Table 2. Odds ratios of OL and OSF associated with cigarette smoking and alcohol drinking, Taiwan.

	Oral leukoplakia			Oral submucous fibrosis
Factor/category	No. of cases	No. of controls	ORa (95% CI)	No. of cases	No. of controls	ORa (95% CI)
Cigarette smoking
Neverb	19	258	1.0	10	188	1.0
Ex	6	16	5.6 (1.9–16.6)	5	14	6.5 (1.9–22.3)
Current	100	226	6.1 (3.4–10.6)	79	174	7.0 (3.5–14.3)
Dose–response			2.4 (1.8–3.1)			2.5 (1.8–3.5)
Cumulative pack-years
1–10	32	84	5.3 (2.7–10.4)	36	95	5.7 (2.6–12.3)
11–20	26	66	5.4 (2.7–10.9)	20	41	8.6 (3.6–20.7)
>20	48	92	7.0 (3.7–13.2)	28	52	8.6 (3.7–20.2)
Dose–response			1.8 (1.5–2.1)			2.0 (1.5–2.5)
Alcohol drinking
Neverb	72	349	1.0	55	266	1.0
Ex	9	40	1.1 (0.5–2.4)	7	27	1.4 (0.6–3.4)
Current	44	111	1.8 (1.1–2.8)	32	83	1.8 (1.1–3.1)
Dose–response			1.3 (1.1–1.7)			1.4 (1.0–1.8)
Drinking frequency
Monthly	9	40	1.1 (0.5–2.4)	7	27	1.4 (0.6–3.4)
Weekly	24	60	1.9 (1.1–3.3)	17	42	1.9 (1.0–3.7)
Daily	20	51	1.7 (0.9–3.0)	15	41	1.7 (0.9–3.5)
Dose–response			1.2 (1.0–1.5)			1.2 (1.0–1.5)

^aOdds ratios were adjusted for education and occupation.

^bNever smokers and never drinkers were reference categories, respectively.