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Table 3 The association between cigarette smoking and nasopharyngeal EBV DNA positivity, serum VCA/IgA antibody status

From: Lack of association between cigarette smoking and Epstein Barr virus reactivation in the nasopharynx in people with elevated EBV IgA antibody titres

Variable Nasopharyngeal EBV DNA VCA/IgA titer
Negative Positive ORa (95% CI) ORb (95% CI) Negative or 1:5 ≥ 1:10 ORa (95% CI) ORc (95% CI)
Smoking status
 Never smokerd 6 31 1.00 (reference) 1.00 (reference) 11 26 1.00 (reference) 1.00 (reference)
 Former smoker 4 36 1.28 (0.49–3.32) 1.34 (0.51–3.54) 12 28 0.96 (0.45–2.06) 0.72 (0.32–1.58)
 Current smoker 31 205 1.74 (0.45–6.74) 1.73 (0.43–6.69) 72 164 0.99 (0.37–2.62) 0.76 (0.27–2.09)
Age at smoking initiation (years)
 < 20 20 107 1.04 (0.38–2.80) 1.06 (0.38–2.95) 41 86 0.89 (0.40–1.97) 0.64 (0.28–1.49)
 ≥20 15 134 1.73 (0.62–4.82) 1.79 (0.63–5.07) 43 106 1.04 (0.47–2.30) 0.79 (0.35–1.81)
Smoking intensity (cigarettes/day)
 ≤10 6 45 1.60 (0.46–5.58) 1.75 (0.50–6.21) 20 31 0.61 (0.24–1.56) 0.54 (0.21–1.39)
 11–30 27 167 1.19 (0.44–3.21) 1.20 (0.44–3.24) 51 143 1.01 (0.45–2.25) 0.92 (0.41–2.08)
 > 30 2 29 2.91(0.53–15.80) 3.08 (0.56–16.85) 13 18 0.51 (0.18–1.43) 0.45 (0.16–1.29)
Smoking duration (years)
 ≤15 3 21 1.36 (0.31–6.03) 2.12(0.42–10.80) 9 15 0.71 (0.24–2.09) 0.80 (0.24–2.68)
 16–30 17 106 1.21 (0.44–3.32) 1.37 (0.49–3.84) 42 81 0.82 (0.37–1.81) 0.71 (0.31–1.64)
 > 30 15 114 1.47 (0.53–4.11) 1.20 (0.36–3.93) 33 96 1.23 (0.55–2.76) 0.71 (0.28–1.79)
Type of cigarettes smoked
 filtered cigarettes 21 153 1.41 (0.53–3.78) 1.55 (0.57–4.23) 48 126 1.11 (0.51–2.42) 2.32 (0.94–5.75)
 non-filtered cigarettes 3 31 2.00 (0.46–8.72) 1.52 (0.33–7.05) 9 25 1.18 (0.42–3.32) 2.30 (0.88–4.39)
 both type 11 57 1.00 (0.38–2.97) 0.97 (0.31–3.01) 27 41 0.64 (0.27–1.51) 1.90 (0.72–4.81)
Cumulative smoking (pack-years)
 < 20 13 82 1.22 (0.43–3.50) 1.03 (0.30–2.58) 35 60 0.73 (0.32–1.65) 0.64 (0.27–1.50)
 20–39 15 121 1.56 (0.56–4.35) 1.44 (0.49–4.27) 35 101 1.22 (0.55–2.73) 0.83 (0.36–1.95)
 ≥40 7 38 1.05 (0.32–3.45) 1.59 (0.59–4.29) 14 31 0.94 (0.36–2.41) 0.68 (0.25–1.86)
  1. aThe OR without adjustment; b OR adjusted for residential area, age, education level, VCA/IgA antibody titers; c OR adjusted for residential area, age, education level, nasopharyngeal EBV DNA load; d Never smokers were the reference group for all comparisons. Abbreviation: EBV, Epstein-Barr virus; VCA/IgA, IgA antibodies against viral capsid antigen; CI, confidence interval
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