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ICD and stammering

What is the ICD?

The ICD is the World Health Organisation's International Statistical Classification of Diseases and related health problems. The current revision, the tenth, is known as ICD-10. ICD-10 Homepage - WHO website.

Why is it relevant to the DDA?

Schedule 1 para 1 of the DDA said before 5th December 2005 that a mental impairment includes an impairment resulting from or consisting of a mental illness only if the illness is a clinically well-recognised illness. (The Disability Discrimination Act 2005 abolished this requirement from 5th December 2005.) The official guidance on the definition of disability at para 14 says it is very likely that this would include those specifically mentioned in publications such as the World Health Organisation's International Classification of Diseases.

Even before December 2005, para 1 was not relevant if stammering is a 'physical' impairment, which it may well be under the Blacker case. Even if it is a 'mental' impairment, I do not think stammering is a mental "illness" (see Dunham v Ashford Windows, contradicting the earlier Morgan v Staffordshire University case). However, I deal below with stammering under the ICD in case that is wrong. Note that in any event the ICD is not conclusive. Even if stammering does have to pass the para 1 test, what matters is whether it is clinically well-recognised (see further Morgan v Staffordshire University), and my understanding is that it is.

What does ICD-10 say about stammering?

Stammering is covered by ICD-10 at F98.5:

F98.5 Stuttering [stammering]
Speech that is characterised by frequent repetition or prolongation of sounds or syllables or words, or by frequent hesitations or pauses that disrupt the rhythmic flow of speech. It should be classified as a disorder only if its severity is such as to markedly disturb the fluency of speech.

There are certain exclusions, such as cluttering which falls within F98.6.

The relevant ICD-10 text can be found at www.who.int/classifications/apps/icd/icd10online/

Some stammers excluded by the ICD-10 wording?

Very minor stammer?

The second sentence of F98.5 appears to exclude a stammer which does not "markedly disturb the fluency of speech". In my Collins dictionary, 'marked' means 'obvious evident or noticeable' which seems to be a very low threshhold.

The general view is that a minor stammer is excluded from the DDA anyway. I think it would be difficult to exclude a stammer on the ICD wording where the DDA test is met. The ICD wording might be argued to restrict the meaning of 'impairment' in eg deduced effects cases, but that would be a very odd interpretation of the DDA.

In any event I doubt that the ICD wording could be used to exclude certain minor stammers from being a 'mental impairment' under the DDA. It can be argued that the severity of the stammer, while perhaps relevant for statistical purposes of the ICD, is not relevant to whether stammering is clinically well recognised and meets the DDA Schedule 1 para 1 test. The EAT commented in the Blackedge case below that a particular criterion (albeit in a classification other than ICD-10) seemed to it to be more relevant to deciding the effect on function which a mental impairment has rather than deciding whether a mental impairment exists under section 1 DDA. The same seems to apply to a criterion based on the severity of a stammer.

Covert stammer

The F98.5 wording could also exclude a covert stammer. However, as I say above, the ICD is not conclusive. Even if stammering does have to be judged against the DDA Schedule 1 para 1 test, I would expect expert evidence to be available that covert stammering is clinically well-recognised, or is an aspect of the clinically well-recognised condition of stammering.

ICD-NA

IDC-NA is the Application of the International Classification of Diseases to Neurology. About ICD-NA - WHO Mental Health Bulletin website.

ICD-NA adds a gloss on ICD-10 by giving a distinct classification to stammering "of organic origin", namely R47.80. It distinguishes this from "psychogenic" stammering under F98.5. My understanding is that normal developmental stammering would fall within F98.5 and not R47.80.

ICF

It may not be relevant but the new International Classification of Functioning, Disability and Health (ICF) adopted by the World Health Organisation in 2001 also includes stuttering/stammering (b3300). The ICF is available online. ICF Homepage - WHO website.

The ICF is a revision of the former ICIDH - International Classification of Impairments, Disabilities and Handicaps.

Blackedge case and DSM-IV

In Blackedge v London General Transport Services, EAT 1073/00, the Tribunal considered a case of alleged post-traumatic stress disorder. The employment tribunal considered both ICD-10 and the American classification DSM-IV. One difference in the classifications was that under DSM-IV (but not ICD-10) the disorder should be diagnosed only if the disturbance causes clinically significant distress or impairment in social, occupational or other important areas of functioning.

The EAT held that the employment tribunal should not have used that criterion to find that the applicant's condition was not well recognised. It should have used ICD-10: "The Guidance suggests that the definition in ICD-10 represents a respected body of medical opinion and as the evidence before the Tribunal was that ICD-10 is the classification recognised by the NHS, it is difficult to see how that classification was not used by the Tribunal in determining whether there was a mental impairment. The additional requirement in DSM-IV of clinically significant distress or impairment in functioning seems to us to be more relevant to deciding the effect on function which a mental impairment has rather than deciding whether a mental impairment exists under section 1 of the Disability Discrimination Act."


Definition of Disability: Physical or mental impairment

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© Allan Tyrer 1999-2005
Last updated 17th July, 2003 (minor updates to 10 December 2005)