Comparison 1. Effect of increasing behavioural support. Abstinence at longest follow‐up.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Subgroups by type of pharmacotherapy	65	23331	Risk Ratio (M‐H, Random, 95% CI)	1.15 [1.08, 1.22]
1.1 NRT	49	16541	Risk Ratio (M‐H, Random, 95% CI)	1.12 [1.04, 1.21]
1.2 Bupropion	5	2298	Risk Ratio (M‐H, Random, 95% CI)	1.27 [1.10, 1.46]
1.3 Nortriptyline	2	172	Risk Ratio (M‐H, Random, 95% CI)	0.98 [0.60, 1.63]
1.4 Varenicline	2	1111	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.87, 1.27]
1.5 NRT & bupropion	3	719	Risk Ratio (M‐H, Random, 95% CI)	1.24 [1.00, 1.54]
1.6 Choice of pharmacotherapy	5	2490	Risk Ratio (M‐H, Random, 95% CI)	1.30 [1.00, 1.68]
2 Subgroups by contrast in number of contacts between intervention & control	63	21997	Risk Ratio (M‐H, Random, 95% CI)	1.15 [1.08, 1.22]
2.1 4 to 8 or > 8 contacts versus no contact	8	4018	Risk Ratio (M‐H, Random, 95% CI)	1.20 [1.02, 1.43]
2.2 More than 8 contacts versus 1 to 3 contacts	4	1063	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.70, 1.57]
2.3 4 to 8 contacts versus 1 to 3 contacts	18	9579	Risk Ratio (M‐H, Random, 95% CI)	1.10 [1.01, 1.19]
2.4 More than 8 contacts versus 4 to 8 contacts	12	1737	Risk Ratio (M‐H, Random, 95% CI)	1.15 [0.98, 1.33]
2.5 Intervention & control in same contact category	21	5600	Risk Ratio (M‐H, Random, 95% CI)	1.32 [1.16, 1.50]
3 Subgroups by duration of contact in control condition (not prespecified)	62	21695	Risk Ratio (M‐H, Random, 95% CI)	1.15 [1.08, 1.22]
3.1 No contact for control	8	4018	Risk Ratio (M‐H, Random, 95% CI)	1.20 [1.02, 1.43]
3.2 'Brief intervention' for control	22	10565	Risk Ratio (M‐H, Random, 95% CI)	1.09 [0.99, 1.21]
3.3 'Dose response', over 30 minutes contact for control	32	7112	Risk Ratio (M‐H, Random, 95% CI)	1.19 [1.08, 1.32]
4 Subgroup by modality of intervention contact (not prespecified)	65	23331	Risk Ratio (M‐H, Random, 95% CI)	1.15 [1.08, 1.22]
4.1 Intervention delivered by telephone	8	6670	Risk Ratio (M‐H, Random, 95% CI)	1.25 [1.15, 1.37]
4.2 Intervention included face‐to‐face contact	57	16661	Risk Ratio (M‐H, Random, 95% CI)	1.11 [1.03, 1.19]