ICF

The International Classification of Functioning, Disability and Health (ICF) of the World Health Organization (WHO) focuses on functional status and disability, which, although relevant, provides only a limited perspective on the psychopathological aspects assessed by psychiatric instruments.

The ICF comprises around 1,424 codes, which are organized into different domains. These codes are divided into four main components:

Component	Description
Body functions (b)	e.g. mental functions, sensory functions and pain
Activities and participation (d)	e.g. structures of the nervous system, structures of the musculoskeletal system
Body structures (s)	e.g. learning, communication, mobility, social interaction
Environmental factors (e)	e.g. products and technologies, support from other people, environmental conditions

Because the ICF terminology is less granular than other terminologies, it is used first and foremost for the classification of functionality - the limitation of which is asked about in the questionnaire. While the ICF terminology is well suited for filtering processes of items, SNOMED CT is a fine-granular method to capture more detailed information, symptoms and also answer options.