Comparison 1. Group‐format behavioural programmes vs other format.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Smoking cessation. Group programme vs self‐help programme	13	4395	Risk Ratio (M‐H, Fixed, 95% CI)	1.88 [1.52, 2.33]
1.1 Group vs self‐help (same programme content)	8	2411	Risk Ratio (M‐H, Fixed, 95% CI)	2.37 [1.76, 3.20]
1.2 Group vs self‐help (different programmes)	5	1984	Risk Ratio (M‐H, Fixed, 95% CI)	1.42 [1.04, 1.94]
2 Smoking cessation. Group programme vs brief support	16	7601	Risk Ratio (M‐H, Fixed, 95% CI)	1.25 [1.07, 1.46]
2.1 Physician, nurse, or pharmacist advice	14	7286	Risk Ratio (M‐H, Fixed, 95% CI)	1.22 [1.03, 1.43]
2.2 Health Education	2	315	Risk Ratio (M‐H, Fixed, 95% CI)	1.81 [0.94, 3.46]
3 Smoking cessation. Group plus pharmacotherapy vs pharmacotherapy alone	5	1523	Risk Ratio (M‐H, Fixed, 95% CI)	1.11 [0.93, 1.33]
4 Smoking cessation. Group programme vs individual therapy	6	980	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.76, 1.28]
4.1 Group vs individual (similar intensity & content)	4	539	Risk Ratio (M‐H, Fixed, 95% CI)	1.11 [0.68, 1.81]
4.2 Group vs individual (different intensity/content)	2	441	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.69, 1.28]
5 Smoking cessation. Group vs 'no intervention' controls	9	1098	Risk Ratio (M‐H, Fixed, 95% CI)	2.60 [1.80, 3.76]