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Time for a change: putting the Transtheoretical (Stages of Change) Model to rest


The Transtheoretical Model of behaviour change, known to many as the Stages of Change (SOC) model, states that with regard to chronic behaviour patterns such as smoking, individuals can be characterized as belonging to one of five or six 'stages' (Prochaska et al . 1985; Prochaska & Goldstein 1991; Prochaska & Velicer 1997).

Stage definitions vary from behaviour to behaviour and across different versions of the model but in the case of smoking: 'precontemplation' involves an individual not thinking about stopping for at least 6 months; 'contemplation' involves an individual planning to stop between 31 days and 6 months, or less than 31 days if they have not tried to quit for 24 hours in the past year; 'preparation' involves the individual having tried to stop for 24 hours in the past year and planning to stop within 30 days (it has been accepted by the proponents of the model that having tried to stop should perhaps be dropped from this stage definition); 'action' involves the individual having stopped for between 0 and 6 months; 'maintenance' involves the individual having stopped for more than 6 months.

In some versions of the model there is also a 'termination' stage in which the individual has permanently adopted the new behaviour pattern.

The model further proposes that individuals progress through stages sequentially but usually revert to prior stages before achieving maintenance and then termination (Prochaska & Velicer 1997).

The model also proposes that different self-change strategies (the so-called 'processes of change') are involved in moving between different stages (Prochaska & Velicer 1997) and that the different stages are associated with different beliefs (assessment of the 'pros' and 'cons' of the behaviour and self-confidence in ability to change the behaviour).

Intervention should be stage appropriate

It argues that interventions to promote change should be designed so that they are appropriate to an individual's current stage (Prochaska & Goldstein 1991). Moving an individual from one stage to another is purported to be a worthwhile goal because it will increase the likelihood that this person will subsequently achieve the termination stage (Prochaska & Goldstein 1991).

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Proponents of the model have argued that the model has revolutionized health promotion, claiming that interventions that are tailored to the particular stage of the individual improve their effectiveness (Prochaska & Velicer 1997).

There are serious problems with the model, many of which have been well articulated (Etter & Perneger 1999; Bunton et al . 2000; Whitelaw et al . 2000; Sutton 2001; Etter & Sutton 2002; Littell & Girvin 2002). However, its popularity continues largely unabated.

This editorial does not seek to revisit the plethora of empirical evidence and conceptual analysis that has been ranged against the model. It simply argues that the problems with the model are so serious that it has held back advances in the field of health promotion and, despite its intuitive appeal to many practitioners, it should be discarded.

It is now time for a change. A replacement is needed that more accurately reflects observations about behaviour change, is internally consistent, and generates useful ideas and predictions.

It needs to provide a way of describing how people can change with apparent suddenness, even in response to small triggers. It needs to be a stimulus to research that will go beyond a simplistic decision-making model of behaviour and produce genuinely novel insights.

However, even in the absence of a new theory, simply reverting to the common sense approach that was used prior to the Transtheoretical Model would better than staying with the model. In that approach people were asked simply about desire to change and ability to change and it was recognized that these were affected by a range of personal and situational factors including addiction.

This editorial draws primarily from research in smoking. It is in this area that the model was first developed and where much of the research relating to it has been carried out.

To give some idea of the extent of the dominance of smoking, of 540 articles found in PubMed using the search phrase 'stages of change', 174 also had 'smoking' in the abstract or title, 60 had 'alcohol', seven had cocaine, two had 'heroin' or 'opiate' and one had 'gambling'.

Problems with the transtheoretical model

First of all the model is flawed even in its most basic tenet, the concept of the 'stage'. It has to draw arbitrary dividing lines in order to differentiate between the stages. This has to mean that these are not genuine stages.

For example, an individual who is planning to stop smoking is in the preparation stage if this is within the next 30 days (provided that the smoker has made a quit attempt that lasted 24 hours in the past 12 months) but only the contemplation stage if it is in 31 days' time (Sutton 2001).

Boundaries between so-called 'stages' are therefore simply arbitrary lines in the sand and statements of the kind 'xx per cent of smokers are in the "contemplation stage"' have little useful meaning. They should not be taken to mean, as they so often are, that 'xx per cent of smokers are thinking about stopping smoking'.

Secondly, this approach to classifying individuals assumes that individuals typically make coherent and stable plans. People responding to multiple-choice questionnaires are compliant and will generally try to choose an answer, but this does not mean that they think about things in the terms set by the response options.

Apart from those individuals that set a specific occasion or date for change (e.g. in a New Year's resolution), intentions about change appear to be much less clearly formulated. In what appears to be the first study of its kind, Larabie (in press) found that more than half of reported quit attempts in a general practice sample involved no planning or preparation at all-not even going so far as to finish the current packet of cigarettes.

Another recent study found considerable instability in intentions to stop smoking over short periods (Hughes et al. in press). A high level of instability in stages has also been found in other domains (De Nooijer et al . 2005).

Thirdly, it has been pointed out by others that the stage definitions represent a mixture of different types of construct that do not fit together coherently (e.g. time since quit, past quit attempts and intention) (Etter & Sutton 2002). It is not, as some of those using the model would like it to be, a statement of 'readiness' to change. Readiness or even preparedness is not actually assessed.

Fourthly, the model focuses on conscious decisionmaking and planning processes and draws attention away from what are known to be important underpinnings of human motivation.

It neglects the role of reward and punishment, and associative learning in developing habits that are hard to break (Baumeister et al . 1994; Mook 1996; Salamone et al . 2003).