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NSW workers compensation guidelines for the evaluation of permanent impairment

These guidelines explain permanent impairment assessment in the NSW workers compensation system. This is the fourth edition of these guidelines, published in April 2016.

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The State Insurance Regulatory Authority (SIRA) has issued the 4th edition of the NSW workers compensation guidelines for the evaluation of permanent impairment (Guidelines) for assessing the degree of permanent impairment arising from an injury or disease within the context of workers’ compensation. When a person sustains a permanent impairment, trained medical assessors must use the Guidelines to ensure an objective, fair and consistent method of evaluating the degree of permanent impairment.

The Guidelines are based on a template that was developed through a national process facilitated by Safe Work Australia. They were initially developed for use in the NSW system and incorporate numerous improvements identified by the then WorkCover NSW Whole Person Impairment Coordinating Committee over 13 years of continuous use. Members of this committee and of the South Australia Permanent Impairment Committee (see list in Appendix 2) dedicated many hours to thoughtfully reviewing and improving the Guidelines. This work is acknowledged and greatly appreciated.

The methodology in the Guidelines is largely based on the American Medical Association’s Guides to the Evaluation of Permanent Impairment, 5th Edition (AMA5). The AMA guides are the most authoritative and widely used in evaluating permanent impairment around the world. Australian medical specialists representing Australian medical associations and colleges have extensively reviewed AMA5 to ensure it aligns with clinical practice in Australia.

The Guidelines consist of an introductory chapter followed by chapters dedicated to each body system.

The Introduction is divided into three parts. The first outlines the background and development of the Guidelines, including reference to the relevant legislative instrument that gives effect to the Guidelines. The second covers general assessment principles for medical practitioners applying the Guidelines in assessing permanent impairment resulting from work-related injury or disease. The third addresses administrative issues relating to the use of the Guidelines.

As the template national guideline has been progressively adapted from the NSW Guideline and is to be adopted by other jurisdictions, some aspects have been necessarily modified and generalised. Some provisions may differ between different jurisdictions. For further information, please see the Comparison of Workers’ Compensation Arrangements in Australia and New Zealand report, which is available on Safe Work Australia’s website.

Publications such as this only remain useful to the extent that they meet the needs of users and those who sustain a permanent impairment. It is, therefore, important that the protocols set out in the Guidelines are applied consistently and methodically. Any difficulties or anomalies need to be addressed through modification of the publication and not by idiosyncratic reinterpretation of any part. All queries on the Guidelines or suggestions for improvement should be addressed to SIRA at contact@sira.nsw.gov.au.

12. The endocrine system

AMA5 Chapter 10 (p 211) applies to the assessment of permanent impairment of the endocrine 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.

Introduction

13.1 AMA5 Chapter 10 provides a useful summary of the methods for assessing permanent impairment arising from disorders of the endocrine system.

13.2 Refer to other chapters in AMA5 for related structural changes – the skin (eg pigmentation, in Chapter 8), the central and peripheral nervous system (eg memory, in Chapter 13), the urinary and reproductive system (eg infertility renal impairment, in Chapter 7), the digestive system (eg dyspepsia, in Chapter 6) and the cardiovascular system (in chapters 3 and 4) and visual system (Chapter 8 AMA4).

13.3 The clinical findings to support the impairment assessment are to be reported in the units recommended by the Royal College of Pathologists of Australia. (See Appendix 13.1).

13.4 Westergren erythrocyte sedimentation rate (WSR) is equivalent to ESR.

Adrenal cortex

13.5 AMA5 (p 222) first paragraph: disregard the last sentence, ‘They also affect inflammatory response, cell membrane permeability, and immunologic responses, and they play a role in the development and maintenance of secondary sexual characteristics’. Replace with: ‘Immunological and inflammatory responses are reduced by these hormones and they play a role in the development and maintenance of secondary sexual characteristics.’

13.6 AMA5 example 10-18 (pp 224–25): See reference to ESR (paragraph 13.4, above).

13.7 AMA5 example 10-20, regarding history (p 225): Instead of ‘hypnotic bladder’, read ‘hypotonic bladder’.

Diabetes mellitus

13.8 AMA5 (p 231): refer to the Australian Diabetes Association Guidelines with regard to levels of fasting glucose. (The position statement from the Australian Diabetes Society is reprinted in Appendix 13.2).

13.9 AMA5 (p 231): At the end of the second paragraph insert, ‘The goal of treatment is to maintain haemoglobin A1c within 1% of the normal range (4.0–6.3%)’.

Mammary glands

13.10 AMA5 example 10-45, regarding current symptoms (p 239): Disregard the last sentence, ‘Both bromocriptine and cabergoline cause nausea, precluding use of either drug’. Replace with: ‘Routine use of bromocriptine and cabergoline is normal in Australia. It is rare that nausea precludes their use’.

Criteria for rating permanent impairment due to metabolic bone disease

13.11 AMA5 (p 240): Impairment due to a metabolic bone disease itself is unlikely to be associated with a work injury and would usually represent a pre-existing condition.

13.12 Impairment from fracture, spinal collapse or other complications may arise as a result of a work injury associated with these underlying conditions (as noted in AMA5 Section 10.10c) and would be assessed using the other chapters indicated, with the exception of Chapter 18, on pain, which is excluded from the Guidelines.

Appendix 13.1: Interpretation of pathology tests

From the Manual of use and interpretation of pathology tests, 3rd edition. Reprinted with kind permission of the Royal College of Pathologists of Australasia.

Reference ranges, plasma or serum, unless otherwise indicated

Alanine aminotransferase (ALT)(adult)<35 U/L
Albumin(adult)32-45 g/L
Alkaline phosphatase (ALP)(adult, non-pregnant)25-100 U/L
Alpha fetoprotein(adult, non-pregnant)<10 g/L
Alpha-1-antitrypsin 1.7-3.4 g/L
Anion gap 8-16 mmol/L
Aspartate aminotransferase (AST) <40 U/L
Bicarbonate (total CO2) 22-32 mmol/L
Bilirubin (total)(adult)<20 μmol/L
Calcium(total)2.10-2.60 mmol/L
 (ionised)1.17-1.30 mmol/L
Chloride 95-110 mmol/L
Cholesterol (HDL)(male)0.9-2.0 mmol/L
 (female)1.0-2.2 mmol?L
Cholesterol (total) (National Heart Foundation (Australia) recommendation)<5.5 mmol/L
Copper 13-22 μmol/L
Creatine kinase (CK)(male)60-220 U/L
 (female)30-180 U/L
Creatinine(adult male)0.06-0.12 mmol/L
 (adult female)0.05-0.11 mmol/L
Gamma glutamyl transferase (GGT)(male)<50 U/L
 (female)<30 U/L
Globulinadult25-35 g/L
Glucose(venous plasma) - (fasting)
(venous plasma) - (random) 
3.0-5.4 mmol/L
3.0-7.7 mmol/L 
Lactate dehydrogenase (LD)(adult)110-230 U/L
Magnesium(adult)0.8-1.5 mmol/L
Osmolality(adult)280-300 m.osmoll/kg water
pCO2(arterial blood)4.6-6.0 kPa (35-45 mmHg)
pH(arterial blood)7.36-7.44 (36-44 nmol/L)
Phosphate 0.8-1.5 mmol/L
pO2(arterial blood)11.0-13.5 kPa (80-100 mmhg)
Potassium(plasma)3.4-4.5 mmol/L
 (serum)3.8-4.9 mmol/L
Prolactin(male)150-500 m U/L
 (female)0-750 m U/L
Protein, total(adult)62-80 g/L
Sodium 135-145 mmol/L
Testosterone and related androgensSee Table A below

Table A: Reference intervals for testosterone and related androgens (serum)

 MaleFemale
Pre-pubertalAdult (age related)Pre-pubertalAdult (age related)
Free testosterone (pmol/L) 170-510 <4.0
Total testosterone (nmol/L)<0.58-35<0.5<4.0
SHBG (nmol/L)55-10010-5055-10030-90 (250-500 in the third trimester)
Dihydrotestosterone (nmol/L) 1-2.5 

Reference ranges, whole blood

Haemoglobin (Hb)(adult male)
(adult female) 
130-180 g/L
115-165 g/L 
Red cell count (RCC)(adult male)
(adult female)
4.5-6.5 x 1012/L
3.8-5.8 x 1012/L 
Packed cell volume (PCV)(adult male)
(adult female)
0.40-0.54
0.37-0.47 
Mean cell volume (MCV) 80-100 fL
Mean cell haemoglobin (MCH) 27-32 pg
Mean cell haemoglobin concentration (McHC) 300-350 g/L
Leucocyte (white cell) count (WCC) 4.0-11.0 x 109/L

Leucocyte differential count

  • Neutrophils
  • Eosinophils
  • Basophils
  • Monocytes
  • Lymphocytes

Platelet count

 

2.0-7.5 x 109/L
0.04-0.4 x 109/L
<0.1 x 109/L
0.2-0.8 x 109/L
1.5-4.0 x 109/L
150-400 x 109/L 
Erythrocyte sedimentation rate (ESR)male 17-50 yrs
male >50 yrs
female 17-50 yrs
female >50 yrs 
1-10 mm/hour
2-14 mm/hour
3-12 mm/hour
5-20 mm/hour 
Reticulocyte count 10-100 x 109/L
(0.2-2.0%)

Reference ranges, citrated plasma

Activated partial thromboplastin time (APTT)

  • Therapeutic range for continuous infusion heparin

25-35 seconds

1.5-2.5 x baseline

Prothrombin time (PT)11-15 seconds

International normalised ration (INR)

  • Therapeutic range for oral anticoagulant therapy


1.0-4.5 
Fibrinogen1.5-4.0 g/L

Reference ranges, serum

Rheumatoid factor (nephelometry)<30 IU/L
C30.9-1.8 g/L
C40.16-0.50 g/L
C-reative protein<5.0 mg/L

Immunoglobin:

  • IgG
  • IgA
  • IgM


6.5-16.0 g/L
0.6-4.0 g/L
0.5-3.0 g/L

Reference intervals for lymphocyte subsets

 Adult
Total lymphocytes1.5-4.0
CD30.6-2.4
CD4 (T4)0.5-1.4
CD8 (T8)0.2-0.7
CD190.04-0.5
CD160.2-0.4
CD4/CD8 ratio1.0-3.2

Appendix 13.2: New classification and criteria for diagnosis of diabetes mellitus