The Rutgers alcohol problem index for adolescent alcohol and drug problems: A comprehensive modern psychometric study

Objective: The Rutgers Alcohol Problem Index (RAPI) has been used extensively as a measure of alcohol-related problems experienced by adolescents and young adults. The present study aimed to comprehensively examine the psychometric profile and criterion-related validity of an 18-item RAPI adapted to measure negative consequences resulting from alcohol and other drug use in an at-risk adolescent population. Method: Categorical confirmatory factor analysis and the graded response model were used for evaluations of the latent factor structure, item properties, test information, and item invariance across gender, age groups (middle vs. late adolescence), and drug use profiles (readily available drugs vs. other illicit drugs), as well as computation of the item response theory scale scores for each of 617 alternative high school students (44% female). Results: A reduced set of 16 RAPI items provided plausible evidence of unidimensionality and good measurement precision at a relatively wide range of the latent trait continuum. All but two items were invariant across the drug use profiles. The other illicit drug group had higher levels of the latent substance-related problems than the readily available drug group. Criterion-related validity was supported using a measure of past-year polysubstance use. Conclusions: The RAPI can be effectively modified to measure negative consequences resulting from alcohol and other drug use and reflects a sufficiently wide range of the latent continuum of problem use.