Don’t worry about a thing

I got this through the post this morning:

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A flyer on screening for cardiovascular disease, where you can turn up and have scans done for “peace of mind” and all that bollocks.

I’ve no idea where they got my name from or why they think a 28 year old is at significant risk of stroke (must be all that cocaine use…)

It got me in a bit of a rage. These things do.

They use unproven, emotional driven language to make money out of people’s anxiety. Surely the fact that they “can see inside your arteries” impresses you?

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Yes it is true that being over 55 increases you risk of stroke – as does obesity, smoking and lack of exercise. But wait they’re all entirely modifiable risk factors, something you don’t have to pay 140 pound for the privilege of.

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My favourite bit of that photo is the fact that i don’t have to remove my clothes. Phew…

These tests are not accurate. Let me emphasise that. All tests have limitations. Some more significant than others. Lots of these tests find false positives. In other words they tell you have the disease when you don’t. When you screen a population with no symptoms (which is what screening does) then by nature you screen a population with a very low prevalence of the disease you are looking for. If you screen the whole population for pneumonia with a chest x-ray only a very small number will have the disease. If you only take a chest x-ray on people with symptoms of pneumonia then you will pick up far more.

When you screen asymptomatic patients then often the number of false positives outweighs the people actually found to have disease.

Which is why screening in the NHS is so controversial.

Some are now well-established – like breast screening for ladies of a certain age and cervical cancer screening for presumed sexually active women (incidentally they presume everyone is sexually active and therefore screen all women over 18, they just don’t phrase it that way).

Screening for prostate cancer has been less successful – all the men complained that just because they don’t have cervices and boobs that they shouldn’t be left out…

The problem with the PSA test for prostate cancer is that it leads to far too many false positives – it leads people to have prostate biopsies that confirm either no cancer or such low-grade cancer that it’s not actually going to be significant (ie you often die with prostate cancer, not because of prostate cancer).

Ask all the people who get false positive PSA tests if it gave them peace of mind.

Tests are not benign things – one trial (and i can’t find the damn reference) looked at the use of x-rays to assess low back pain. People were randomised (ie both groups were the same) to receive either x-ray or nothing. Those who received the x-ray had worse symptoms at 6 weeks. And of course the x-ray revealed nothing useful to help them. Simply by doing the x-ray these patients were worse.

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That is a plain old fib. Most tests are only worth ordering if you have symptoms but there are other tests that are often ordered in populations at risk – for example the screening programmes already mentioned or simple blood pressure measurement.

The goal to identify patients with significant disease before a problem occurs is very noble (even though their real goal is of course to make money) but unfortunately not possible with what they offer. Every now and again a patient or two will benefit – but over all people will not benefit and some even come to harm.

This one was my favourite – it’s not entirely clear if the Will had carotid dopplers done or not but at least they’re happy together…

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And just to finish: Read this if you’re interested and see what you think about peace of mind for the people found to have aneurysms in their brain.

Vernooij, M.W., et al, N Engl J Med 357(18):1821, November 1, 2007

BACKGROUND: Increasing use of MRI of the brain in clinical practice may be associated with increased detection of incidental cerebral findings of uncertain clinical significance.

METHODS: This Dutch study reports on incidental findings on high-resolution noncontrast- enhanced MRI studies of the brain performed in 2000 asymptomatic subjects aged 45-97 (mean, 63.3 years) (52.4% female) participating in a population-based cohort study.

RESULTS: Incidental findings were common, and most often included asymptomatic cerebral infarcts (7.2%), aneurysms (1.8%), and benign primary tumors (1.6%). The most urgent finding was a large chronic but asymptomatic subdural hematoma in a patient with a history of minor head trauma one month prior to participation. A possibly malignant primary tumor was identified in one subject and cerebral metastases in another. Of the 35 aneurysms, 33 were located in the anterior circulation and 32 were smaller than 7mm in diameter (believed to have a low likelihood of rupture). Operative intervention was considered to be indicated in two patients (the patient with the subdural hematoma and a patient with a 12mm aneurysm). Increasing age was associated with an increasing incidence of asymptomatic cerebral infarcts and meningiomas, and a greater median volume of white matter lesions, but not an increasing prevalence of cerebral aneurysms.

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3 Responses to “Don’t worry about a thing”


  1. 1 theofficeinthestoreroom November 7, 2009 at 2:54 am

    Up there with Homeopathy!!

  2. 2 FF November 7, 2009 at 10:36 am

    I am SO with you on this. Particularly re: PSA testing, both with the rate of false positives, and, as you say the fact that the ‘positives’ are most often not be life threatening or even life affecting. All recent studies re: PSA screening both here and in the States say ‘no’ but I wonder how long it will be before we have to cave to public expectation. FYI there’s a regional PSA audit underway at the moment. The one local disappointment is the delay on bowel screening for NI to later in 2010. It’s a much more useful tool for detection and actually would save lives, and may positively impact some of the worried well bouncing straight up to secondary care at the first sign of symptoms. (We recently carried out an audit on LGI referrals too).

    I think my inner geek has just been released. I’m putting her away now šŸ™‚

  3. 3 Nelly And I November 9, 2009 at 12:39 pm

    i know very little about bowel screening i must say – are they planning colonoscopies or less invasive stuff? Tell you what i’ll just go and look it up…

    the inner geek is always welcome here – i thought that’s what blogs were all about!


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