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4.5.2 When is an Impairment Stable?

Last amended 
29 July 2021

Essentially, it is a matter of fact and medical evidence when an impairment becomes stable for the purposes of compensation for permanent impairment. In order to determine the appropriate date, a delegate should, in particular, look for two items of evidence:

  • medical opinions establishing a date when the impairment stabilised, and
  • the last date of any active treatment of the impairment.

It is important to note that there is a difference between the date an impairment became stable and the date of permanent impairment. An impairment may well be permanent (i.e. likely to continue indefinitely) but not yet stable (e.g. a back injury where a disc has ruptured and the client's condition is still deteriorating). Similarly, an impairment could be stable, but not yet permanent, because it is likely that treatment will resolve the condition.

Where further deterioration is expected

Where a condition is permanent and stable at the current level of impairment however a gradual deterioration is expected, for example degenerative conditions, a final assessment under Section 24 should be made. The assessment must be based on the current actual degree of impairment and not on the expected degree of impairment after the deterioration has occurred. Under no circumstances is a decision to be made on the basis of an anticipated worsening of an impairment

Where reasonable medical treatment may affect the degree of impairment

When deciding if an impairment is stable, the delegate must consider whether reasonable medical treatment may alter the degree of impairment. If medical treatment is likely to alter the degree of impairment, the impairment is not stable.

If reasonable medical treatment is expected to reduce the degree of impairment, but there would still be a compensable degree of impairment after the treatment, an interim payment may be made under S25 based on the lower WPI.

In such cases, the WPI used here should be the minimum eventual impairment anticipated if the treatment is entirely successful. As the Tribunal found in Dimitriou and Comcare (1997) AATA 583:

There may well be a basis to find that that degree of whole person impairment presently is greater than 10 per cent however we have preferred to find an impairment at 10 per cent only so as to ensure that should the applicant undertake surgery into the future, her impairment following that surgery will be no less than what we would otherwise presently decide. That is to say, we would be hopeful that in the event of the applicant successfully undertaking hip replacement that her whole person impairment then would be less than 20 per cent. As we have indicated above we are satisfied that at the present time and in the event of successful surgery the whole person impairment will be no less than 10 per cent.   

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Significant delay in stabilisation of an impairment – 1930 Act

If a 1930 Act permanent impairment became stable after the commencement of the 1971 Act on 1 September 1971, the applicable rate is determined under the 1971 Act.    

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