ICD-11 Criteria for Disorders of Intellectual Development (6A00)

Disorders of intellectual development are a group of etiologically diverse conditions originating during the developmental period characterised by significantly below average intellectual functioning and adaptive behaviour that are approximately two or more standard deviations below the mean (approximately less than the 2.3rd percentile), based on appropriately normed, individually administered standardized tests. Where appropriately normed and standardized tests are not available, diagnosis of disorders of intellectual development requires greater reliance on clinical judgment based on appropriate assessment of comparable behavioural indicators.

Coding Note:     Use additional code, if desired, to identify any known aetiology.

Exclusions:             

• Dementia (BlockL2‑6D8)

6A00.0     Disorder of intellectual development, mild

A mild disorder of intellectual development is a condition originating during the developmental period characterised by significantly below average intellectual functioning and adaptive behaviour that are approximately two to three standard deviations below the mean (approximately 0.1 – 2.3 percentile), based on appropriately normed, individually administered standardized tests or by comparable behavioural indicators when standardized testing is unavailable. Affected persons often exhibit difficulties in the acquisition and comprehension of complex language concepts and academic skills. Most master basic self-care, domestic, and practical activities. Persons affected by a mild disorder of intellectual development can generally achieve relatively independent living and employment as adults but may require appropriate support

6A00.1      Disorder of intellectual development, moderate

A moderate disorder of intellectual development is a condition originating during the developmental period characterised by significantly below average intellectual functioning and adaptive behaviour that are approximately three to four standard deviations below the mean (approximately 0.003 – 0.1 percentile), based on appropriately normed, individually administered standardized tests or by comparable behavioural indicators when standardized testing is unavailable. Language and capacity for acquisition of academic skills of persons affected by a moderate disorder of intellectual development vary but are generally limited to basic skills. Some may master basic self-care, domestic, and practical activities. Most affected persons require considerable and consistent support in order to achieve independent living and employment as adults.

6A00.2      Disorder of intellectual development, severe

A severe disorder of intellectual development is a condition originating during the developmental period characterised by significantly below average intellectual functioning and adaptive behaviour that are approximately four of more standard deviations below the mean (less than approximately the 0.003rd percentile), based on appropriately normed, individually administered standardized tests or by comparable behavioural indicators when standardized testing is unavailable. Affected persons exhibit very limited language and capacity for acquisition of academic skills. They may also have motor impairments and typically require daily support in a supervised environment for adequate care, but may acquire basic self-care skills with intensive training. Severe and profound disorders of intellectual development are differentiated exclusively on the basis of adaptive behaviour differences because existing standardized tests of intelligence cannot reliably or validly distinguish among individuals with intellectual functioning below the 0.003rd percentile.

6A00.3      Disorder of intellectual development, profound

A profound disorder of intellectual development is a condition originating during the developmental period characterised by significantly below average intellectual functioning and adaptive behaviour that are approximately four of more standard deviations below the mean (approximately less than the 0.003rd percentile), based on individually administered appropriately normed, standardized tests or by comparable behavioural indicators when standardized testing is unavailable. Affected persons possess very limited communication abilities and capacity for acquisition of academic skills is restricted to basic concrete skills. They may also have co-occurring motor and sensory impairments and typically require daily support in a supervised environment for adequate care. Severe and profound disorders of intellectual development are differentiated exclusively on the basis of adaptive behaviour differences because existing standardized tests of intelligence cannot reliably or validly distinguish among individuals with intellectual functioning below the 0.003rd percentile.

6A00.4       Disorder of intellectual development, provisional

Disorder of intellectual development, provisional is assigned when there is evidence of a disorder of intellectual development but the individual is an infant or child under the age of four or it is not possible to conduct a valid assessment of intellectual functioning and adaptive behaviour because of sensory or physical impairments (e.g., blindness, pre-lingual deafness), motor or communication impairments, severe problem behaviours or co-occurring mental and behavioural disorders.

6A00.Z       Disorders of intellectual development, unspecified

Coding Note:     Use additional code, if desired, to identify any known aetiology.

REFERENCE:

International Classification of Diseases Eleventh Revision (ICD-11). Geneva: World Health Organization; 2022. License: CC BY-ND 3.0 IGO.

https://creativecommons.org/licenses/by-nc-nd/3.0/igo/