Assessing the validity of the Wechsler Adult Intelligence Scale (WAIS-IV) in predicting completion in a long-term residential rehabilitation for substance use problems.

BACKGROUND We aimed to examine the predictive validity of the Weschler Adult Intelligence Scale (WAIS-IV) in predicting treatment completion, over and above educational status. METHODS One hundred and ninety-six (N = 196) individuals from the Odyssey House Residential Rehabilitation Program, NSW, Australia between 2010 and 2016 were administered a structured interview including substance use disorders and the Verbal Comprehension (VCI), Perceptual Reasoning (PRI), Working Memory (WMI), and Processing Speed (PSI) domains of the WAIS-IV. RESULTS There were significant differences between our clinical sample and the population norm with respect to the proportion below the mean for PSI (z = 12.27, p  .16) over and above educational status (p < .01). CONCLUSIONS Our findings suggest that in clients in drug and alcohol rehabilitation settings a combination of skills may be impacted including Verbal Comprehension and Processing Speed. Moreover, our findings also suggest that WAIS-IV subscales do not predict treatment completion in a drug and alcohol residential setting, over and above a brief assessment of educational status.