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, an assessor 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 (ie. likely to continue indefinitely) but not yet stable (eg. 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 gradual deterioration is expected, a s 25 payment may be made, but it 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 assessor 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 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 s 25 based on the lower WPI.
In such cases, the WPI entered here should be the minimum eventual impairment anticipated if the treatment is entirely successful.