Behavioral interventions and cost-effectiveness analysis.

Behavioral health interventions are often gauged with a dichotomous outcome, "success" or "failure." Hidden by this dichotomy is a series of behavior changes that can be followed with the Transtheoretical Model (stages of change). There has been little consideration, however, about whether this information can and should be used in cost-effectiveness analysis. We review the stages of change model and its applications to behavioral health interventions. We then discuss analytical methods for including stages of change, or similar behavior change models, in cost-effectiveness analysis (CEA). This is typically not done but it may be critical for study design and for interpreting CEA results.