Predictive validity of single-item motivational measures for emerging adults in substance-use disorder treatment

Objective: Few studies have examined which measures of motivation for change predict abstinence and early remission outcomes (AER) for emerging adults with substance-use disorders, and recent research suggests that single-item measures may perform as well as longer readiness-to-change scales. This study extends findings to emerging adults (ages 18–25) treated in outpatient settings by investigating the predictive validity of a single-item motivational measure. Method: Using a national data set of emerging adults receiving outpatient substance-use disorder treatments (N = 1,951), we predicted AER at 3 and 6 months in logistic regression models that controlled for demographics, global severity, and baseline values of the dependent variable. Separate models were run based on self-reported quit status at intake, and all models were corrected for site differences. Results: The single-item motivational measure significantly predicted AER status for quitters at both 3 and 6 months and for nonquitters at 6 months. Conclusions: The single-item motivational measure was the only motivation measure to predict 3- and 6-month outcomes. Thus, it could be used in many situations, except when researchers are interested in clarifying theoretical considerations pertaining to motivation.