Alcohol and Cannabis Simultaneous Use Scale (ACSUS)

Abstract

The Alcohol and Cannabis Simultaneous Use Scale (ACSUS), developed by Kolp et al. in 2024, is a 9-item self-report inventory designed to quantify patterns and associated problems related to Simultaneous Alcohol and Cannabis Use (SAM). The scale was constructed based on prior research into SAM behavior and incorporates modified components adapted from established instruments such as the Alcohol Use Disorders Identification Test (AUDIT) and the Cannabis Use Disorders Identification Test-Revised (CUDIT-R). Initial psychometric evaluation, conducted on a sample of U.S. college students who engage in both substance uses, confirmed a robust two-factor structure. This structure comprises four items measuring SAM use frequency and quantity, and five items assessing related problems, demonstrating acceptable reliability and validity for use in clinical and research settings.

Keywords

Alcohol Use, Cannabis Use, Simultaneous Drug Use, Use Frequency, Use Quantity, Associated Problems with Use, Drug Interactions, Marijuana, Substance Use and Addiction Measures, College Students.

Authors

Kolp, Haley, Horvath, Sarah, Fite, Paula J., Metrik, Jane, Stuart, Gregory L., Lisdahl, Krista M., Shorey, Ryan C.

Purpose

The primary purpose of the ACSUS is to provide a standardized, brief measure of the specific risks associated with the simultaneous consumption of alcohol and cannabis. Traditional substance use measures often assess alcohol and cannabis consumption separately, failing to capture the unique pharmacological effects and increased risks inherent in their combined, overlapping use (SAM). The scale addresses this critical measurement gap by targeting three key domains of SAM behavior: frequency of simultaneous use, typical quantity consumed during these occasions, and the related negative consequences or problems experienced by the user.

The resulting total score ranges from 0 to 36, where higher scores are indicative of greater involvement in simultaneous alcohol and cannabis use and more severe associated problems. The scale is intended for screening and research purposes among populations known to engage in polydrug use, particularly young adults.

Construct

The ACSUS measures the construct of Alcohol and Cannabis Simultaneous Use. This construct specifically focuses on instances where the psychoactive effects of both substances overlap temporally, distinguishing it from general concurrent use (using both substances at different, non-overlapping times on the same day). The scale operationalizes this construct through two distinct, empirically verified dimensions, allowing for nuanced assessment of the behavior:

• Factor 1: SAM use frequency and quantity (Items 1–4).
• Factor 2: Problems associated with SAM use (Items 5–9).

Validity

The validity of the ACSUS was established through comprehensive psychometric evaluation. A key finding was the demonstration of Concurrent Validity. The ACSUS total score showed significant correlations with established, validated measures of substance use severity, confirming its relevance to existing diagnostic frameworks.

Specifically, strong correlations were observed with the Alcohol Use Disorders Identification Test (AUDIT) and the Cannabis Use Disorders Identification Test-Revised (CUDIT-R). Furthermore, the scale demonstrated significant relationships with measures of related psychological constructs, including impulsivity (as measured by the SUPPS-P) and specific motives driving SAM use, reinforcing its ability to accurately capture the intended clinical and behavioral constructs associated with combined substance misuse.

Reliability

Internal consistency reliability for the ACSUS was assessed using Cronbach’s alpha (α) across the total scale and its two derived factors. The overall ACSUS demonstrated acceptable reliability with an internal consistency of α = 0.70. Reliability estimates for the individual factors were also reported and were close to the widely accepted threshold for new measures:

• Factor 1 (SAM use frequency and quantity): α = 0.68.
• Factor 2 (Problems associated with SAM use): α = 0.69.

These values indicate that the items within the scale and its subscales consistently measure their respective underlying components of simultaneous substance use behavior, providing a reliable basis for research and clinical applications.

Factor Analysis

The underlying structure and dimensionality of the 9-item ACSUS were rigorously examined using both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) during its development. The EFA confirmed the presence of a two-factor solution, which was reached after one initial item was removed due to problematic cross-loading onto both factors.

The final 9-item, 2-factor model was then subjected to CFA to confirm the structure in a separate sample. The fit indices demonstrated a good fit to the data, supporting the empirical distinction between the two subscales:

• Chi-square: χ²(26) = 45.75, p < .05
• Comparative Fit Index (CFI): .99
• Root Mean Square Error of Approximation (RMSEA): .05
• Standardized Root Mean Square Residual (SRMR): .09

Instrument

Test Type: Inventory/Questionnaire

Format: Multiple-choice, utilizing 3 to 5 response options per item. Item 3, which assesses typical cannabis quantity, includes a visual aid adapted from the Daily Sessions, Frequency, Age of Onset, and Quantity of Cannabis Use Inventory (DFAQ-CU) to assist respondents in accurately estimating cannabis quantity in grams.

Language Available: English (Original development language)

Population Group: Human; Male; Female; Transgender

Age Group: Adulthood (18+ years); Young Adulthood (18-29 years)

Population Details: The scale was validated on a specific population of college students in the United States who reported using both alcohol and cannabis. Reported gender identities included Male, Female, Transgender, Genderqueer, and Gender Nonconforming.

Test Methodology: Test Reliability; Internal Consistency; Factor Analysis; Confirmatory Factor Analysis; Exploratory Factor Analysis.

Keywords

Alcohol Use Disorders Identification Test, Cannabis Use Disorders Identification Test-Revised, Impulsivity, College Students, Psychometrics, Substance Use Screening, Polydrug Use.

Authors

Author ORCID Identifier: Horvath, Sarah: 0000-0001-7884-958X

Affiliation Email addresses: The corresponding author’s email is [email protected].

Correspondence Address: Kolp, Haley: University of Wisconsin-Milwaukee, Department of Psychology, 2441 E Hartford Ave, Milwaukee, WI, United States, 53211.

Affiliations:

• Kolp, Haley – University of Wisconsin-Milwaukee, Department of Psychology
• Horvath, Sarah – Ohio University, Department of Psychology
• Fite, Paula J. – University of Kansas, Department of Applied Behavioral Science
• Metrik, Jane – Brown University School of Public Health, Center for Alcohol and Addiction Studies
• Stuart, Gregory L. – University of Tennessee-Knoxville, Department of Psychology
• Lisdahl, Krista M. – University of Wisconsin-Milwaukee, Department of Psychology
• Shorey, Ryan C. – University of Wisconsin-Milwaukee, Department of Psychology

Permissions & Fee and Test Year

The scale was developed and published in 2024. Information regarding specific usage fees or detailed permissions beyond standard academic citation is not explicitly provided in the source material. Users seeking to implement the ACSUS in non-research contexts or requiring formal permissions should contact the corresponding author, Haley Kolp, via the provided correspondence address or email.

Reference’s

Kolp, H., Horvath, S., Fite, P. J., Metrik, J., Stuart, G. L., Lisdahl, K. M., & Shorey, R. C. (2024). Development of the Alcohol and Cannabis Simultaneous Use Scale (ACSUS) in college students. Journal of Substance Use, 29(4), 509–516. DOI: 10.1080/14659891.2023.2183149.

Items of the Alcohol and Cannabis Simultaneous Use Scale (ACSUS)

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

Instructions: The following questions ask about your use of alcohol and marijuana at approximately the same time, so that the effects of each substance overlapped. That is, these questions ask about times you have used alcohol and marijuana together.

Response options for items 1 through 7 are coded from 0 to 4. For items 8 and 9, responses are coded as 0 (Never), 2 (Yes, but not in the past 12 months), and 4 (Yes, in the past 12 months). Total ACSUS scores can be calculated by summing all 9 items, yielding a range of 0 to 36. Subscale scores can also be calculated separately by summing items 1-4 (quantity/frequency) or items 5-9 (associated problems).