Sigma-Aldrich Pty Ltd v Ratanasirilak

[2022] NSWPICMP 426

DETERMINATION OF APPEAL PANEL
CITATION:	Sigma-Aldrich Pty Ltd v Ratanasirilak [2022] NSWPICMP 426
APPELLANT:	Sigma-Aldrich Pty Ltd
RESPONDENT:	Pricha Ratanasirilak
Appeal Panel
MEMBER:	Richard Perrignon
MEDICAL ASSESSOR:	Dr Gregory Kaufman
MEDICAL ASSESSOR:	Dr David Crocker
DATE OF DECISION:	26 October 2022
CATCHWORDS:	wORKERS cOMPENSATION - Appeal from assessment of whole person impairment (WPI) (respiratory system, sleep apnoea); whether Medical Assessor erred in assessing a class 2 impairment failing in circumstances where the worker admitted that his sleep apnoea did not have any significant impact on his activities of daily living (ADLs); whether he erred in selecting a 15% WPI from the range of 10% to 29% provided by Table 13-4 of the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th ed (AMA5) in circumstances where he found that the impact on ADLs was predominantly caused by the condition of the lumbar spine; Held – Medical Assessment Certificate confirmed.

BACKGROUND TO THE APPLICATION TO APPEAL

1. The appellant employer appeals from the Medical Assessment Certificate of Medical Assessor Burns dated 4 July 2022.

2. Medical Assessor Burns assessed a 22% whole person impairment (14% lumbar spine, 8% respiratory system – sleep apnoea, scarring 1%) as a result of injury on 18 May 2015, when Mr Ratanasirilak injured his lumbar spine at work.

3. Medical Assessor Burns found that the medications he was taking for the lumbar spine condition aggravated a pre-existing condition of sleep apnoea, and assessed the respiratory system in accordance with Table 13-4 of AMA5. He selected a Class 2 impairment, which provides a range of 10% to 29% whole person impairment. From that range, he selected 15% as the appropriate impairment rating, and deducted one half for the effects of pre-existing sleep apnoea. This yielded 7.5% whole person impairment, which he rounded up to 8% whole person impairment.

4. The respondent employer alleges demonstrable error and the application of incorrect criteria in respect of the assessment of sleep apnoea only. It does not allege error in the deduction of one half for a pre-existing condition, but submits that the evidence justified a class 1 impairment rather than class 2.

5. Professor Thomas, on whose assessment the employer had relied, assessed a class 1 impairment in February 2022. Dr Freiberg, on whose assessment the worker had relied, assessed a class 3 impairment in August 2021.

6. The Appeal Panel conducted a preliminary review of Medical Assessor Burns’ medical assessment in the absence of the parties and in accordance with the NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment (4th edition) (the Guidelines).

Submissions

1. The parties made written submissions which have been taken into account. It is unnecessary to repeat them in full. A brief summary follows.

2. The appellant’s submissions, though divided into numbered paragraphs, do not attempt to define separate grounds of appeal. Doing our best, the grounds seem to fall into the two categories summarised below. The appellant submits that the Medical Assessor erred in the following ways in assessing sleep apnoea:

   (a)    by failing to give adequate reasons for selecting a class 2 impairment, in circumstances where the worker admitted that his sleep apnoea did not have any significant impact on his activities of daily living, justifying a class 1 impairment, and

   (b)    by failing to provide adequate reasons for selecting a 15% whole person impairment from the range of 10% to 29% provided by Table 13-4, in circumstances where the assessor found that the impact on activities of daily living was predominantly caused by the condition of the lumbar spine.

3. The respondent submits as follows in reply:

   (a)    Table 13-4 sets out the criteria for selecting a class 1 impairment, as opposed to a class 2 impairment. Class 1 requires that an individual can perform most activities of daily living. Class 2 requires that the condition interferes with the ability to perform some of those activities. This provides an assessor with a ‘very wide discretion’ as the selection of the appropriate class, based on the degree to which the disorder affects the activities of daily living;

   (b)    the selection of a percentage impairment within the range provided by class 2 is matter for the assessor’s discretion, which is also very wide;

   (c)    the Medical Assessor found that the disorder will impact upon some activities of daily living. This finding satisfied the criteria for a class 2 impairment;

   (d)    the assessor also found that most of the impact on activities of daily living was caused by the lumbar spine condition. This finding does not prevent the criteria for class 2 being satisfied in respect of sleep apnoea;

   (e)    it was open to the Medical Assessor to find, as he did, that the level of impairment fell toward the bottom of the prescribed range. It was therefore open to him to select a 15% whole person impairment, and

   (f)    the assessor was not bound to accept the assessment of Professor Thomas.

Selection of a class 2 impairment

1. In respect of the respiratory system, the task of the Medical Assessor was to make a diagnosis, to determine whether there was a causal link between the diagnosed condition and injury, to assess the resulting impairment by applying the criteria in Table 13-4 and selecting the appropriate impairment class, and to assess the degree of impairment from the range of impairments within that class.

2. As indicated, Assessor Burns diagnosed a condition of sleep apnoea. He found that the condition had been aggravated by medication used to treat the lumbar spine injury. There is no appeal from that finding.

3. He then applied the criteria in Table 13-4 to determine the appropriate impairment class. The criteria for classes 1 and 2 were as follows – emphasis added.

Class 1	Reduced daytime alertness; sleep pattern such that individual can perform most activities of daily living
Class 2	Reduced daytime alertness; interferes with ability to perform some activities of daily living

1. In both classes, the first criterion is that there be reduced daytime alertness. The difference, if any, lies in the second criterion. That criterion is worded differently in each case, but it seems to us that the two are not necessarily mutually exclusive. It is possible for a person to be able to perform most activities of daily living (class 1), while not being able to perform some of them (class 2).

2. This Panel must decide whether the selection of a class 2 impairment constituted demonstrable error or the application of incorrect criteria, as alleged.

3. Assessor Burns provided the following reasons for his assessment at [10b]:

   “With respect to his respiratory system (sleep apnoea) I note that under the New South Wales Guidelines, paragraph 8.10 that sleep apnoea is to be assessed using Table 13-4 of the 5th Edition of the AMA Guides.  From that Table I believe that he would currently fall in Class 11 [sic, Class 2] though I believe the sleep apnoea may impact upon some of his activities of daily living but not many.  These are mostly impacted by his lumbar spine.  Within Class 11 [sic, 2] I would assess him as 15% whole person impairment.”

4. Dr Burns recorded the following impacts on activities of daily living at [4] under the heading, “Social activities/ADL”:

   “He lives in a house and states that he cannot do the lawnmowing or any of the outdoor duties.  His wife is his full time carer and is currently receiving a carers allowance.  She does all of the cooking and cleaning around the house and the majority before the current accident.  He did report that he is independent in self-care.”

5. He recorded the following history at [4] under the heading, “Present symptoms” – emphasis added:

   “With respect to his sleep apnoea he reported that he has ongoing day time sleepiness but this is not giving him any significant impact on his activities of daily living.  These are impacted mostly by his severe low back pain.”

6. With respect to Dr Frieberg’s assessment, he explained at [10c] – emphasis added:

   “I believe that Dr Frieberg has overestimated the impact of his obstructive sleep apnoea on his day to day activities.  The vast majority of these on my discussion with Mr Ratanasirilak are in fact due to his low back injury and his ongoing severe pain. In fact, it would appear that his pain, which has given him disruption of his sleep as well.  I therefore believe that he would be placed towards the bottom end of Class 11 [sic, 2] rather than in Class 111 [sic, 3] for the sleep apnoea alone.”

7. Reading that passage together with the finding that daytime sleepiness was not having a ‘significant’ impact on activities of daily living and with the reasons given by the Medical Assessor at [10b], we interpret him to mean that sleep apnoea affected at least some of the activities of daily living, even though most of the adverse effects on activities of daily living were caused by the condition of the lumbar spine. That finding was sufficient, in our view, to satisfy the criteria in class 2 that the sleep apnoea ‘interferes with [the worker’s] ability to perform some activities of daily living’.

8. It follows that it was open to the assessor to select a class 2 impairment as he did. Sufficient reasons were given. We can identify no error or the application of incorrect criteria.

Selection of a 15% whole person impairment

1. Table 13-4 provides that a class 2 impairment encompasses whole person impairment in the range from 10% to 29%. It provides no criteria for distinguishing between each percentage.

2. The selection of a particular percentage is an evaluative exercise to be conducted by the assessor, assessing the degree or severity or impairment using his or her clinical judgment.

3. This is what the assessor did. Using his clinical judgment, he assessed the level of impairment as falling “towards the bottom end” of class 2. Having made that finding, it was reasonably open to him to select 15% as the appropriate degree of whole person impairment. His reasons were clear enough: the impairment lay toward the bottom end of the range, and in his clinical judgment 15% was appropriate.

4. That assessment was not inconsistent with the finding that the impact on activities of daily living was predominantly caused by the condition of the lumbar spine.

5. We can identify neither error nor the application of incorrect criteria. This ground fails.

Conclusion

26. For the reasons given, the appeal is dismissed, and the Medical Assessment Certificate of Medical Assessor Burns is confirmed.