Stages and processes of change as predictors of drug use among methadone maintenance patients.

In this study the authors evaluated the predictive validity of stages-of-change and processes-of- change measures among methadone maintenance patients. One month after treatment entry, participants completed questionnaires providing stage and process scale scores regarding readiness to discontinue polydrug use. Participants also completed an algorithm assigning them to a stage category on the basis of their stated intentions regarding quitting. The algorithm predicted urinalysis results during a 12-week posttest period; however, only 1 stage scale (contemplation) and no process scales correlated significantly with outcome. In a hierarchical regression, stage and process scale scores significantly improved prediction of posttest abstinence beyond that afforded by baseline drug-free urine rates, but this effect was attributable to the contemplation scale alone. Despite their widespread use, stage and process scales have yet to demonstrate clearly predictive validity.