# Standard Gamble is now becoming real life

An article in the NY Times  highlights an interesting development in which a theoretical construct is becoming an actual reality.  The article describes how immunotherapy is being tested in patients with melanoma.  Several drugs seem to result in some improvement in survival and combinations of drugs result in more drastic improvements.  However, these combinations can be lethal (in one test 3/46 died from the drugs), as well as causing myriad side-effects.

In decision theory, there is a concept of “utility” which is basically a quantitative measure of how much one values something.  In economic terms, this value is relatively easy to assess since you are usually dealing with either actual money or something with monetary value.  In health care, it is not so straightforward.  Would you rather live 10 years with pain or 5 years without?  One way of trying to assess these utilities when the outcome is uncertain (as it always is in medicine) is called the Standard Gamble.  Imagine trying to assess how someone values a given health state, for example living with “dry mouth” which  may limit how well you can swallow and eat certain foods.  In this test, the person is given a choice: (a) live the rest of your life with dry mouth, or (b) take a pill which has a probability, P, of curing you but also a probability, 1-P, of killing you instantly.  Let’s start off with P = 90%.  That is, if you take the pill, there is a 90% chance you will be cured of dry mouth for the rest of your life.  Do you take the pill with its 10% chance of dying or do you live the rest of your life with your condition?  The test consists of varying the probability, P, until the person cannot choose between them.  That value of P is then called the “utility for the condition of dry mouth.”

We now have the situation where patients (and physicians) can choose between a situation where the outcome is pretty well-known or trying a new therapy which has the promise of making things much better but can also kill you.  Now the situation is not exactly the same as the Standard Gamble since the new therapy brings with it some new complications even if they are not fatal.  But it does make one think of whether we can use data from these real life situations to study how utilities are measured.