People who are more wealthy spend more, and people who are less wealthy spend less, and it happens throughout the wealth distribution. Therefore, it is necessary to model all of those things.
With an ex post measure of outcomes, when comparing outcomes in spending with economic resources, if available economic resources fall below some level, however that is done, it is a very straightforward situation to explain to people. No modeling is needed. The data will allow one to integrate over all the insurance packages and economic positions that people occupy and take account of the covariances between their economic position and their health status and family situations.
Developing the ex ante risk index would be like developing a poverty index to predict that next year X numbers or a fraction of people are going to be in poverty. That is not of interest. Of interest is saying that X many people were in poverty this year and being able to explain it. He suggested that the same should happen with the MCER index.