Individual and joint effects of smoking and drinking on oral and oropharyngeal cancer adjusted for gender, age, schooling level.

Model-1 did not account for the smoking-drinking interaction, smoking and drinking were therefore treated only as confounders. Model-2 accounted for the smoking-drinking interaction. aModel-1: Pseudo-R2 = 0.118; −2log likelihood = 3346.826. Model-2: Pseudo-R2 = 0.134; −2log likelihood = 3285.967. Difference in goodness of fit between Model-1 and Model-2: likelihood ratio test χ2 = 60.859, p<0.001. bModel-1: Pseudo-R2 = 0.175; −2log likelihood = 3130.079. Model-2: Pseudo-R2 = 0.186; −2log likelihood = 3088.889. Difference in goodness of fit between Model-1 and Model-2: likelihood ratio test χ2 = 41.190, p<0.001.