"ALL CAPS IN DEFENSE OF LIBERTY IS NO VICE."

Thursday, November 01, 2007

Prostate cancer in Britain and the USA

A comment from Britain's Financial Times:

Paul Krugman has attacked Rudy Giuliani for a dishonest ad on health care--or perhaps an ignorant one, as the case may be. This is a test for the media, as well as a scandal in its own right, Paul says. Will those feckless reporters and editors at The New York Times call Giuliani to account for this? Probably not, seems to be Paul's opinion:
OK, Rudy Giuliani has just released an ad claiming that the survival rate from prostate cancer is much higher in America than in Britain, thus proving the failure of socialized medicine.

The problem is that his claim is just plain false. In fact, mortality rates from prostate cancer are almost the same in America and Britain.

So, will this get as much attention as, say, the Edwards haircut or the Hillary laugh? Will it get any coverage at all? Bear in mind that health care is the central domestic issue of this election — and Rudy has just showed that he doesn’t know a thing about it.

Giuliani's claims in the ad are indeed misleading. First, prostate cancer is a very bad example. Worse, in my view, is the implication that his Democratic opponents are proposing "socialised medicine" remotely similar to  Britain's NHS. That can only be a deliberate deception.

To say that prostate cancer survival rates are much higher in the US than in England is not "just plain false", however. It is just plain true. Five-year survival rates are higher in both America and England than Giuliani said. In the United States they stand at close to 100 per cent. In England they are 25 points lower. Figures for prostate cancer are notoriously misleading, though, because early detection (at which the US excels) delivers little improvement in mortality.

Chiefly because of better diagnosis, America records a far higher incidence of prostate cancer--and nearly all of those early-detected cases survive five years. Men with prostate cancer, which develops slowly, often die of something else. If you are a man with prostate cancer, it may not matter very much whether your cancer is diagnosed early, or whether you live in Britain or America.

But does Paul therefore think that cancer survival rates, correctly measured, are similar for all cancers, including those for which early detection is important? If so, he is mistaken. See this report, entitled "Cancer Survival Rates Improving Across Europe, But Still Lagging Behind United States" (and remember that England's rates, not broken out, are among the worst in Europe).

Taking recent figures, female five-year cancer survival rates are 62.9 per cent on average in the US and 52.7 per cent in England. To compare America's privately insured with England's NHS patients, you'd need to bump up that American survival rate a bit (the uninsured most likely have lower survival rates--otherwise why worry about universal coverage) and bump down the English one (because some Brits have private insurance, and so buy better care).

Nationally, American cancer survival rates are significantly better. Certainly not by the 40-point margin Giuliani implied, but still. And the politically salient question is this: If you have cancer, would you rather be an American with insurance or an Englishman without? The answer is obvious.

Source


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3 comments:

Matthew said...

Fantastic. Now do the same analysis for kidney transplants, diabetic foot amputation rates, cardiac care, etc, etc.

You'll find the answers are all over the map. And on most indicators the US looks a lot worse not better than other countries.

Oh, other than we spend double what the Brits spend and 50% more than everyone else.

I am just waiting for Hillary to lose it with Rudy on this schlock

Unknown said...

There are several problems with using cured/diagnosed ratio or survival data when comparing UK vs US (or any two groups where onbe group is screened a lot more than the other): these numbers are affected by overdiagnosis, lead-time bias and length bias. This is not only a case with prostate, but with other cancers as well, for example, mammography guidelines are different in the US and the UK: UK screenes women 50-70 biennially. While mammography does reduce mortality from the desease, there is still a lot of questions if the US screening compared to the UK is beneficial. Additionally, the oversiagnosis in mammography is an accepted fact with estimates ranging from 5 to 40% of all screen-detected cancers.

All screening even the one that causes more harm than good (like neuroblastoma screening) improves both cure rate and 5-year survival simply because of overdiagnosis and lead-time bias. A good example of screening that failed is neuroblastoma screening in Japan. This experiment failed to reduce mortality, but because this program resulted in huge overdiagnosis (the incidence of the early desease more than doubled) the survival rate looked much better. It is very easy to cure a cancer that wasn't going to spread anyway.

This is a simple math: (cured+overdiagnosed)/(detected+overdiagnosed) is always greater than cured/detected given that all of these are positive and the number of cured cases is less than detected. Since cure rate and 5-year survival rates look better even in the absense of benefit, they are not reliable in this case.

The reason 5-year survival rates are misleading is the lead-time bias: if you advance the time of diagnosis, the time between the diagnosis and death will increase even if there is no mortality benefit i.e. two men died at 60 from prostate cancer, in one the desease was diagnosed at 53, in the other at 57. 5-year survival number are only useful if you start from the same point - e.g. if you compare if your drug works better than placebo.

This is why using mortality per number of people has long been the only valid measure of screening success in randomized trials. Not survival, not lead-time. While population data is less reliable than the data from an RCT, it is still more reliable than cured/detected ratio.

David said...

There's a very good overview of prostate cancer statistics at this Google Answers link:

Prostate Cancer Survivability