By Larry Marsh, Kansas City Star Midwest Voices columnist 2009

What would you think of a financial adviser who ran simulations for you using the average investor’s numbers instead of your own? Worse, what if your tax preparer just filled in your tax forms with the average taxpayer’s information instead of your specifics?

By analogy, that’s what the medical profession is doing. Your doctor wants to treat you as an individual, but in practice it often isn’t working out that way.

There is a way to substantially improve medical care while significantly reducing costs. The key is how the information from medical studies is actually used in practice.

Your doctor records your personal and family medical history and orders all sorts of tests and scans. She intends to treat you as a unique individual. But when she turns to the medical literature, it’s strictly one-size-fits-all.

Physicians interact routinely with drug company representatives, attend conferences and seminars, and have periodic update sessions with medical researchers.

The problem is that physicians are told things such as a 1 percent reduction in cholesterol will lead on average to a 2 percent reduction in the probability of a heart attack.

But who is this Joe or Jill Average they are talking about?

The equations that come from medical research typically use averages from a sample of people. In calculating your probability of dying from a disease, plugging in Joe Average’s numbers instead of your own limits its relevance to you.

For example, the impact of cholesterol on the probability of a heart attack might depend on the iron level in the blood. Iron oxygenizes cholesterol, making it stickier and easier to cling to the walls of your arteries. A pre-menopausal woman tends to have less iron in her blood so the same level of cholesterol is less dangerous for her than for a post-menopausal woman or a man.

Researchers typically substitute the average iron level over all patients in their studies for research journals or sponsors.

They do this with all the variables, except for cholesterol. In other words, they simulate a one percent reduction in cholesterol using Joe Average’s numbers for all the other variables.

It would be a lot more accurate to plug in a specific patient’s numbers for iron and all the other variables in the model, but researchers know that the doctors are short of time and don’t have access to medical software that could personalize the analysis. Maybe you’re a heart attack waiting to happen, or maybe your chances of a heart attack are quite small. You won’t know unless they plug in your numbers.

President Barack Obama already got a provision in the stimulus bill to provide funding to digitize patient data. This will make your data much easier to analyze.

A medical software company such as Cerner Corp. could get information from the authors of medical studies that would enable it to more accurately assist doctors in a diagnosis, including red-flagging patients at high risk for a particular illness.

You need to ask your doctor to have your data analyzed. We all need to do this.

Doctors should take the initiative and ask for this service. Then they will have time to study the results and incorporate their own first-hand knowledge and experience before choosing specific treatment plans.

Until we start asking for this service, it will not become available.

Larry Marsh is professor emeritus (retired) at the University of Notre Dame, where he taught statistical methods for 30 years. He lives in Kansas City. To reach him, send e-mail to or write to him c/o The Editorial Page, The Kansas City Star, 1729 Grand Blvd., Kansas City, MO. 64108

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