Systematic review of the effectiveness of stage based interventions to promote smoking cessation

Several intervention approaches have been looked at to help smokers
quit smoking during the last decade. Because all interventions are not
designed or conducted in similar manner, it is important to think through
these efforts before the research community discards or accepts one type
of intervention. Riemsma et al found limited effectiveness of stage-based
interventions in smoking cessation 1. However, important flaws in the
review process limit their conclusions.

First, they included studies which examined the effectiveness of
stage based interventions in influencing behaviour, but Prochaska's stage
of change construct has been validated as an approach for managing
behaviour change not as an event, but rather as a process 2. Furthermore,
behaviour change could be defined in many ways such as quitting smoking or
reducing smoking or making more quitting attempts or changing to
occasional smoker. It was not clear how the authors dealt with these
results, which are often discussed as secondary outcomes in the discussion
part of published reports. Authors' inclusion only of primary outcomes
might have led to these being missed.

Second, the process of intervention delivery can affect the outcome.
Many studies, which are designed not to deliver stage-based interventions,
may actually end up giving stage-based interventions indirectly. Because
interventions are provided with a focus on motivation to quit or directly
to change behaviour (i.e. quit smoking), which is also a component of
Prochaska's transtheoretical model. Not reporting such information does
not necessarily explain the ineffectiveness of a study.

Third, the review process was too rigorous. The authors set up too
many criteria (18 variables) to evaluate the studies. It is certain that
the more rigorous the review, the less evidence there will be that the
intervention is effective 3. Making conclusions based on a few unmet
criteria could be misleading. However, one important criterion, adherence
to stage-based smoking cessation interventions was missed, but it could
have provided useful information about the outcome. There is evidence that
non-adherence to interventions could result in a poor outcome4. I would
argue that future trials on smoking cessation should assess and report
information on adherence to the intervention to help evaluate the
effectiveness of interventions.

While I commented the authors' efforts to look at the evidence on
stage-based smoking cessation interventions, their conclusion could
prejudice researchers and service providers against the substantial
evidence accumulated over the last decade that stage-matched intervention
is effective. This may also reduce the motivation of medical
professionals, who are already reluctant to give advice to smoker patients
to quit smoking. Professionals should remember that absence of clear
evidence from systematic reviews does not mean that inertia is the
recommended course of action 3, and should continue to use every
opportunity to promote smoking cessation as recommended in the United
States Clinical practice guidelines: Treating Tobacco Use and Dependence
5.

References:
1. Riemsma RP, Pattenden J, Bridle C, Sowden AJ, Mather L, Watt IS,
Walker A. Systematic review of the effectiveness of stage based
interventions to promote smoking cessation. BMJ 2003; 326: 1175-1177.

2. Joseph J, Breslin C, Skinner H. Critical perspectives on the
transtheoretical model and the stages of change. In: Tucker JA, Donovan
DM, Marlatt GA (Eds). Changing addictive Behaviour: Bridging clinical and
public health strategies, 1999, pp 160-180. Guildford press: New York.

3. Petticrew M. Why certain systematic reviews reach uncertain
conclusions. BMJ 2003; 326: 756-8.

4. Haynes RB, Dantes R. Patient compliance in the design and
interpretation of clinical trials. Control Clin Trial 1987; 8:12-19

5. Public Health Service. Clinical practice guideline: Treating
tobacco use and dependence. US Department of Health and Human Services,
USA June 2000 (ISBN 1-58763 007 9).

Competing interests:  
None declared