Table 1.

Smoking characteristics associated with rapid progression to tobacco dependence among recently initiated cigarette smokers

	Non-dependent		Tobacco dependent
	n	%a	n	%a (95% CI)	Unadjusted odds ratio	Adjustedb odds ratio
Months since onset
0–11 months	479	91.4	47	8.6 (6.1–12.2)	1.0	1.0
12–24 months	1045	84.4	163	15.6 (13.0–18.7)	2.0 (1.3, 3.0)	1.8 (1.1, 3.0)
Ever smoke daily
No	1290	93.8	75	6.2 (4.8–8.1)	1.0	1.0
Yes	227	58.9	134	41.1 (34.5–48.0)	10.5 (7.2, 15.3)	11.4 (7.5, 17.5)
Missing	7	91.1	1	8.8 (1.1–45.4)
Number of days smoked in life
1–2 days	904	97.1	25	2.9 (1.8–4.8)	1.0	1.0
3–11 days	293	87.3	43	12.7 (9.0–7.6)	4.8 (2.6, 9.1)	4.5 (2.3, 8.6)
12–100 days	158	67.7	67	32.3 (25.3–40.1)	15.8 (8.7, 28.9)	13.2 (7.1, 24.5)
⩾101 days	142	59.9	73	40.0 (32.9–47.6)	22.1 (11.8, 41.5)	26.9 (14.7, 49.2)
Missing	27	96.4	2	3.6 (0.7–16.7)
Number of days used in past 30 days
0 days	847	96.4	29	3.6 (2.4–5.4)	1.0	1.0
1–2 days	250	90.6	25	9.4 (5.5–5.7)	2.8 (1.3, 5.9)	2.3 (1.0, 5.3)
3–7 days	88	71.2	37	28.8 (18.9–41.4)	10.9 (5.5, 21.6)	10.2 (4.9, 21.4)
8–14 days	38	57.9	18	42.1 (29.2–56.1)	19.6 (9.1, 42.0)	16.2 (6.7, 39.1)
22–31 days	91	52.3	64	47.7 (38.5–57.1)	24.6 (14.1, 42.9)	23.6 (13.5, 41.2)
Not applicable	210	82.8	62	17.2 (12.5–23.2)
Time until first smoke upon waking (past 30 days)
⩾1 hours	347	76.6	102	23.4 (19.0–28.4)	1.0	1.0
31–60 minutes	18	35.1	24	64.9 (45.8–80.2)	6.0 (2.7, 13.7)	6.5 (2.8, 15.0)
6–30 minutes	30	49.2	19	50.8 (35.1–66.3)	3.4 (1.6, 7.3)	3.0 (1.2, 7.6)
≤5 minutes	39	65.1	14	34.9 (19.0–54.9)	1.8 (0.7, 4.3)	1.8 (0.7, 5.0)
Not applicable	1090	95.1	51	4.9 (3.5–6.7)

^aNote. Weighted prevalence.

^bModels included covariates for demographic characteristics (age, gender, ethnicity), past year marijuana use and alcohol dependence.