Comparison 6. Subgroup by duration of contact.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Cessation at longest follow‐up	53	25375	Risk Ratio (M‐H, Fixed, 95% CI)	2.29 [2.13, 2.46]
1.1 No personal contact scheduled	1	1023	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.69, 1.58]
1.2 Up to 30 minutes	5	1719	Risk Ratio (M‐H, Fixed, 95% CI)	1.70 [1.24, 2.33]
1.3 31‐90 minutes	17	8718	Risk Ratio (M‐H, Fixed, 95% CI)	1.96 [1.74, 2.21]
1.4 91‐300 minutes	22	5758	Risk Ratio (M‐H, Fixed, 95% CI)	1.84 [1.60, 2.11]
1.5 Over 300 minutes	7	2270	Risk Ratio (M‐H, Fixed, 95% CI)	1.70 [1.34, 2.16]
1.6 Lung Health Study (over 300 mins)	1	5887	Risk Ratio (M‐H, Fixed, 95% CI)	3.88 [3.35, 4.50]