AMA5 Chapter 5 (p 87) applies to the assessment of permanent impairment of the respiratory system, subject to the modifications set out below. Before undertaking an impairment assessment, users of the Guidelines must be familiar with:
- 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 appropriate chapter(s) of AMA5 for the body system they are assessing.
The Guidelines take precedence over AMA5.
8.1 AMA5 Chapter 5 provides a useful summary of the methods for assessing permanent impairment arising from respiratory disorders.
8.2 The level of impairment arising from conditions that are not work-related needs to be assessed by the medical assessor and taken into consideration in determining the level of permanent impairment. The level at which pre-existing conditions and lifestyle activities, such as smoking, contribute to the level of permanent impairment requires judgement on the part of the clinician undertaking the impairment assessment. The manner in which any deduction for these is applied needs to be recorded in the assessing specialist’s report.
Examinations, clinical studies and other tests for evaluating respiratory disease (AMA5 Section 5.4)
8.3 AMA5 tables 5-2b, 5-3b, 5-4b, 5-5b, 5-6b and 5-7b (pp 95–100) give the lower limits of normal values for pulmonary function tests. These are used in AMA5 Table 5-12 (p 107) to determine the impairment classification for respiratory disorders.
8.4 Classes 2, 3 and 4 in Table 5-12 list ranges of whole person impairment (WPI). The assessor should nominate the nearest whole percentage based on the complete clinical circumstances when selecting within the range.
Asthma (AMA5 Section 5.5)
8.5 In assessing permanent impairment arising from occupational asthma, the assessor will require evidence from the treating physician that:
- at least three lung function tests have been performed over a six-month period and that the results were consistent and repeatable over that period
- the worker has received maximal treatment and is compliant with his or her medication regimen.
8.6 Bronchial challenge testing should not be performed as part of the impairment assessment. Therefore, in AMA5 Table 5-9 (p 104), ignore column 4 (PC20 mg/mol or equivalent, etc.).
8.7 Permanent impairment due to asthma is rated by the score for the best post-bronchodilator forced expiratory volume in one second (FEV1) (score in column 2, AMA5 Table 5-9) plus per cent of FEV1 (score in column 3) plus minimum medication required (score in column 5). The total score derived is then used to assess the per cent impairment in AMA5 Table 5-10 (p 104).
Obstructive sleep apnoea (AMA Section 5.6)
8.8 This section needs to be read in conjunction with AMA5 sections 11.4 (p 259) and 13.3c (p 317).
8.9 Before permanent impairment can be assessed, the person must have appropriate assessment and treatment by an ear, nose and throat surgeon and a respiratory physician who specialises in sleep disorders.
8.10 The degree of permanent impairment due to sleep apnoea should be calculated with reference to AMA5 Table 13-4 (p 317).
Hypersensitivity pneumonitis (AMA5 Section 5.7)
8.11 Permanent impairment arising from disorders included in this section are assessed according to the impairment classification in AMA5 Table 5-12 (p 107).
Pneumoconiosis (AMA5 Section 5.8)
8.12 This section is excluded from the Guidelines, as these are the subject of the Dust Diseases Legislation.
Lung cancer (AMA5 Section 5.9)
8.13 Permanent impairment due to lung cancer should be assessed at least six months after surgery. AMA5 Table 5-12 (p 107), not Table 5-11, should be used for assessment of permanent impairment.
8.14 Persons with residual lung cancer after treatment are classified in respiratory impairment class 4 (AMA5 Table 5-12).
Permanent impairment due to respiratory disorders (AMA5 Section 5.10)
8.15 AMA5 Table 5-12 should be used to assess permanent impairment for respiratory disorders. The pulmonary function tests listed in Table 5-12 must be performed under standard conditions. Exercise testing is not required on a routine basis.
8.16 An isolated abnormal diffusing capacity for carbon monoxide (DCO) in the presence of otherwise normal results of lung function testing should be interpreted with caution and its aetiology should be clarified.