Outcome	Control group	Intervention group	Odds ratio (95% CI)
Participants	242	274
Quit smoking at least 24 hours before surgery*	25 (10%)	58 (21%)	2.05 (1.32–3.17)
Verified by carbon monoxide testing	22 (9%)	49 (18%)	1.97 (1.22–3.15)
Quit smoking at least four weeks before surgery*	10 (4%)	25 (9%)	2.21 (1.08–4.50)
Attempted to quit during wait for surgery †	53 (22%)	94 (34%)	1.56 (1.17–2.09)
Used medications for quitting	29 (12%)	95 (35%)	2.89 (1.98–4.22)

^*Includes twelve people (control, three; intervention, nine) for whom carbon monoxide testing could not be undertaken.

^† Attempts sustained for more than 24 hours.