Comparison 4. Subgroup by treatment provider.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Cessation at longest follow‐up	53		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
1.1 Usual care provider	9	5112	Risk Ratio (M‐H, Fixed, 95% CI)	2.03 [1.70, 2.43]
1.2 Specialist cessation provider	39	12252	Risk Ratio (M‐H, Fixed, 95% CI)	1.81 [1.64, 1.99]
1.3 Peer supporter	2	799	Risk Ratio (M‐H, Fixed, 95% CI)	1.75 [1.19, 2.58]
1.4 Lay health adviser	1	302	Risk Ratio (M‐H, Fixed, 95% CI)	28.46 [1.71, 474.46]
1.5 Mail contact only	1	1023	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.69, 1.58]
1.6 Lung Health Study (specialist)	1	5887	Risk Ratio (M‐H, Fixed, 95% CI)	3.88 [3.35, 4.50]