I am, in general, distinctly sceptical about mass screening programmes. Politicians, however, just love them. They use the complex scientific principle of ‘A stitch in time, save nine.’ Or else the concept of pure logical reasoning known as ‘Better to be safe than sorry.’
On a very superficial level screening is obviously a good thing. You pick up a disease early, then you ‘treat’ it, then it is gone. Huzzah! Pink ribbon anyone? Indeed, how could anyone possibly argue with such an obviously sensible thing to do? So sensible that we are drawn to this idea like moths to a flame. We flutter around it, unable to break free from its mesmerising power.
I am not suggesting that all forms of screening are useless. My favourite screening test is to take someone’s pulse. You can tell within about twenty seconds, or less, if someone has atrial fibrillation (AF). If they do, this is a condition that can be effectively managed, reducing the risk of stroke by nearly a half.
This test costs nothing, requires no great skill, is non-invasive, and…… of course it is not on any screening programme anywhere in the world (as far as I know). Strange, as it fulfils virtually all of the criteria of a successful screening test. As outlined by the WHO as far back as 1968
World Health Organization guidelines on assessing the value of a screening test
- The condition should be an important health problem.
- There should be a treatment for the condition.
- Facilities for diagnosis and treatment should be available.
- There should be a latent stage of the disease.
- There should be a test or examination for the condition.
- The test should be acceptable to the population.
- The natural history of the disease should be adequately understood.
- There should be an agreed policy on whom to treat.
- The total cost of finding a case should be economically balanced in relation to medical expenditure as a whole.
- Case-finding should be a continuous process, not just a “once and for all” project
Instead, we have vastly expensive, poorly sensitive tests for diseases where our treatments are poor, and our knowledge of the natural history of the disease is virtually non-existent. I am not discussing cancer screening here as that is a far more nuanced area.
What I am talking about here, specifically, is dementia screening. Which is the latest bonkers, poorly thought though, damaging bit of stupidity that the UK Govt is now intent forcing on General Practitioners in the UK – and the US. And that was the polite version of my real views.
Here is what the BMJ has to say about dementia screening:
‘Conclusions—Current policy is rolling out untested and uncontrolled experiments in the frailest people in society without a rigorous evaluation of its benefits and harms to individuals, families, service settings, and professionals.’
In fact, the entire article is a paean of common sense, and I would recommend anyone to try and get hold of it, and read it. But journals place themselves behind pay for view barriers nowadays, so you probably can’t.
However on of my favourite passages is the following
‘What will be the effect of encouraging more widespread and earlier diagnosis of dementia? A meta-analysis of the diagnostic accuracy of clinical tools used by general practitioners, including 15 studies on dementia, estimated that if, a clinician saw 100 consecutive community based patients with a prevalence of dementia of 6%, using current criteria he or she would correctly identify four of the six but would incorrectly identify dementia in a further 23 people.’
In short, if there were six out of a hundred patients in the community with early stage dementia. The average clinical would miss two of them, and state that twenty three without the condition had it. My, how fantastically accurate.
A good screening test needs to pick up (or not miss) well over ninety five per-cent of people who have the condition, and not misdiagnose more than one – or two – in a hundred. A misdiagnosis (false positive), is not a trivial thing. ‘I am sorry to tell you Mrs Smith, that you have dementia.’ The effects of being told this can be utterly devastating.
Finances, family planning, the sense of despair that you are going to end up unable to recognise your close family. Dribbling to yourself in a nursing home, doubly incontinent. These are all the things that flash through people’s minds when told they have dementia.
‘But don’t worry, we haven’t got any effective treatment for it either….. you will be glad to know….’ The doctors shall then happily inform the three out of four people that they have MISDIAGNOSED. Whilst thirty per cent of those with dementia wander off happily, reassured that they don’t have dementia – when they have actually got it.
There are times, when I look at the direction of travel in medicine, that I almost give in to despair. There is not enough money to pay for many proven and effective treatments. We are closing hospital beds and making nurses redundant. Our psychiatric services are virtually exterminated due to lack of funding, with severely distressed people unable to access any support.
Yet we can find money – it seems- to fund a completely useless. Sorry, not completely useless. Dementia screening is far more that completely useless – it is actively damaging. We have money to pour into an actively damaging, vastly expensive screening programme to pick up a disease that we cannot actually treat in any meaningful way. Gasp…thud. Noise of head hitting desk.
Luckily, there is always malt whisky to dull the pain.