Dynamic typology clustering within the stages of change for smoking cessation.

Dynamic typology clustering was employed to find homogeneous subgroups of smokers within each of three early stages of change (precontemplation, contemplation, preparation) in a representative sample of smokers. Individual change profiles were created by coding the stage of change for each subject at five consecutive assessment points over a 2-year period (baseline and 6, 12, 18, and 24 months). A total of 446 unique change profiles were found in the sample of 2,088 smokers who had complete data for all five time points. The sample was initially split into three groups determined by baseline stage of change. Within each initial stage, subgroups that shared similar patterns of change were interpreted by examining the shape and elevation of the change profiles. Four major types of profiles emerged: a stable profile, a progressing profile, a vacillating profile, and a regressing profile. External validation revealed significant differences among the dynamic typology subtypes on key transtheoretical model constructs (processes of change, decisional balance, situational temptations). These results both support and complement key construct relationships within the transtheoretical model and can provide important predictive information to direct and enhance treatment interventions for smoking cessation.