Conditions (1)–(3) allow us to represent utility as the sum of identical per-period utility functions (as required by the QALY model).
This also allows us to find WTP by summing period-specific WTP figure across periods.
For a link between CBA and CEA, we must have a constant WTP-per-QALY.
We proceed by showing that this is impossible under all of Conditions (1)–(5).
period-specific
across periods