Table 4.

Relative odds of remaining abstinent for 28 days or longer among those making quit attempts (of known duration), by country and type of support received (Waves 1–4)

Country	Adjusted odds ratio (95% CI)
The United Kingdom	Referent
Australia	0.59 (0.49–0.71)
Canada	0.72 (0.61–0.87)
The United States	0.51 (0.42–0.62)
By use of support (mutually exclusive categories vs. no support)
Smoking cessation clinic or helpline	1.38 (1.09–1.75)
The United Kingdom	1.92 (1.20–3.06)
Australia	0.56 (0.30–1.02)
Canada	2.00 (1.30–3.09)
The United States	1.25 (0.75–2.08)
Pharmacotherapy	1.61 (1.43–1.83)
The United Kingdom	1.50 (1.18–1.90)
Australia	1.45 (1.15–1.83)
Canada	2.03 (1.62–2.54)
The United States	1.29 (0.96–1.74)
Help from a doctor or other health professional	1.42 (1.09–1.84)
The United Kingdom	0.72 (0.43–1.19)
Australia	2.45 (1.48–4.06)
Canada	1.92 (1.12–3.29)
The United States	1.21 (0.70–2.10)
Both pharmacotherapy and help from a clinic, helpline, doctor, or other health professional	2.04 (1.70–2.46)
The United Kingdom	2.13 (1.58–2.87)
Australia	1.96 (1.32–2.90)
Canada	2.13 (1.48–3.08)
The United States	1.14 (0.71–1.85)