Brain tumours and cigarette smoking: analysis of the INTERPHONE Canada case–control study

Table 5 Odds ratios between ever versus never regular smoking for glioma by education level

Sex/education stratum	Glioma
	Ca/Co	OR (95% CI)
*Males and females combined*
Ever regular smoking-education interaction p = 0.010
Ever versus never regular smoking, lower education	64/186	1.33 (0.62-2.85)
Ever versus never regular smoking, higher education	102/462	0.48 (0.25-0.91)
*Males only*
Ever regular smoking-education interaction p = 0.032
Ever versus never regular smoking, lower education	39/87	2.79 (1.08-7.18)
Ever versus never regular smoking, higher education	66/230	0.85 (0.49-1.48)
*Females only*
Ever regular smoking-education interaction p = 0.066
Ever versus never regular smoking, lower education	25/99	1.31 (0.53-3.22)
Ever versus never regular smoking, higher education	36/232	0.42 (0.19-0.95)

Models were of ever regular smoking as a binary variable, with the addition of an interaction term of ever regular smoking and education level. The reference groups in all comparisons are never regular smokers in the appropriate sex and education stratum. Analyses were adjusted for age (decades); sex (in the analysis of males and females combined); and region (Montreal, Ottawa, Vancouver). Covariates were removed from the model if they were non-significant and did not change any of the smoking ORs by more than 10%.

ISSN: 1476-069X