Elsevier

Addictive Behaviors

Volume 37, Issue 6, June 2012, Pages 709-715
Addictive Behaviors

Psychometric properties of the CAST and SDS scales in young adult cannabis users

https://doi.org/10.1016/j.addbeh.2012.02.012Get rights and content

Abstract

Aim

To assess the validity of two cannabis use severity scales among young cannabis users and to evaluate their ability to detect Substance Use Disorders (SUD).

Participants

241 volunteers (18–25 years), with a wide spectrum of cannabis use in the last 12 months.

Measurements

The Cannabis Abuse Screening Test (CAST) and Severity of Dependence Scale (SDS) were self-administered. The Psychiatric Interview for Substance and Mental Disorders (PRISM) was used as gold standard for cannabis use disorders according to DSM-IV. Reliability and validity were assessed for two different CAST coding algorithms (b—binary and f—full) and for the SDS. In addition, the cannabis use diagnostic criteria contained in the PRISM were grouped to approximate forthcoming proposed DSM-V criteria to further evaluate these scales.

Findings

26.6% (95% CI: 21.0–32.2) of the subjects met criteria for cannabis dependence, and 49.0% (95% CI: 42.7–55.3) for cannabis use disorders. For both scales internal consistency (Cronbach's alpha > 0.71) and test–retest intraclass correlation coefficients (> 0.80) were good. The score 12 in the CAST-full discriminated better than others between presence and absence of dependence (27.0%; 95% CI: 21.4–32.6) while the score for discrimination of SUD was 9 (51.5%; 95% CI: 45.1–57.8). For the SDS the values were 7 (22.0%; 95% CI: 16.8–27.2) and 3 (64.7%; 95% CI: 58.7–70.8), respectively. According to proposed DSM-V criteria, for moderate and severe addiction the values for the CAST-f were 7 (68.5%; 95% CI: 62.5–74.3) and 12 (27%; 95% CI: 21.3–32.6) and for the SDS, 3 (65.0%; 95% CI: 58.7–70.8) and 7 (22%; 95% CI: 17.0–34.3), respectively.

Conclusions

The CAST and SDS applied to young cannabis users are reliable and valid measures to detect cannabis use disorders when compared to both DSM-IV and proposed DSM-V criteria.

Highlights

► The CAST and SDS are reliable and valid measures to detect cannabis use disorders. ► We found a more complex internal structure than previously described for both scales. ► CAST full scoring version has better known-groups criterion validity.

Introduction

Cannabis was the most extensively used illegal drug worldwide in 2009 (United Nations Office on Drugs and Crime, 2011). In 2010, the prevalence of having consumed cannabis in the last year in the European population aged between 15 and 34 years was 12.6% (European Monitoring Centre for Drugs, Drug Addiction (EMCDDA) (EMCDDA), 2010); Spain with a prevalence of 18.8%, being one of the leading countries (Observatorio Español de Drogas, 2009). Regular cannabis consumption has been associated with the presence of various types of problems: cognitive (Solowij, Stephens, & Roffman, 2002), psychiatric (Drewe et al., 2004, Gutiérrez-Rojas et al., 2006) and social (Lynskey & Hall, 2000). At psychopathological level, associations are often found between cannabis consumption and mood disorders, anxiety disorders (Lynskey, Glowinski, & Todorov, 2004) and psychotic disorders (Henquet et al., 2005, Stefanis et al., 2004). Despite all these problems, various studies and indicators of treatment show that the proportion of subjects seeking treatment specifically for cannabis use disorder is low (National Survey on Drug Use and Health. Substance Abuse and Mental Health Services Administration, Office of Applied Studies, 2008, Stinson et al., 2006).

Given the increased cannabis consumption and to permit better planning of public health interventions, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) has promoted the use of scales for measuring problematic cannabis use in population surveys. Moreover, making easily administered scales capable of early detection of abusive and problematic use of cannabis available in primary health services could help to detect such conditions among patients admitted for other reasons; and this is crucial to avoid the consequences deriving from such consumption (European Monitoring Centre for Drugs, Drug Addiction (EMCDDA) (EMCDDA), 2010).

Both the Cannabis Abuse Screening Test (CAST) (Legleye, Karila, Beck, & Reynaud, 2007) and the Severity of Dependence Scale (SDS) (Gossop et al., 1995) are among the questionnaires used in European population surveys. The former, designed recently in France, is specific to cannabis, targets adolescents and young people, and aims to detect problematic cannabis use (Chassevent-Pajot et al., 2011, Legleye et al., 2010). The SDS assesses psychological aspects of substance dependence, related with feelings of control, worry and anxiety about drug consumption, and has been used extensively in various countries for many substances, including cannabis (Ferri et al., 2000, Gonzalez-Saiz et al., 2008, Gonzalez-Saiz et al., 2009, Kedzior et al., 2006, Martin et al., 2006, Steiner et al., 2008). These two scales were adapted to Spanish and incorporated into the Spanish school survey ESTUDES-06 (Observatorio Español de Drogas, 2007) to evaluate cannabis consumption among these young people, aged 14 to 18 years of age. However, the scales would need to be further validated to enable determination of cut-off scores for disorders due to cannabis use.

Furthermore, the forthcoming version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) (American Psychiatric Association, 2011) does not distinguish categorically between substance abuse and dependence. It is proposed instead to have a single diagnosis with graduated severity: “Addiction and related disorders”, which groups together all dependence criteria and all, except legal, abuse criteria. In the case of cannabis, withdrawal criteria will be added, something not considered for this substance in version IV. To receive this diagnosis, an individual will need to meet at least 2 criteria (2–3 criteria: moderate addiction; 4 or more: severe addiction).

Therefore, the purpose of this paper is to study the validity of CAST and SDS for assessing the severity of cannabis use among young users, and to evaluate their ability to detect SUD taking into account DSM-IV (American Psychiatric Association, 1994) and proposed DSM-V criteria.

Section snippets

Subjects

The present paper reports on a cross-sectional study of regular cannabis users fulfilling the following inclusion criteria: either sex, aged 18 to 25 years, had consumed cannabis regularly (at least 12 times) in the last 12 months, and were residents of Barcelona or environs; and as exclusion criteria they should not have met criteria for current abuse or dependence for any other illegal substance. Recruitment took place between July 2007 and March 2010 by distributing leaflets, directing to a

Results

A total of 241 subjects, 65% men, were studied. Their average age was 21.0 (SD 2) years. The average age of onset of cannabis use was 15.0 (SD 1.6) years, that of alcohol use was 14.4 years in men and 14.1 in women. Half the subjects (51%) consumed cannabis daily, 30% weekly, and 19% monthly. Overall, 33% consumed between 3 and 4 joints per day of use, on average 73.4 per month (SD 83.1). The majority had been consuming for between 5 and 7 years (Table 1).

Discussion

Good reliability scores, for both internal consistency and test–retest analysis, were obtained for both the CAST and SDS. The scales present adequate concurrent validity: subjects with more intense use being the ones who obtain the highest scores. In relation to construct validity we highlighted two dimensions for the CAST and two for the SDS, the latter with a more complex pattern. The scales also present adequate ability to distinguish between known-groups, since the prevalences yielded by

Role of funding sources

Funding for this study was provided by different national agencies stated in the Acknowledgements section. These institutions had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the paper for publication.

Contributors

Antònia Domingo-Salvany, Albert Sánchez-Niubó and Josep M Suelves designed the study and wrote the protocol. Aida M Cuenca-Royo, Marta Torrens and Antònia Domingo-Salvany conducted literature searches and provided summaries of previous research studies. Aida M Cuenca-Royo, Albert Sánchez-Niubó and Carlos G Forero conducted the statistical analysis. Aida M Cuenca-Royo wrote the first draft of the manuscript and all authors contributed to and have approved the final manuscript.

Conflict of interest

None of the authors has conflict of interest.

Acknowledgements

We are grateful for the support provided by grants from the Instituto de Salud Carlos III FEDER (PI070960), ETS (PI06/90491), FIS-Redes de investigación cooperativa RD06/0001/1009 and RD06/0001/1018; and AGAUR 2009 SGR 00718. Albert Sánchez-Niubó is supported by ISCIII grant CA08/00214. Carlos García Forero is supported by a “Ministerio de Ciencia e Innovación” FSE grant (JCI-2009-05486). We also are grateful to Joan Rodriguez for recruitment and to Dave Macfarlane for English revision.

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