Table 4.
Interaction Analysis of Smoking Status and Oral Epstein-Barr Virus (EBV) Levels Among Healthy Subjects in Different Geographical Areas of China
| Smoking Status |
Subjects in Northern Chinaa | Subjects in Southern Chinaa | ||||
|---|---|---|---|---|---|---|
| Low/High EBV Loads b | Adjusted OR (95%CI) c |
P | Low/High EBV Loads b | Adjusted OR (95%CI) c |
P | |
| Never | 1181/672 | 1.00 (reference) | / | 749/757 | 1.61 (1.37–1.89) | <.001 |
| Current | 711/815 | 1.61 (1.37–1.88) | <.001 | 315/721 | 3.06 (2.55–3.67) | <.001 |
| AP d | … | 0.28 (.14–.41) | … | … | ||
| SI d | … | 1.69 (1.24–2.31) | … | … | ||
aSubjects in northern China are from the north and northeast populations, where the annual incidence of nasopharyngeal carcinoma (NPC) was <1 case/100000 persons; subjects in southern China are from the 21RCCP and south populations, where the NPC incidence was >20 cases/100000 persons.
bOral 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.
cLogistic 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).
dThe attributable proportion (AP) and synergism index (SI) due to additive interaction were calculated.