The combined WPI (CWPI) is a percentage figure which is the result of the combination of two or more WPI ratings using the Table 14.1 - Combined Values Chart in Chapter 14 of the DRCA PI Guide.
As previously discussed in chapters 3 and 4, the High Court decision in Canute must be considered when determining which impairment values, if any, should be combined. The discussion of combined values in the 'Principles of Assessment' in the Approved Guide can no longer be applied to all cases.
Canute states that there should be a separate assessment of the degree of permanent impairment resulting from each separate injury suffered by a person. This includes injuries which arise from, occur subsequent to, or are caused by the initial injury or associated treatment. Post-Canute, the only scenario where impairments would be combined using the combined values chart is where a single injury resulted in multiple impairments e.g. a single spinal cord injury resulting in the loss of function of the lower extremities, loss of urinary and reproductive functions.
Delegates need to be careful in making the distinction between injury and impairment, as multiple injuries, even if they arise from the same event, are not combined. This must be determined on the basis of the medical evidence.