Psychiatric and psychological disorders

AMA5 Chapter 14 is excluded and replaced by this chapter. Before undertaking an impairment assessment, users of the Guidelines must be familiar with (in this order):

  • the Introduction in the Guidelines
  • chapters 1 and 2 of AMA5
  • the appropriate chapter(s) of the Guidelines for the body system they are assessing.

The Guidelines replace the psychiatric and psychological chapter in AMA5.


11.1 This chapter lays out the method for assessing psychiatric impairment. The evaluation of impairment requires a medical examination.

11.2 Evaluation of psychiatric impairment is conducted by a psychiatrist who has undergone appropriate training in this assessment method.

11.3 Permanent impairment assessments for psychiatric and psychological disorders are only required where the primary injury is a psychological one. The psychiatrist needs to confirm that the psychiatric diagnosis is the injured worker’s primary diagnosis.


11.4 The impairment rating must be based upon a psychiatric diagnosis (according to a recognised diagnostic system) and the report must specify the diagnostic criteria upon which the diagnosis is based. Impairment arising from any of the somatoform disorders (DSM IV TR, pp 485–511) are excluded from this chapter.

11.5 If pain is present as the result of an organic impairment, it should be assessed as part of the organic condition under the relevant table. This does not constitute part of the assessment of impairment relating to the psychiatric condition. The impairment ratings in the body organ system chapters in AMA5 make allowance for any accompanying pain.

11.6 It is expected that the psychiatrist will provide a rationale for the rating based on the injured worker’s psychiatric symptoms. The diagnosis is among the factors to be considered in assessing the severity and possible duration of the impairment, but is not the sole criterion to be used. Clinical assessment of the person may include information from the injured worker’s own description of his or her functioning and limitations, and from family members and others who may have knowledge of the person. Medical reports, feedback from treating professionals and the results of standardised tests – including appropriate psychometric testing performed by a qualified clinical psychologist and work evaluations – may provide useful information to assist with the assessment. Evaluation of impairment will need to take into account variations in the level of functioning over time. Percentage impairment refers to whole person impairment (WPI).

Permanent impairment

11.7 A psychiatric disorder is permanent if, in your clinical opinion, it is likely to continue indefinitely. Regard should be given to:

  • the duration of impairment
  • the likelihood of improvement in the injured worker’s condition
  • whether the injured worker has undertaken reasonable rehabilitative treatment
  • any other relevant matters.

Effects of treatment

11.8 Consider the effects of medication, treatment and rehabilitation to date. Is the condition stable? Is treatment likely to change? Are symptoms likely to improve? If the injured worker declines treatment, this should not affect the estimate of permanent impairment. The psychiatrist may make a comment in the report about the likely effect of treatment or the reasons for refusal of treatment.


11.9 Consider comorbid features (eg bi-polar disorder, personality disorder, substance abuse) and determine whether they are directly linked to the work-related injury, or whether they were pre-existing or unrelated conditions.

Pre-existing impairment

11.10 To measure the impairment caused by a work-related injury or incident, the psychiatrist must measure the proportion of WPI due to a pre-existing condition. Pre-existing impairment is calculated using the same method for calculating current impairment level. The assessing psychiatrist uses all available information to rate the injured worker’s pre-injury level of functioning in each of the areas of function. The percentage impairment is calculated using the aggregate score and median class score using the conversion table below. The injured worker’s current level of WPI% is then assessed, and the pre-existing WPI% is subtracted from their current level, to obtain the percentage of permanent impairment directly attributable to the work-related injury. If the percentage of pre-existing impairment cannot be assessed, the deduction is 1/10th of the assessed WPI.

Psychiatric impairment rating scale (PIRS)

11.11 Behavioural consequences of psychiatric disorder are assessed on six scales, each of which evaluates an area of functional impairment:

  1. Self care and personal hygiene (Table 11.1) - Activities of daily living
  2. Social and recreational activities (Table 11.2) - Activities of daily living
  3. Travel (Table 11.3) - Activities of daily living
  4. Social functioning (relationships) (Table 11.4)
  5. Concentration, persistence and pace (Table 11.5)
  6. Employability (Table 11.6).

11.12 Impairment in each area is rated using class descriptors. Classes range from 1 to 5, in accordance with severity. The standard form must be used when scoring the PIRS. The examples of activities are examples only. The assessing psychiatrist should take account of the person’s cultural background. Consider activities that are usual for the person’s age, sex and cultural norms.

Table 11.1: Psychiatric impairment rating scale - self care and personal hygiene

Class 1No deficit, or minor deficit attributable to the normal variation in the general population.
Class 2Mild impairment: Able to live independently; looks after self adequately, although may look unkempt occasionally; sometimes misses a meal or relies on take-away food.
Class 3Moderate impairment: Can't live independently without regular support. Needs prompting to shower daily and wear clean clothes. Does not prepare own meals, frequently misses meals. Family member or community nurse visits (or should visit) 2-3 times per week to ensure minimum level of hygiene and nutrition.
Class 4Severe impairment: Needs supervised residential care. If unsupervised, may accidentally or purposefully hurt self.
Class 5Totally impaired: Needs assistance with basic functions, such as feeding and toileting.

Table 11.2: Psychiatric impairment rating scale - social and recreational activities

Class 1No deficit, or minor deficit attributable to the normal variation in the general population: regularly participates in social activities that are age, sex and culturally appropriate. May belong to clubs or associations and is actively involved with these.
Class 2Mild impairment: Occasionally goes to such events eg without needing a support person, but does not become actively involved (eg dancing, cheering favourite team).
Class 3Moderate impairment: Rarely goes out to such events, and mostly when prompted by family or close friend. Will not go out without a support person. Not actively involved, remains quiet and withdrawn.
Class 4Severe impairment: Never leaves place of residence. Tolerates the company of family member or close friend, but will go to a different room or garden when others come to visit family or flat mate.
Class 5Totally impaired: Cannot tolerate living with anybody, extremely uncomfortable when visited by close family member.

Table 11.3: Psychiatric impairment rating scale - travel

Class 1No deficit, or minor deficit attributable to the normal variation in the general population: Can travel to new environments without supervision.
Class 2Mild impairment: Can travel without support person, but only in a familiar area such as local shops, visiting a neighbour.
Class 3Moderate impairment: Cannot travel away from own residence without support person. Problems may e due to excessive anxiety or cognitive impairment.
Class 4Severe impairment: Finds it extremely uncomfortable to leave own residence even with trusted person.
Class 5Totally impaired: May require two or more persons to supervise when travelling.

Table 11.4: Psychiatric impairment rating scale - social functioning

Class 1No deficit, or minor deficit attributable to the normal variation in the general population: No difficulty in forming and sustaining relationships (eg a partner, close friendships lasting years).
Class 2Mild impairment: Existing relationships strained. Tension and arguments with partner or close family member, loss of some friendships.
Class 3Moderate impairment: Previously established relationships severely strained, evidenced by periods of separation or domestic violence. Spouse, relatives or community services looking after children.
Class 4Severe impairment: Unable to form or sustain long term relationships. Pre-existing relationships ended (eg lost partner, close friends). Unable to care for dependants (eg own children, elderly parent).
Class 5Totally impaired: Unable to function within society. Living away from populated areas, actively avoiding social contact.

Table 11.5: Psychiatric impairment rating scale - concentration, persistence and pace

Class 1No deficit, or minor deficit attributable to the normal variation in the general population. Able to pass a TAFE or university course within normal time frame.
Class 2Mild impairment: Can undertake a basic retraining course, or a standard course at a slower pace. Can focus on intellectually demanding tasks for periods of up to 30 minutes, then feels fatigued or develops headache.
Class 3Moderate impairment: Unable to read more than newspaper articles. Finds it difficult to follow complex instructions (eg operating manuals, building plans), make significant repairs to motor vehicle, type long documents, follow a pattern for making clothes, tapestry or knitting.
Class 4Severe impairment: Can only read a few lines before losing concentration. Difficulties following simple instructions. Concentration deficits obvious even during brief concentration. Unable to live alone, or needs regular assistance from relatives or community services.
Class 5Totally impaired: Needs constant supervision and assistance within institutional setting.

Table 11.6: Psychiatric impairment rating scale - employability

Class 1No deficit, or minor deficit attributable to the normal variation in the general population. Able to work full time. Duties and performance are consistent with the injured worker's education and training. The person is able to cope with the normal demands of the job.
Class 2Mild impairment: Able to work full time but in a different environment from that of the pre-injury job. The duties require comparable skill and intellect as those of the pre-injury job. Can work in the same position, but no more than 20 hours per week (eg no longer happy to work with specific persons, or work in a specific location due to travel required).
Class 3Moderate impairment: Cannot work at all in same position. Can perform less than 20 hours per week in a different position, which requires less skill or is qualitatively different (eg less stressful).
Class 4Severe impairment: Cannot work more than one or two days at a time, less than 20 hours per fortnight. Pace is reduced, attendance is erratic.
Class 5Totally impaired: Cannot work at all.

Using the PIRS to measure impairment

11.13 Rating psychiatric impairment using the PIRS is a two-step procedure:

  1. Determine the median class score.
  2. Calculate the aggregate score.

Determining the median class score

11.14 Each area of function described in the PIRS is given an impairment rating which ranges from Class 1 to 5. The six scores are arranged in ascending order, using the standard form. The median is then calculated by averaging the two middle scores eg:

  • Example A: 1, 2, 3, 3, 4, 5 Median Class = 3
  • Example B: 1, 2, 2, 3, 3, 4 Median Class = 2.5 = 3*
  • Example C: 1, 2, 3, 5, 5, 5 Median Class = 4

*If a score falls between two classes, it is rounded up to the next class. A median class score of 2.5 thus becomes 3.

11.15 The median class score method was chosen as it is not influenced by extremes. Each area of function is assessed separately. While impairment in one area is neither equivalent nor interchangeable with impairment in other areas, the median seems the fairest way to translate different impairments onto a linear scale.

Median class score and percentage impairment

11.16 Each median class score represents a range of impairment, as shown below:

  • Class 1 = 0–3%
  • Class 2 = 4–10%
  • Class 3 = 11–30%
  • Class 4 = 31–60%
  • Class 5 = 61–100%

Calculation of the aggregate score

11.17  The aggregate score is used to determine an exact percentage of impairment within a particular median class range. The six class scores are added to give the aggregate score. Use of the conversion table to arrive at percentage impairment

11.18 The aggregate score is converted to a percentage score using the conversion Table 11.7, below.

11.19 The conversion table was developed to calculate the percentage impairment based on the aggregate and median scores.

11.20 The scores within the conversion table are spread in such a way to ensure that the final percentage rating is consistent with the measurement of permanent impairment percentages for other body systems.

Table 11.7 Conversion table

Conversion table — explanatory notes

a. Distribution of aggregate scores

  • The lowest aggregate score that can be obtained is: 1+1+1+1+1+1=6.
  • The highest aggregate score is 5+5+5+5+5+5= 30.
  • The table therefore has aggregate scores ranging from six to 30.
  • Each median class score has an impairment range, and a range of possible aggregate scores (eg class 3 = 11-30 per cent).
  • The lowest aggregate score for class 3 is 13 (1 + 1 + 2 + 3 + 3 + 3 = 13).
  • The highest aggregate score for class 3 is 22 (3 + 3 + 3 + 3 + 5 + 5 = 22).
  • The conversion table distributes the impairment percentages across aggregate scores.

b. Same aggregate score in different classes

  • The conversion table shows that the same aggregate score leads to different percentages of impairment in different median classes.
  • For example, an aggregate score of 18 is equivalent to an impairment rating of
    • 10% in Class 2,
    • 22% in Class 3,
    • 34% in Class 4.
  • This is due to the fact that an injured worker whose impairment is in median class 2 is likely to have a lower score across most areas of function. They may be significantly impaired in one aspect of their life, such as travel, yet have low impairment in social function, self-care or concentration.
  • Someone whose impairment reaches median class 4 will experience significant impairment across most aspects of his or her life.

Table 11.8: PIRS rating form

Part A of PIRS rating form - claimant information

Part B of the PIRS rating form - diagnosis details

Part C of the PIRS rating form - PIRS class and reason for decision

Score class and aggregate score model