Friday, November 9, 2007

Rudy Giuliani, amateur epidemiologist

There have been many articles written about poor use of prostate cancer statistics by Rudy Giuliani. The main complaint is that he uses faulty logic to calculate prostate cancer survival rates. However, I think the bigger problem with Giuliani's numbers is that he cherry picks numbers to prove his points, providing no context. Once again, this appears to be a complicated issue and simplistic analysis by a politician.

First, here's the background. According to a Giuliani radio ad:

"I had prostate cancer, five, six years ago. My chance of surviving prostate cancer, and thank God I was cured of it, in the United States, 82 percent. My chances of surviving prostate cancer in England, only 44 percent under socialized medicine."

As pointed out by and The Fact Checker at the Washington Post, the 44% figure was arrived at by simplistically dividing per capita prostate cancer mortality by per capita prostate cancer diagnoses (and subtracting that figure from 100%). Unfortunately, the people diagnosed in a given year are not the same people that die in that year, so you can't figure out what your odds of surviving prostate cancer by using this data. To determine survival rate, you need to follow the same population over a period of time (5-year survival rate is the standard metric). The 5-year survival rate in the U.K. is 74.4%.

The bigger problem
Clearly, it is troubling that a guy who wants to be part of the debate on the nation's health care doesn't have anyone on his staff that really understands the data. Equally troubling is that even after the doctors whose study he bases his claims pointed out his error, he continued to use the misleading numbers. But even if Giuliani used the proper numbers (which are 5-year survival rates of 74% in the U.K. and 98% in the U.S.), the conclusion he draws is simplistic at best.

Let me give you some statistics that would seem to refute Giuliani's conclusion about socialized medicine:
Does this mean that socialized medicine is better than private medicine? In my opinion, that would be an equally simplistic conclusion. We need to control for a lot of things in order for the data to be meaningful: population demographics, approach toward prevention, detection and treatment, etc. Unfortunately, intellectually honest analysis doesn't seem to be a Giuliani strong point.