2.23.1 Theoretical basis and utility of the model
The Transtheoretical Model is based on findings in the 1980s that there were differences in the use of specific processes of change by smokers in relation to smoking cessation during periods of decision making, active change and when maintaining change. (160,161). Five experiential processes were predominant when contemplating change: consciousness raising, dramatic relief, environmental re- evaluation, social liberation and self re-evaluation. The use of five behavioural or verbal processes: helping relationships, stimulus control, counter-conditioning, reinforcement management and self-liberation, clustered during active change, although there was a correlation between types of process (162). Individuals not contemplating any behaviour change used fewest processes (163).
The model has also been used to describe change in a variety of other behaviours such as obesity, exercise, mammography screening and illicit drug use (164). There is good evidence for construct validity of the model in smoking cessation and its predictive validity. Cross sectional studies have confirmed that smokers in the stages of precontemplation, contemplation and preparation differ in the
and perceived self-efficacy rather than measures of smoking behaviour (165,166). A mathematical approach has been used to validate the temporal organization of smoking cessation into stages (167,168). Markov chain analysis of shifts between stages, confirm that the event was predicted by the event immediately preceding it. Very importantly, an individual smoker’s position in the stages-of-change model is predictive of smoking cessation success measured later in time for both self-quitters (160) and those receiving smoking cessation interventions (166,167).
2.23.1 Description of model
The number of stages in the model and its division into time periods has varied since the initial, early description. However, as described more recently, five stages are identified and defined in a temporal order (Figure 2.2)(167).
1. Precontemplation: a period in which smokers are not thinking about quitting smoking (at least not in the next six months).
2. Contemplation: a period of time in which smokers are seriously thinking about quitting in the next six months
3. Preparation: a period when smokers who have tried to quit smoking in the past year seriously think about quitting in the next month.
4. Action: a period ranging up to six months after smokers have made an overt change and stopped smoking.
5. Maintenance: a period beginning six months after cessation and continuing until smoking is terminated as a problem.
Figure 2.2: A diagrammatic representation of the five stages in the Transtheoretical Model of smoking cessation.
2.23.3 Using the model to design interventions for smoking cessation
The Transtheoretical Model has been used extensively to guide smoking cessation interventions that are tailored to a specific stage of change (167,169-172). There is some controversy over this elevation of a structural model to the theory level (173) and a systematic review of the effectiveness of stage-based interventions to promote smoking cessation concluded that stage-based interventions are no more effective than non-stage based interventions or no intervention in changing smoking behaviour (174).
2.23.4 Factors affecting the stage of readiness to quit
A smoker’s stage of readiness to quit is affected by many factors: social, behavioural and psychological. In a study of smokers (n=506) attending a health maintenance organisation in the USA (175), the likelihood of being in a higher level of readiness to quit was greater for those who smoked fewer cigarettes per day and those who attributed symptoms to smoking. Age was not significantly associated with stages of change. Smokers who perceived very important health benefits compared to fewer benefits from quitting smoking and those who perceived that others wanted them to quit smoking very much were also more likely to be in a higher stage of readiness. In a study in primary care in the UK, smokers were surveyed on their respiratory symptoms, smoking behaviour, quit attempts, self-efficacy and recall of smoking cessation advice. Those with one or more symptoms, who attributed them to smoking, were eight times more likely to believe that their health would improve if they stopped smoking and six times more likely to intend to stop smoking (176). In a study in the Netherlands in 633 patients with COPD, those in the stages of contemplation/preparation had significantly greater expectations of improved health from quitting and greater social support for quitting from significant people in their lives than those in precontemplation (177).
2.23.5 Self-efficacy and smoking cessation
According to the Social Cognitive Theory of Bandura (155,178), significant differences are expected between self-efficacy levels for individuals in subsequent stages from contemplation to maintenance. There is evidence confirming this in a number of different settings, with later stages having the highest self-efficacy expectations toward non-smoking among smokers in the general community (179)
interventions. In smokers with low readiness to change, an increase in self-efficacy scores occurred when quit information was given. The effects were significantly greater after receiving multiple letters, individually tailored to the stage of change, compared to a single tailored letter or a self-help guide (169). The level of self- efficacy of an individual also predicts actual quitting in unselected smokers (180,181) and smokers with COPD (182).