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

Table 2 Relationship between smoking and nasopharyngeal EBV load, EBV VCA/IgA antibody

Smoking characteristics	No.	EBV DNA copies, log₁₀ (Mean ± SD)	P value^a	VCA/IgA titer, log₁₀ (Mean ± SD)	P value^a
Smoking status
Never smoker	37	2.87 ± 1.60	0.384	1.05 ± 0.21	0.228
Former smoker	40	3.36 ± 1.55		1.00 ± 0.21
Current smoker	236	3.19 ± 1.58		1.07 ± 0.23
P _trend			0.251		0.551
Age at smoking initiation (years)
< 20	127	3.05 ± 1.68	0.123	1.07 ± 0.22	0.924
20–29	123	3.29 ± 1.53		1.06 ± 0.24
≥30	26	3.71 ± 1.10		1.04 ± 0.24
P _trend			0.025		0.911
Smoking intensity (cigarettes/day)
≤10	51	3.27 ± 1.47	0.604	1.06 ± 0.23	0.282
11–30	159	3.19 ± 1.62		1.07 ± 0.23
> 30	31	3.33 ± 1.49		1.00 ± 0.20
P _trend			0.273		0.327
Smoking duration (years)
≤15	24	3.23 ± 1.54	0.551	0.99 ± 0.24	0.350
16–30	123	3.14 ± 1.59		1.06 ± 0.22
> 30	129	3.29 ± 1.58		1.08 ± 0.23
P _trend			0.224		0.240
Type of cigarettes smoked
Filtered cigarettes	174	3.23 ± 1.56	0.635	1.07 ± 0.23	0.895
Non-filtered cigarettes	34	3.26 ± 1.35		1.08 ± 0.24
Both type	68	3.15 ± 1.72		1.05 ± 0.22
P _trend			0.392		0.926
Cumulative smoking (pack-years^b)
< 20	95	3.16 ± 1.53	0.202	1.03 ± 0.23	0.252
20–39	136	3.37 ± 1.59		1.09 ± 0.24
≥40	45	2.91 ± 1.58		1.04 ± 0.19
P _trend			0.768		0.846

^aComparisons were performed using one-way ANOVA; ^b pack-years = (number of cigarettes smoked per day/20) × number of years smoked. Abbreviation: EBV, Epstein-Barr virus; VCA/IgA, IgA antibodies against viral capsid antigen; SD, standard deviation

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