Concordance between the diagnostic guidelines for alcohol and cannabis use disorders in the draft ICD-11 and other classification systems: analysis of data from the WHO's World Mental Health Surveys

Abstract

Background and aims: The World Health Organization’s proposed International Classification of Diseases, 11th Edition (ICD-11) includes several major revisions to substance use disorder (SUD) diagnoses. It is essential to ensure the consistency of within-subject diagnostic findings across countries, languages and cultures. To date, agreement analyses between different SUD diagnostic systems have largely been based in high-income countries and clinical samples rather than general population samples.

Design: Face-to-face household surveys.

Setting: Representative surveys of the general population in ten countries (Argentina, Australia, Brazil, Colombia, Iraq, Northern Ireland, Poland, Portugal, Romania and Spain) of the World Mental Health Survey Initiative.

Participants: Questions about SUDs were asked of 12,182 regular alcohol users and 1,788 cannabis users.

Measurements: Analyses examined prevalence of, and concordance between, ICD-11, ICD-10, DSM-5 and DSM-IV diagnoses; prevalence of disaggregated ICD-10 and ICD-11 symptoms; and variation in clinical features across diagnostic groups.

Findings: Among regular alcohol users, prevalence (95% confidence interval) of lifetime ICD-11 alcohol harmful use and dependence were 21.6% (20.5%−22.6%) and 7.0% (6.4%−7.7%), respectively. Among cannabis users, 9.3% (7.4%−11.1%) met criteria for ICD-11 harmful use and 3.2% (2.3%−4.0%) for dependence. For both substances, all comparisons of ICD-11 with ICD-10 and DSM-IV showed excellent concordance (all κ≥0.90). Concordance between ICD-11 and DSM-5 ranged from good (for SUD, and comparisons of dependence and severe SUD) to poor (for comparisons of harmful use and mild SUD). Very low endorsement rates were observed for new ICD-11 feature for harmful use (‘harm to others’). Minimal variation in clinical features was observed across diagnostic systems.

Conclusions: Though modifications were made to ICD-11, classifications are extremely consistent with ICD-10 and DSM-IV. Concordance between ICD-11 and DSM-5 varies, largely due to low levels of agreement for the ICD harmful use and DSM-5 mild use disorder. Diagnostic validity of self-reported “harm to others” is questionable