Comparison 1. Adjunctive counseling (patient‐level).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Long‐term abstinence (subgrouped by single vs. multicomponent intervention type)	22	18150	Risk Ratio (M‐H, Random, 95% CI)	1.31 [1.10, 1.55]
1.1.1 Adjunctive counseling + standard care vs standard care	17	12852	Risk Ratio (M‐H, Random, 95% CI)	1.43 [1.15, 1.78]
1.1.2 Adjunctive counseling + multicomponent int vs multicomponent int	5	5298	Risk Ratio (M‐H, Random, 95% CI)	1.04 [0.87, 1.23]
1.2 Long‐term abstinence (subgrouped by provider)	22	18150	Risk Ratio (M‐H, Random, 95% CI)	1.31 [1.10, 1.55]
1.2.1 Nurses	11	3214	Risk Ratio (M‐H, Random, 95% CI)	1.20 [0.97, 1.50]
1.2.2 Psychologists & counselors	12	14835	Risk Ratio (M‐H, Random, 95% CI)	1.31 [1.03, 1.66]
1.2.3 Pharmacists	1	101	Risk Ratio (M‐H, Random, 95% CI)	2.38 [0.99, 5.70]
1.3 Long‐term abstinence (subgrouped by mode)	22	18150	Risk Ratio (M‐H, Random, 95% CI)	1.31 [1.10, 1.55]
1.3.1 Face to face	14	11753	Risk Ratio (M‐H, Random, 95% CI)	1.31 [1.06, 1.61]
1.3.2 Telephone	10	6397	Risk Ratio (M‐H, Random, 95% CI)	1.31 [0.98, 1.75]
1.4 Long‐term abstinence (subgrouped by intensity)	22	18150	Risk Ratio (M‐H, Random, 95% CI)	1.31 [1.10, 1.55]
1.4.1 Brief/minimal	6	2533	Risk Ratio (M‐H, Random, 95% CI)	1.42 [1.07, 1.88]
1.4.2 More substantial	18	15617	Risk Ratio (M‐H, Random, 95% CI)	1.28 [1.04, 1.57]
1.5 Advise rates	2	724	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.93, 1.26]
1.5.1 Adjunctive counseling + standard care vs standard care	1	190	Risk Ratio (M‐H, Random, 95% CI)	1.20 [0.94, 1.54]
1.5.2 Adjunctive counseling + multicomponent int vs multicomponent int	1	534	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.87, 1.19]
1.6 Assistance rates	5		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.6.1 Medication	3	1094	Risk Ratio (M‐H, Random, 95% CI)	1.61 [1.20, 2.15]
1.6.2 Counseling	3	1460	Risk Ratio (M‐H, Random, 95% CI)	1.64 [0.94, 2.88]
1.6.3 Quit date set	1	190	Risk Ratio (M‐H, Random, 95% CI)	1.42 [0.58, 3.44]
1.6.4 Self‐help materials	1	190	Risk Ratio (M‐H, Random, 95% CI)	1.00 [0.70, 1.42]
1.7 Arrange follow‐up support rates	3		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.7.1 Adjunctive counseling + standard care vs standard care	3	1718	Risk Ratio (M‐H, Random, 95% CI)	4.65 [1.67, 12.90]
1.8 Quit attempts	3		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.8.1 Adjunctive counseling + standard care vs standard care	3	1764	Risk Ratio (M‐H, Random, 95% CI)	1.23 [1.02, 1.49]