Psychometric properties of the Adjective Rating Scale for Withdrawal across treatment groups, gender, and over time.

The Adjective Rating Scale for Withdrawal (ARSW) is commonly used to assess opiate withdrawal in clinical practice and research. This study aimed to examine the factor structure of the ARSW, test measurement invariance across gender and treatment groups, and assess longitudinal measurement invariance across the clinical trial. Secondary data analysis of National Drug Abuse Treatment Clinical Trials Network protocol CTN-0003, a randomized clinical trial comparing two tapering strategies for buprenorphine/naloxone, was performed. The ARSW was analyzed at baseline, end of taper, and 1-month follow-up (n=515 opioid-dependent individuals). A 1-factor model of the ARSW fit the data and demonstrated acceptable reliability. Measurement invariance was supported across gender and taper groups. Longitudinal measurement invariance was not found across the course of the trial, with baseline assessment contributing to the lack of invariance.

Conclusions: The ARSW appears to be measuring withdrawal equivalently across gender and buprenorphine/naloxone taper periods in opioid-dependent individuals. The authors recommend that researchers and clinicians using this tool analyze ARSW total scores across groups at each time point separately. If changeover time is of interest, change from post-treatment through follow-up may offer the most valid comparison; pre-treatment ARSW values may not be assessing withdrawal in the same way as post-treatment and follow-up values. Future research is needed to replicate these findings in other trials, in various clinical settings, and across other demographic groups in order to fully assess the measurement properties of the ARSW.

Related protocols: CTN-0003