It is very uncertain whether more changes smoking abstinence compared with less intensive behavioral smoking cessation support (very low certainty).
It is very uncertain whether multi‐issue support changes smoking abstinence compared with smoking cessation support only (very low certainty).
Print‐based self‐help probably leads to higher abstinence ‐ non‐tailored self‐help compared with no materials (moderate certainty).
Print‐based self‐help probably leads to higher abstinence ‐ individually tailored self‐help compared with no materials (moderate certainty).
The intervention showed no clear difference in smoking abstinence at longest (low certainty).
It is very uncertain whether the intervention changes relapse prevention at longest (very low certainty).
The intervention showed no clear difference in smoking cessation (moderate certainty).
The intervention showed no clear difference in NRT versus placebo Smoking cessation (low certainty).
The intervention showed no clear difference in bupropion versus placebo Smoking cessation (moderate certainty).
The intervention showed no clear difference in combination NRT & bupropion versus placebo Smoking cessation (low certainty).
The intervention probably leads to higher varenicline versus placebo Smoking cessation (moderate certainty).
Text messaging probably leads to higher long‐term abstinence (all randomised) compared with minimal support (moderate certainty).
The intervention probably leads to higher long‐term abstinence (all randomised) Measured as self‐reported and… (moderate certainty).
It is very uncertain whether smartphone app changes long‐term abstinence (all randomised) compared with lower‐intensity support (very low certainty).
Reduction to quit showed no clear difference in smoking cessation (≥ 6‐month compared with abrupt quitting (moderate certainty).
It is very uncertain whether reduction to quit changes smoking cessation (≥ 6 month compared with no treatment (very low certainty).
Reduction and pharmacotherapy may leads to higher main analysis (all pharmacotherapy): smoking cessation (≥ 6 month compared with reduction alone (low certainty).
Reduction and pharmacotherapy showed no clear difference in subgroup: combination NRT; smoking cessation (≥ 6 month compared with reduction alone (low certainty).
It is very uncertain whether reduction and pharmacotherapy changes subgroup: nicotine patch; smoking cessation (≥ 6 month compared with reduction alone (very low certainty).
Reduction and pharmacotherapy probably leads to higher subgroup: fast‐acting NRT only; smoking cessation (≥ 6 month compared with reduction alone (moderate certainty).