Table 3.
Associations Between Cigarette Smoking and EBV Reactivation in Population-Based Individuals, Southern China, 2010–2014
| Variables | EBV Reactivation Statusa | OR (95% CI)b | P Valueb | |
|---|---|---|---|---|
| Negative | Positive | |||
| Cigarette Smoking | ||||
| Never smokerc | 719 | 176 | 1.00 (ref.) | |
| Former smoker | 86 | 28 | 1.16 (0.71–1.92) | .55 |
| Current smoker | 679 | 227 | 1.37 (1.02–1.83) | .03 |
| P trendd | 0.03 | |||
| Age at Smoking Initiation, Years | ||||
| ≥30 | 113 | 30 | 0.99 (0.62–1.60) | .98 |
| 20 to <30 | 352 | 115 | 1.31 (0.95–1.82) | .10 |
| <20 | 300 | 109 | 1.51 (1.08–2.11) | .02 |
| P trendd | 0.01 | |||
| Cigarettes Smoked Per Day | ||||
| <10 | 204 | 73 | 1.35 (0.93–1.95) | .11 |
| 10 to <20 | 213 | 74 | 1.44 (1.00–2.08) | .05 |
| 20 to <30 | 276 | 80 | 1.21 (0.85–1.72) | .298 |
| ≥30 | 72 | 27 | 1.49 (0.90–2.49) | .13 |
| P trendd | 0.16 | |||
| Duration of Smoking, Years | ||||
| <10 | 60 | 12 | 0.99 (0.50–1.94) | .97 |
| 10 to <20 | 157 | 40 | 1.22 (0.79–1.87) | .37 |
| 20 to <30 | 224 | 66 | 1.27 (0.88–1.84) | .20 |
| ≥30 | 324 | 136 | 1.52 (1.08–2.13) | .02 |
| P trendd | 0.02 | |||
| Pack-Years of Smoking | ||||
| <10 | 234 | 67 | 1.21 (0.84–1.75) | .31 |
| 10 to <20 | 164 | 49 | 1.30 (0.87–1.95) | .20 |
| 20 to <30 | 154 | 52 | 1.39 (0.93–2.08) | .11 |
| ≥30 | 213 | 86 | 1.49 (1.03–2.14) | .03 |
| P trendd | 0.03 | |||
| Type of Cigarette | ||||
| Filtered | 541 | 155 | 1.22 (0.90–1.65) | .21 |
| Unfiltered | 224 | 100 | 1.67 (1.17–2.38) | .01 |
| P trendd | 0.01 | |||
| Type of Smoking, Inhaled or Not | ||||
| Not deeply inhaled | 418 | 130 | 1.25 (0.91–1.72) | .17 |
| Deeply inhaled | 347 | 125 | 1.45 (1.05–2.00) | .02 |
| P trendd | 0.02 | |||
Abbreviations: CI, confidence interval; IgA, immunoglobulin A; EBNA1/IgA, IgA antibodies against EBV nuclear antigen 1; EBV, Epstein-Barr virus; OR, odds ratio; ref., reference; VCA/IgA, IgA antibodies against EBV capsid antigens.
Two EBV serological markers (VCA/IgA, EBNA1/IgA) were used to determine the status of EBV reactivation. An EBV score was calculated using a formula: Score = [e (−3.934 + 2.203 × VCA/IgA + 4.797 × EBNA1/IgA)]/[1 + e (−3.934 + 2.203 × VCA/IgA + 4.797 × EBNA1/IgA)]. Score < 0.65 was defined as negative, whereas Score ≥ 0.65 was defined as positive.
OR estimates and P values were calculated using logistic regression, adjusted for age (continuous variable), sex, geographic area, and educational level.
Never smokers were the reference group for all comparisons.
Linear trend tests were conducted by using the median value within each category or by treating the categorical variable as an ordinal variable.