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NICE Underpinning Review
Aims of the review: To determine the effectiveness of long-term harm reduction approaches without the prior intention of quitting (ie reducing consumption without the aim of quitting), with and without assistance.
Overall, the evidence within the review suggests that:
Across all studies of NRT versus placebo where reduction is an intended outcome, meta-analyses indicate significant benefits from NRT.
NRT may also be effective for abstinence in the longer term in populations not looking to quit.
NRT supplementation may help reduce ad libitum smoking (where there is no instruction to reduce) but the evidence base is weak.
No evidence comparing combinations of NRT was found but it appears that there are no clear differences in effectiveness between different types of medication and some modest evidence that offering smokers a choice of medication may enhance efficacy.
Nicotine patch is effective in reducing post-operative smoking consumption in the short term but this is not maintained long term.
Evidence for the value of e-cigarettes to date is available only from a single UBA study and, although suggestive of benefit, no conclusions can be drawn as yet. We note that the MHRA is currently considering whether to regulate e-cigarettes and other nicotine-containing products.
Two studies suggest NRT combined with a brief motivational component may be effective for abstinence in populations not looking to quit. However, the impact of the motivational component is unclear.
There is consistent evidence that motivational interviewing alone, either in single or multiple sessions, is not effective as a long-term harm reduction strategy.
MI does not appear to be effective for abstinence in populations unable or unwilling to quit. This is at variance with the evidence from a Cochrane systematic review looking at the effect on abrupt cessation (Lai 2010); which found some evidence that MI may assist abstinence. The reason for this variance is not clear, although it may reflect the impact of the two statistically significant studies - Hollis 2007 and Soria 2006. In the first, which contributed considerable weight to pooled analyses, study participants had to be motivated to quit. In the second study bupropion was provided to a small proportion of the MI group, which may have skewed the results.
The evidence available for other types of behavioural intervention is weaker but it is also suggestive of no benefit. Both brief and intensive pre-operative smoking interventions, combining counselling with NRT, increase smoking cessation at the time of surgery. However only intensive interventions were effective long term.
There is no evidence of effect on parental smoking levels from interventions to reduce environmental tobacco smoke. Results do not appear to vary between parents of asthmatics and those with generally healthy children.
No evidence was found to suggest an optimal reduction period.
Limited weak evidence suggests that scheduled smoking reduction may be more effective than non-scheduled smoking reduction; although there do not appear to be differences in effect between types of scheduled reduction.
There is very little evidence to distinguish the effectiveness of interventions across socio-economic groups.The small amount of evidence available suggests that harm reduction interventions do not deter smokers from wishing to quit. More evidence of smokers’ views is likely to be provided within the barriers and facilitators review (Review 4).
Longer-term NRT use appears to be well tolerated over periods between six months and five years with severe side effects being relatively rare.
Further research is needed in a number of areas: the differential effects for socio-economic and ethnic groups, the impact of different NRT combinations and the efficacy of e-cigarettes, the effect of intensity of the intervention.