Background and objectives: Specific classifications of mental health interventions have encountered many issues in their integration into a general classification of interventions. Nonetheless, there has not been any previous review on the content and structure of current classifications in relation to mental health care. This expert review aimed to compare the mental health interventions provided in a series of reference classification systems for the incorporation of mental health care into the International Classification of Health Interventions (ICHI).

Methods: Twelve classifications are described with regards to the structure of the classification (unit of analysis, sections, multiaxiality, granularity) and context of utilization (purpose, descriptors, neutrality, interoperability and implementation).

Results: Major problems identified include a granularity unbalance (i.e. differences in the number of codes and its specificity with other areas such as rehabilitation), unclear units of analysis (i.e. differences between procedures, interventions, packages of care and care programs), lack of clearly stated evidence-based interventions in a mental health context; and lack of a well-defined taxonomical tree. An ontology approach to the definition of the different entities involved in the throughput of mental care, including their hierarchical relationships and conceptual map, may have contributed to the failure of previous systems together with the development of systems to classify mental health interventions separate from generic health interventions.

Conclusions: The present review provides additional ground for the development of the ICHI knowledge-base and highlights the importance of taxonomical disambiguation and international comparability in the development and implementation of classifications of mental care interventions.