The combined WPI (CWPI) is a percentage figure which is the result of the combination of two or more WPIs using the Combined Values Chart (Part 2 Appendix 1, previously Table 14.1) in the Approved Guide.
As previously discussed in chapters 3 and 4, the Canute decision 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, as reinforced by Robson, 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 and Robson, 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. In any case, this must be determined on the basis of the medical evidence.