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Dementia DES will result in widespread misdiagnosis, expert claims

Exclusive: Many patients will be misdiagnosed with dementia as a direct result of the controversial case finding DES, the GP expert who led a campaign against its introduction has warned.

Dr Martin Brunet, a GP in Surrey and programme director for the Guildford GP VTS, said newly published evidence suggests that widespread GP use of dementia screening tools will result in 23 patients being wrongly identified with possible dementia for every four patients correctly identified with the condition.

‘It is very likely that the DES will cause lots of people without dementia to be incorrectly diagnosed with it,’ he said.

‘If you artificially try to push up the rate of dementia diagnosis by giving GPs incentives, there is a very real danger that you will misdiagnose people with very bad consequences.’

Citing a paper published this week in the BMJ that looked at the accuracy of dementia screening tools used by GPs, Dr Brunet told the Pulse Mental Health Forum in London: ‘If GPs assess 100 people for dementia – and the true prevalence is assumed to be 6% –they will correctly diagnose four of those six people. But they would also incorrectly identify dementia in 23 more people who don’t have it.’

Under the new DES, all 27 patients picked up by the GP assessment would be referred to memory clinics. Speaking after the event, Dr Brunet said: ‘You would expect the memory clinic to correctly identify the four cases of dementia. But will some of the other 23 people end up with a dementia diagnosis when they don’t have it? However good memory clinics are, you would think so.’

He added: ‘Others will end up with a diagnosis of mild cognitive impairment – is that helpful to the patient? Probably not.’

His claim was refuted by the Government’s national dementia tsar, Professor Alistair Burns, who told the event NHS England is determined to increase the proportion of dementia cases that get diagnosed from the current 46% to at least two-thirds.

But Dr Brunet said the 46% figure was ‘just a guesstimate’ based on very old data whereas the most recent evidence suggested dementia rates were declining, in part because of the reduction in smoking rates. A recent Lancet paper found a ‘substantial’ decline in dementia over the past two decades, with an actual rate of 6.5% of the population, compared with an expected level of 8%. Dr Brunet added: ‘We should be very proactive if someone – or a family member – comes in saying they are worried about their memory. But we need to trust patients, relatives and GPs to know when to start that process.’

Dr Brunet was a member of a group that launched a petition against the controversial DES, that sees GPs assess all over-75s and all over-60s in risk groups for dementia, and who met with the dementia tsar earlier this year to discuss alternatives.

Dr Chris Fox, clinical senior lecturer in old age psychiatry at the University of East Anglia, said he shared Dr Brunet’s concerns. ‘I would like to accentuate the harms – I’m aware of NHS litigation cases based on misdiagnosis of dementia.’

Dr Lindsay Hadley, a GP and mental health adviser to Hastings and Rother CCG who has set up a primary care memory clinic, said the DES raised possible issues around consent. ‘One of the problems of doing it opportunistically is you don’t achieve consent.

‘Someone comes for a diabetes appointment and you say “I’m just going to check your memory”. What they don’t understand in that small interchange is the implication of a positive test.’

But Professor Sube Banerjee, professor of dementia at Brighton and Sussex medical school and author of the National Dementia Strategy, said: ‘Should we not diagnose because some people will be misdiagnosed? Dementia is an appalling and devastating illness and delaying diagnosis by two, four, seven years causes real harm.

‘What about the curse of not knowing, of not understanding what’s going on, of the system not being able to provide support?’

Dementia tsar Professor Burns added: ‘The idea of a “curse” of diagnosis doesn’t fit well with my experience with patients and carers. A diagnosis begins to open doors to be able to access support.’



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