| Study | Reason for exclusion |
|---|---|
| ACTRN12612001210864 | All arms received the same NRT and instructions, but some were told that there were benefits of long‐term NRT use. Therefore, between‐group differences were purely in the information provided. |
| Aubin 2006 | Short‐term experimental cross‐over study of the effect of different types of nicotine patch on sleep and smoking urges. Abstinence not measured and length of follow‐up too short |
| Baker 2021 | Despite the factorial study design, an intervention component (varenicline duration) was not balanced between studies arms with varying durations of NRT use. |
| Berlin 2012 | Main comparator was the elective monoamine oxidase (MAO)‐B inhibitor, EVT 302. Groups receiving NRT received the same dosing and administration across groups |
| Carpenter 2011 | Measured effect of providing NRT samples on participants not initially motivated to quit. Participants were encouraged but not required to make a practice quit attempt. Intervention participants were provided with up to 2 boxes of nicotine lozenges. |
| Chan 2010 | Measured effect of counselling plus 2 weeks of free NRT. No data on whether control group also used NRT; unclear if outcome due to counselling or free NRT |
| Cook 2016 | Participants were not motivated or were unwilling to quit at recruitment, or both. |
| Cook 2021 | Participants were not motivated or were unwilling to quit at recruitment, or both. |
| Dey 1999 | Compared free and paid prescription for nicotine patch. Only 14 weeks follow‐up |
| Etter 2009 | Differences in the behavioural intervention (not just NRT) between arms, making it impossible to attribute any effect to use of NRT. For this reason, the study does not meet review inclusion criteria. It was included in Stead 2012, but has been removed for this update. |
| Fagerström 1993 | Short‐term cross‐over trial. Endpoint was withdrawal symptoms not cessation |
| Fagerström 1997 | Short‐term cross‐over trial of different types of NRT. For 2 weeks, participants could choose a method; for other 2 weeks, they were randomly assigned to 1 of gum, patch, spray, inhaler or tablet. Smoking reduction assessed |
| Fagerström 2000 | Short‐term cross‐over trial comparing 2 nicotine delivery devices |
| Ferguson 2015 | Standard nicotine patch treatment versus pre‐quit patch versus varenicline. Follow‐up of fewer than 6 months (10 weeks) |
| Hajek 1999 | Follow‐up of fewer than 6 months. There were no significant differences in 12‐week abstinence rates between gum, patch, spray or inhaler groups. |
| Haustein 2003 | Trial of nicotine gum for smoking reduction in people not making a quit attempt. See Cochrane Review of harm reduction interventions (Lindson‐Hawley 2016) |
| Hollands 2013 | Intervention was informing participants that their oral NRT dose was matched to their phenotype versus genotype; NRT dose was actually the same across groups |
| Hughes 1989 | No long‐term follow‐up; primarily a trial of the effect of instructions |
| Hughes 2010 | Differences in the behavioural intervention (not just NRT) between arms, making it impossible to attribute any effect to use of NRT. For this reason, study does not meet review inclusion criteria. It was included in Stead 2012, but has been removed for this update. |
| Jibrail 2010 | Only 12 weeks of follow‐up. Study of NRT for smoking abstinence and relationship between C‐reactive protein and depressed mood during nicotine abstinence |
| Kozak 1995 | Open‐label study in which smokers with higher nicotine dependence scores were given higher patch doses |
| Kras 2010 | Study of NRT and Hypericum perforatum (St. John's wort) extract. Only 10 weeks of follow‐up |
| Landfeldt 1998 | Only 12 weeks of follow‐up reported in abstract. No evidence of benefit from combining patch and nasal spray compared to nasal spray alone |
| Leischow 1999 | Behavioural support differed between arms, confounding effect of NRT |
| Leischow 2004 | Behavioural support differed between arms, confounding effect of NRT |
| Lu 2017 | Pre‐quit nicotine patch versus standard patch versus varenicline. Follow‐up of fewer than 6 months (4 weeks) |
| Marsh 2005 | Only 3 months of follow‐up; safety study comparing 4 mg lozenge to 4 mg gum |
| McNeil 2007 | Only 3 months of follow‐up. Comparison of patch and nasal spray (n = 51) versus nasal spray alone (n = 50). Sustained abstinence rates 18% in each group. Used in a sensitivity analysis of combination therapies |
| McRobbie 2010 | Short‐term cross‐over study assessing withdrawal symptoms and user satisfaction |
| Minneker 1989 | Only 9 weeks of follow‐up |
| NCT00985985 | 4‐arm study of 2 mg lozenge versus placebo and 4 mg lozenge versus placebo. However, participants were not randomised to 4 mg or 2 mg lozenge; rather, low‐dependency smokers were allocated to 2 mg lozenge and high‐dependency smokers were allocated to 4 mg lozenge. |
| NCT01592695 | Participants received tailored pharmacotherapy in both study arms. The intervention being tested was the type of behavioural support. |
| NCT01892813 | Participants received tailored pharmacotherapy in both study arms. The intervention being tested was the type of behavioural support. |
| NCT02147132 | Has study arms allowing comparison of standard NRT use and long‐term NRT use; however, only short‐term follow‐up planned (8 weeks) |
| NCT02271919 | Has study arms allowing comparison of combination versus single‐form NRT; however, only short‐term follow‐up planned (12 weeks) |
| NCT04946825 | No eligible comparator as NRT components matched between study arms |
| Oncken 2009 | Study of short‐term effects (4 days) of NRT (nicotine patch and nicotine nasal spray) in pregnant smokers |
| Pomerleau 2003 | Compared extended treatment (18 weeks) to 10‐week treatment with nicotine patch. No follow‐up beyond 18 weeks |
| Sachs 1995 | Only 6 weeks of follow‐up |
| Schneider 2004 | Short‐term cross‐over study testing 5 nicotine treatments. Participants used each medication on rising for half a day and resumed smoking each afternoon. |
| Schneider 2008 | Outcome was craving and withdrawal, not abstinence |
| Shahab 2011 | Short‐term cross‐over trial of withdrawal symptom relief |
| Shiffman 2000a | Compared 10 and 6 weeks of patch treatment without longer follow‐up. Main outcome was craving and withdrawal |
| Shiffman 2000b | Comparison between 24‐hour and 16‐hour patches. Assessment of craving and abstinence over 2 weeks |
| Shiffman 2002 | Not a randomised trial. Compared prescription and over‐the‐counter patch in different populations using different methods |
| Sutherland 1999 | Only 3 months of follow‐up. Comparison of patch and nasal spray (n = 104) versus patch alone (n = 138) or nasal spray alone (n = 138). Used in a sensitivity analysis of combination therapies |
| Tundulawessa 2010 | Only 4 weeks of follow‐up |
| Vikhireva 2003 | Trial of free choice of NRT product versus assigned NRT product; no control group |
| Vinci 2021 | Participants were not motivated to quit |
| Williams 2007 | Only short‐term outcomes reported in conference abstract. Trial terminated early when no benefit of higher dose detected in interim analysis |
| Wright 2018 | Ineligible intervention |
NRT: nicotine replacement therapy