The stages and processes of change for smoking cessation, testing the transtheoretical model

Abstract

Cigarette smoking has had a devastating impact on the health of Canadians for decades. Few smokers try to quit; of those who make an attempt, the vast majority fail to remain smoke-free beyond a short period. The purpose of this thesis was to critically evaluate the empirical support for the Transtheoretical Model (TTM), and extremely popular and relatively recent theory that has promised to provide a revolutionary approach to smoking cessation (Prochaska, DiClemente, & Norcross, 1992). The TTM proposes that smoking cessation is a complex process that requires movement through a series of stages of readiness to change rather than a simple shift from smoking to non-smoking. It proposes that smokers in each of the stages have unique thoughts, feelings, and behaviours relevant to their smoking and, b y implication, have different intervention needs. The TTM maintains that smoking-cessation programs built around "processes of change" that are matched or targeted to the needs of each stage will lead to greater change than is presently obtained by current, non-targeted approaches. The critical review of the TTM literature in this thesis, however, identified substantial gaps in its conceptual and scientific foundations. Conceptually, the model's structure has been presented in a vague and imprecise manner that does not provide clear guidance to other researchers. In addition, the main tenets of the model - that smokers i different stages use different processes of change, and that smokers in different stages need to apply different processes in order to maximize their outcomes - have either been untested, or have received little support. This thesis provided a comprehensive account of the structure of the model and its claims, and the appropriate analytic strategies for testing those claims. Using a longitudinal survey study of 386 smokers, this thesis provided the first focused tests of the main tenets of the model. The claim that smokers in different stages use different processes of change was completely unsupported; instead, primarily quantitative distinctions among the stages on their use of the processes were observed. The claim that smokers in different stages need to use different processes received partial support; while there was some indication that the processes' effects varied by stage, these effects were not as differentiated as claimed by the proponents of the TTM. The implications of these findings for the model, and for interventions based jupon its principles, were fully explored with the goal of identifying ways to improve the empirical foundations of the model to permit its responsible use by health care practitioners.