to ≥104.47 copies/mL of saliva.
bLogistic regression analyses were used to assess odds ratios (ORs) and 95% confidence intervals (CIs) by adjusting for age (continuous variable), sex (male or female), education level (high school and less or university and greater), and alcohol consumption (nondrinker, ≤1 drink/day, or >1 drink/day).
cLinear trends tests were performed by treating ordered categorical variables as continuous variables.