Back to the drawing board? A review of applications of the transtheoretical model to substance use

The transtheoretical model (TTM) is still enormously popular with practitio ners, clinicians and many researchers in the addictions field. However, in a recent years a number of commentators have criticized aspects of the mode l and the research based on it. This paper extends a recent critique of the TTM as applied to smoking cessation to include applications of the model t o cessation or reduction of alcohol or drug use. The first section discusse s measures of the central construct of stages of change and notes a number of serious problems. Staging algorithms are based on arbitrary rime periods and some are logically flawed. In the case of multi-dimensional questionna ires (the URICA, the SOCRATES and the RCQ), the pattern of correlations amo ng the subscales shows that they are nor measuring discrete stages of chang e. The one study to date that has compared the two different methods found low concordance, which is probably due to incompatible stage definitions. I n the second section of the paper, the evidence base for the TTM is reviewe d. The review is organized by the four research designs that have been used to rest predictions from stage models: cross-sectional comparisons of peop le in different stages; examination of stage sequences; longitudinal predic tion of stage transitions; and experimental studies of matched and mismatch ed interventions. it concludes that current evidence for the model as appli ed to substance use is meagre and inconsistent. Researchers are urged to de velop better stage models.