The standard way most people are advised to stop smoking is by quitting abruptly on
a designated quit day. However, many people who smoke have tried to quit many times
and may like to try an alternative method. Reducing smoking behaviour before quitting
could be an alternative approach to cessation. However, before this method can be
recommended it is important to ensure that abrupt quitting is not more effective than
reducing to quit, and to determine whether there are ways to optimise reduction methods
to increase the chances of cessation. To assess the effect of reduction‐to‐quit interventions
on long‐term smoking cessation. We searched the Cochrane Tobacco Addiction Group Specialised
Register, MEDLINE, Embase and PsycINFO for studies, using the terms: cold turkey,
schedul*, cut* down, cut‐down, gradual*, abrupt*, fading, reduc*, taper*, controlled
smoking and smoking reduction. We also searched trial registries to identify unpublished
studies. Date of the most recent search: 29 October 2018. Randomised controlled trials
in which people who smoked were advised to reduce their smoking consumption before
quitting smoking altogether in at least one trial arm. This advice could be delivered
using self‐help materials or behavioural support, and provided alongside smoking cessation
pharmacotherapies or not. We excluded trials that did not assess cessation as an outcome,
with follow‐up of less than six months, where participants spontaneously reduced without
being advised to do so, where the goal of reduction was not to quit altogether, or
where participants were advised to switch to cigarettes with lower nicotine levels
without reducing the amount of cigarettes smoked or the length of time spent smoking.
We also excluded trials carried out in pregnant women. We followed standard Cochrane
methods. Smoking cessation was measured after at least six months, using the most
rigorous definition available, on an intention‐to‐treat basis. We calculated risk
ratios (RRs) and 95% confidence intervals (CIs) for smoking cessation for each study,
where possible. We grouped eligible studies according to the type of comparison (no
smoking cessation treatment, abrupt quitting interventions, and other reduction‐to‐quit
interventions) and carried out meta‐analyses where appropriate, using a Mantel‐Haenszel
random‐effects model. We also extracted data on quit attempts, pre‐quit smoking reduction,
adverse events (AEs), serious adverse events (SAEs) and nicotine withdrawal symptoms,
and meta‐analysed these where sufficient data were available. We identified 51 trials
with 22,509 participants. Most recruited adults from the community using media or
local advertising. People enrolled in the studies typically smoked an average of 23
cigarettes a day. We judged 18 of the studies to be at high risk of bias, but restricting
the analysis only to the five studies at low or to the 28 studies at unclear risk
of bias did not significantly alter results. We identified very low‐certainty evidence,
limited by risk of bias, inconsistency and imprecision, comparing the effect of reduction‐to‐quit
interventions with no treatment on cessation rates (RR 1.74, 95% CI 0.90 to 3.38;
I 2 = 45%; 6 studies, 1599 participants). However, when comparing reduction‐to‐quit
interventions with abrupt quitting (standard care) we found evidence that neither
approach resulted in superior quit rates (RR 1. 01, 95% CI 0.87 to 1.17; I 2 = 29%;
22 studies, 9219 participants). We judged this estimate to be of moderate certainty,
due to imprecision. Subgroup analysis provided some evidence (P = 0.01, I 2 = 77%)
that reduction‐to‐quit interventions may result in more favourable quit rates than
abrupt quitting if varenicline is used as a reduction aid. Our analysis comparing
reduction using pharmacotherapy with reduction alone found low‐certainty evidence,
limited by inconsistency and imprecision, that reduction aided by pharmacotherapy
resulted in higher quit rates (RR 1. 68, 95% CI 1.09 to 2.58; I 2 = 78%; 11 studies,
8636 participants). However, a significant subgroup analysis (P < 0.001, I 2 = 80%
for subgroup differences) suggests that this may only be true when fast‐acting NRT
or varenicline are used (both moderate‐certainty evidence) and not when nicotine patch,
combination NRT or bupropion are used as an aid (all low‐ or very low‐quality evidence).
More evidence is likely to change the interpretation of the latter effects. Although
there was some evidence from within‐study comparisons that behavioural support for
reduction to quit resulted in higher quit rates than self‐help resources alone, the
relative efficacy of various other characteristics of reduction‐to‐quit interventions
investigated through within‐ and between‐study comparisons did not provide any evidence
that they enhanced the success of reduction‐to‐quit interventions. Pre‐quit AEs, SAEs
and nicotine withdrawal symptoms were measured variably and infrequently across studies.
There was some evidence that AEs occurred more frequently in studies that compared
reduction using pharmacotherapy versus no pharmacotherapy; however, the AEs reported
were mild and usual symptoms associated with NRT use. There was no clear evidence
that the number of people reporting SAEs, or changes in withdrawal symptoms, differed
between trial arms. There is moderate‐certainty evidence that neither reduction‐to‐quit
nor abrupt quitting interventions result in superior long‐term quit rates when compared
with one another. Evidence comparing the efficacy of reduction‐to‐quit interventions
with no treatment was inconclusive and of low certainty. There is also low‐certainty
evidence to suggest that reduction‐to‐quit interventions may be more effective when
pharmacotherapy is used as an aid, particularly fast‐acting NRT or varenicline (moderate‐certainty
evidence). Evidence for any adverse effects of reduction‐to‐quit interventions was
sparse, but available data suggested no excess of pre‐quit SAEs or withdrawal symptoms.
We downgraded the evidence across comparisons due to risk of bias, inconsistency and
imprecision. Future research should aim to match any additional components of multicomponent
reduction‐to‐quit interventions across study arms, so that the effect of reduction
can be isolated. In particular, well‐conducted, adequately‐powered studies should
focus on investigating the most effective features of reduction‐to‐quit interventions
to maximise cessation rates. Can people stop smoking by cutting down the amount they
smoke first? Background The standard way people are told to quit smoking is to smoke
as normal until a quit day, when they stop using all cigarettes. However, many have
tried this before and might like to try something new. Some people would just prefer
to cut down the amount of cigarettes they smoke before quitting completely. Before
healthcare services give people a choice of cutting down first or stopping all at
once we need to find out whether cutting down helps as many people to stop smoking.
There are different ways that people could reduce the amount they smoke (for example,
setting goals, lengthening the time between cigarette breaks) and some of these may
work better than others. This review looks at whether cutting down before quitting
helps people to stop smoking, and the best ways that people can cut down to help them
stop completely. Study characteristics This review includes 51 studies of over 22,000
people who smoked tobacco. Most were adults, and people typically smoked at least
23 cigarettes a day at the start of the studies. All studies included at least one
group of people who were asked to cut down their smoking and then quit tobacco smoking
altogether. This group was compared to either a group who did not receive any treatment
to stop smoking, a group who were asked to stop smoking all at once, or a group who
were also asked to cut down their smoking in a different way. We did not include studies
which asked people to cut down without quitting. Studies lasted for at least six months.
The evidence is up to date to October 2018. Key results There was not enough information
available to decide whether cutting down before quitting helped more people to stop
smoking than no stop‐smoking treatment. However, people who were asked to stop smoking
all of their cigarettes at once were not more likely to quit than people who were
asked to cut down their smoking before quitting. This suggests that asking people
to cut down their smoking first may be a useful way to help people to stop smoking.
People who cut down their smoking while using varenicline or a fast‐acting form of
nicotine replacement therapy (NRT), such as gum or lozenge, may be more likely to
quit smoking than people who cut down their smoking without using a medicine to help
them. Giving people face‐to‐face support to cut down their smoking may help more people
to quit than if they are provided with self‐help materials to cut down by themselves.
There was not enough information available to decide whether other features of the
cutting‐down‐to‐quit intervention improved people's chances of stopping smoking. We
looked at whether being asked to cut down smoking before quitting resulted in negative
effects, such as cigarette cravings, difficulty sleeping, low mood or irritability.
Most studies did not provide information about this; more studies are therefore needed
to answer this question. Quality of the evidence There is very low‐quality evidence
looking at whether cutting down smoking before quitting helps more people to quit
smoking than no treatment. We rated the quality as very low, as there were problems
with the design of studies, findings of studies were very different from one another,
and not enough people took part, making it difficult to tell whether cutting down
helps people to quit smoking. However, there is moderate‐certainty evidence that cutting
down before quitting may result in similar quit rates to quitting all at once, which
suggests that cutting down may be a helpful approach. We rated this evidence as moderate
because there is a chance that future studies may find that cutting down helps slightly
more or slightly fewer people to quit than when people quit all at once. There is
also moderate‐quality evidence that people may be more likely to quit by cutting down
first when they use a stop‐smoking medicine like varenicline or a type of fast‐acting
NRT to help them. We rated this evidence as moderate certainty because there were
not enough people taking part; more studies are needed.