Relapse prevention interventions for smoking cessation
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
The objective of the review is to assess the effectiveness of interventions to reduce or prevent relapse in recent quitters.
Background
Many interventions can help smokers to quit. Both pharmacological approaches, such as nicotine replacement therapy and some antidepressants, and behaviourally focused programmes, have been shown in clinical trials to increase long term quit rates compared to control interventions. Short term quit rates may be high. Amongst smokers motivated to make a quit attempt most can abstain for a day. US data indicate that 41% of current daily smokers have stopped smoking for at least one day in the past year because they are trying to quit. (MMWR 2001). A majority of people in treatment may be able to avoid smoking for a week. But subsequent relapse means that long term rates of sustained abstinence are generally 20% or less even with medication or behavioural support.
Most multi‐session behavioural programmes include 'relapse prevention' components which aim to help smokers identify triggers or high risk situations for relapse and to learn strategies for coping or avoidance. Self‐help manuals generally include tips about the same topics. Pharmacological approaches aim to enhance initial cessation and reduce the likelihood of relapse by reducing withdrawal discomfort and urges to smoke. Interventions generally combine some components intended to promote cessation and some to prevent relapse. Components may also have an impact at multiple places in the quitting process. Consequently it can be difficult to isolate relapse prevention as an area of analysis. Systematic reviews have tended to focus on the long term outcomes and not address the issue of whether the impact has been on the initial quit rates or on reducing relapse.
In evaluating behavioural interventions for relapse prevention two trial designs may be considered. The first focuses very specifically on relapse prevention by recruiting only those smokers who have been able to quit for a period, with or without the use of a particular programme. These participants are randomised to relapse prevention or control interventions. Experimentally this may be the best test of an approach, not least because the power to detect a difference between the groups is maximised. Different studies may use different length of abstinence required in the 'cessation' phase, but this does not detract from the power and clarity of this design. (For example Fortmann and Killen (Fortmann 1995) recruited participants to an identical pre‐cessation programme and randomised those who achieved one day abstinence. By contrast Brandon (Brandon 2000) recruited 'recent quitters', many of whom had been quit for prolonged periods). Interventions which aim to prevent post partum relapse in women who quit smoking during pregnancy may also fall into this group.
The second category of trial addresses relapse prevention indirectly. This type of study compares programmes which use an additional relapse prevention component to programmes without the specific component. Adding relapse prevention components to a programme generally lengthens the period of contact, but studies may control for contact time to identify specific component effects. Some studies may extend contact without specifically identifying the purpose as relapse prevention. This group of studies tend to suffer from low power, as substantial numbers of smokers fail to achieve initial abstinence under either regimen and this tends to mask any effect on those who do quit initially. Including all subjects mixes up long term differences with any differences in short term cessation. Where possible, the analysis should focus on relapse rate in participants who achieved short term abstinence.
Pharmacological interventions for relapse prevention, which may involve extending the course of treatment or changing to a different pharmacotherapy, may also randomise smokers intending to quit or existing quitters. Pharmacotherapy and behavioural interventions may also be combined in ways intended to prevent relapse.
From the perspective of health care providers, knowing the contribution of relapse prevention components is important in deciding 'how much is enough' when offering programmes, and in deciding whether resources are best directed at motivating and supporting smokers in their initial quit attempt, or in trying to prevent later relapse.
Objectives
The objective of the review is to assess the effectiveness of interventions to reduce or prevent relapse in recent quitters.
Methods
Criteria for considering studies for this review
Types of studies
Randomised or quasi‐randomised controlled trials with a minimum follow‐up of six months from quit date.
Types of participants
Recent quitters, or smokers who enrol in a trial of a cessation programme and are abstinent at the end of treatment.
Types of interventions
Interventions identified as intended to prevent relapse, compared to a) no intervention or b) a shorter intervention or c) an intervention not oriented towards relapse prevention. Behavioural interventions may be delivered in any format, including group meetings, face to face sessions and proactive or reactive telephone support. Pharmacological interventions will also be considered.
Types of outcome measures
The preferred outcome will be sustained or multiple point prevalence abstinence at follow‐up of at least 6 months since randomisation. We will compare lapse free and lapse allowed rates where they are both reported. Trials which only report short term point prevalence will be included, but with sensitivity analysis of their impact on the results
Search methods for identification of studies
We will search the Tobacco addiction group trials register which includes the results of comprehensive searches of MEDLINE, PsycINFO and conference abstracts. We will check all trials with 'relapse prevention' in title, abstract or keywords for relevance. In addition we will consider trials included in all other Cochrane reviews of cessation interventions which compare a more with a less intensive intervention.
Data collection and analysis
One author will identify potentially eligible trials for inclusion, and extract data. A second author will duplicate data extraction for included studies and agree the reason for exclusion of other studies.
We will report the following trial characteristics in the Table of Included Studies:
·Country in which study undertaken
·Method of recruitment, and whether smokers or recent quitters randomised.
·Method of randomisation
·Demographics of participants, including age, sex, baseline cigarette consumption, and period of prior quitting if relevant
·Intervention components including number and type of contacts and period of contact
·Control condition(s)
·Outcome, including length of follow‐up, definition(s) of cessation used in review and any other measures used.
·Validation of self reported smoking status, including method used and cut off point for biochemical validation
·Explicit purpose of study
Meta‐analysis
The primary outcome will be the number of quitters at longest follow‐up. Biochemically validated cessation will be used in preference to self report where available. Randomised participants who withdraw, are lost to follow‐up, or fail to provide samples for validation will in general be counted as smokers. Any exceptions to this will be noted and any impact on the results reported. Since relapse prevention may have an effect by preventing lapses leading on to full relapse, we may select both an outcome in which lapses during the intervention are allowed, and one requiring complete abstinence since quit day. In this case we will conduct a sensitivity analysis on the impact of using different definitions of smoking cessation on the pooled results. Where appropriate we will pool study outcomes using a fixed effects (Peto) model. In the event of significant statistical or clinical heterogeneity between trials we will not report pooled estimates.
For trials randomising smokers prior to any intervention we will seek data on the long term cessation rates of the subgroup of participants who had achieved abstinence at the end of treatment, or prior to the relapse prevention component if this involves extended contact. If this is not reported in published papers we will approach authors to request the data.
We will not pool trials which randomise recent quitters with those randomising smokers unless data on short term quitters are available for the latter group of trials. We will consider pooling studies if there is no statistical heterogeneity, but will predefine subgroups based on the type of intervention (mail, telephone, face to face behavioural interventions, exercise, social support, and medication, and pool only within these groups if heterogeneity is found.
We will consider separately any trials randomising smokers, for which data on the subgroup of early quitters cannot be obtained.
Other prespecified subgroups will be trials in pregnant women, and in hospitalised patients. We will include these in the main analyses but in the event of significant heterogeneity we will test the effect of their removal, and we will also report their results separately. As a potential explanation for any heterogeneity we will also distinguish between trials clearly described as addressing relapse prevention in author abstracts and those which we identified as relapse prevention by the intervention content.
