Summary of findings 4. Longer compared to shorter duration of nicotine patch therapy for smoking cessation.

Longer compared to shorter duration of nicotine patch therapy for smoking cessation
Patient or population: people who smoke Setting: any; studies conducted in: Europe, USA Intervention: longer duration of nicotine patch therapy (weeks) Comparison: shorter duration of nicotine patch therapy (weeks)
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with shorter‐duration patch	Risk with longer‐duration patch
Smoking cessation	Study population		n/a	7078 (7 RCTs)	⊕⊕⊝⊝ Lowa,b,c	We did not pool studies, due to substantial clinical heterogeneity in length of intervention and control patch duration, and two studies appeared in multiple comparisons. None of the individual comparisons detected a statistically or clinically significant difference between longer and shorter durations of patch therapy.
	n/a	n/a
Overall serious adverse events	Study population		n/a	1173 (3 RCTs)	⊕⊝⊝⊝ Very lowb,d	We did not pool studies, due to substantial clinical heterogeneity in length of intervention and control patch duration, and one study appeared in multiple comparisons. We found no significant differences in any study.
	n/a	n/a
Treatment withdrawals	n/a		n/a	648 (2 RCTs)	⊕⊝⊝⊝ Very lowb,d	We did not pool studies, due to substantial clinical heterogeneity in length of intervention and control patch duration. We found no significant differences in any study.
	n/a	n/a
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). n/a: not applicable; RCT: randomised controlled trial
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

^aDowngrade by one level due to imprecision: all individual comparisons had fewer than 300 events overall.
^bDowngrade by one level due to inconsistency: clinical heterogeneity between treatment durations in individual studies prevented pooling.
^cMost studies were at a high risk of bias for blinding, but as studies did not detect significant effects, we think blinding was unlikely to have contributed to the outcome.
^dDowngraded by two levels due to imprecision: fewer than 100 events overall.