Tuesday, September 25, 2012

Quality adjusted life years (QALY)-More to life than counting the dead

Counting deaths is much easier than assessing quality of life.Drs Pamela Hartzband and Jerome Groopman discuss the vagaries and uncertainly of clinical decision analysis and in quantifying the impact of disease on a person's life in the September 13,2012 issue of NEJM in a perspective piece entitled There is More to Life than Death.

The authors point out in regard to the recent USPTF pronouncement regarding PSA testing that while the data are conflicting and the study (the PLCO trial) that largely controlled the panel's decision against PSA testing has serious defects the chairperson spoke as if the call was a slam dunk or in her words "a no brainer". The authors of the NEJM article were polite in their criticism. but I cannot talk about the panel's actions and comments without using the word hubris. Reasonable, well trained statisticians have differed in their analysis of the set of data on PSA testing. Actually hubris is not strong enough a descriptor.

The Harvard husband and wife team asks " Is it possible to put numbers on the "utility"or impact of these conditions on a man's life? Is the concept of aggregating utility valid? I have argued before that it is not. See here.

Hartzband and Groopman discuss methods to attempt to quantify utility. One such method is call the "time trade off". Here a person is simply asked how many years of life she would be willing to give up to reverse a medical condition and return to health. On the face of it this is a absurd counter factual. One is asked to imagine having for example a cancer and what number of years of life they would give up to not have the cancer? A similar absurdity is the "standard gamble" which asks which odds you would take to risk sudden death to reverse some condition.

H and G :

"People cannot anticipate the global impact of a specific future change in their lives".

Of course they cannot.The quality adjusted life years concept is built on a dual fallacy.The fallacy of determining of some one else"s quality of life-based on a hypothetical and the absurdity of adding those determinations to conjure up; some aggregate utility. Yet organizations such as ACP seems to proceed on making cost effectiveness "determinations" that likely will be used to limit a person's access to some element of medical care.Are they aware that the father of utilitarianism expressed the folly of adding up happiness (or the modern equivalent - utility)?

At least the authors of an Annals of Internal Medicine article hyping the cost effectiveness analysis did not claim their analysis were no brainers but rather assured the reader that those type decisions were complex and needed to be made by highly trained professionals.This meant training more advanced that the 7-10 years of post college education that a physician accumulates.The tone of the article made it clear than the Annals article authors were just the folks for that type of very difficult analysis.No hubris there.

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