Medical assessor guidance note 19

Mental and Behavioural Disorders Impairment:

Determination of a recognised psychiatric diagnosis

This material is issued by the Motor Accidents Authority under s65(2) of the Motor Accidents Compensation Act 1999 (the Act) in the interests of promoting accurate and consistent medical assessments under the Act. The interpretation provided here is not legally binding but represents the clinically recommended interpretation in an area where more than one interpretation of existing provisions may be possible. This recommended interpretation is publically available. Any medical assessment which does not adopt this interpretation should be accompanied by clinical justification for the interpretation adopted, supported by full, robust reasons.


The Motor Accidents Authority Permanent Impairment Guidelines – Guidelines for the assessment of permanent impairment of a person injured as a result of a motor vehicle accident 1 October 2007 (MAA Guidelines): Chapter 7 Mental and Behavioural Disorders Impairment pages 38 – 47 and clause 7.13 page 39.


Clause 7.13 of the MAA Guidelines directs that:

"The impairment must be attributable to a recognised psychiatric diagnosis in accordance with the Diagnostic Statistics Manual of Mental Disorders (4th Edition) [DSM IV], Internal Classification of Diseases (10th Edition) [ICD 10] or a substantial body of peer review research literature.1 The impairment evaluation report must specify the diagnostic criteria upon which the diagnosis is based."

At the time of publication of the MAA Guidelines the DSM IV and ICD 10 were the current manuals or texts generally used to make a psychiatric diagnosis and accordingly were specifically referenced in clause 7.13 of the MAA Guidelines. In May 2013 the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM 5) was released and in 2015 the Eleventh Edition of the International Classification of Diseases (ICD) is due to be released.

Issues requiring clarification

With the publication of the DSM 5 it may be unclear for Psychiatric Medical Assessors whether it is open to them, under the current MAA Guidelines, to make a psychiatric diagnosis in accordance with DSM 5.

Preferred approach

The DSM 5 may be considered by Psychiatric Medical Assessors as "a substantial body of peer review research literature." (clause 7.13 MAA Guidelines)

Any diagnosis based on DSM 5 must be clearly referenced and "must specify the diagnostic criteria upon which the diagnosis is based". (clause 7.13 MAA Guidelines)

However, Psychiatric Medical Assessors are reminded that somatoform disorders, which are categorised as Somatic Symptom and Related Disorders under DSM 5 are not assessed under the MAA Guidelines (clause 7.15 MAA Guidelines).

Justification for preferred interpretation

The preferred interpretation is suggested to promote consistency of assessment and to assist the parties to understand the methodology behind the diagnosis of psychiatric injuries and associated impairment.


1. The MAA Permanent Impairment Guidelines incorrectly states the titles of DSM IV and ICD 10. The correct titles are as follows: Diagnostic and Statistical Manual of Mental Disorders (4th Edition) and International Classification of Diseases (10th Edition).

Issued by:

Injury Strategy Branch

September 2014