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DH reviews dementia prevalence estimates after study suggests drop in cases

The Government is reviewing new evidence that suggests a reduction in the prevalence of dementia, in a move that casts doubt over its flagship policy to drive up diagnosis rates.

The Department of Health said it was aiming to gain a consensus view on new evidence that suggests the true prevalence of dementia in the UK may be much lower than previously thought ‘to determine if the current estimates need to be revised’.

The recent Medical Research Council study put the prevalence of dementia at around 670,000 people, or 6.5% of the population, lower than the projected estimate of 800,000.

The results fuelled controversy over the Prime Minister’s Challenge on Dementia, a national programme in England to substantially increase dementia diagnosis rates from the current estimated rate of below 50%.

GPs have been tasked with opportunistically screening at-risk patients under a new DES in England, but critics say that the newer MRC prevalence estimates cast further doubt on the need to increase diagnosis rates and warned the policy is likely to result in considerable numbers of people being wrongly diagnosed.

Writing in the BMJ, dementia tsar Professor Alistair Burns said they were looking at the MRC study as well as recent European data: ‘The Cognitive Function and Ageing Study (CFAS II) and European ALCOVE project have suggested the prevalence may be lower than previously thought. NHS England and the Department of Health are working with academic and clinical colleagues, together with the Alzheimer’s Society and Alzheimer’s Research UK, employing the same Delphi technique as previously used, to establish a consensus as to whether the figure should be amended.’

Professor Steve Iliffe, professor of primary care for old people at University College London and associate director of the UK Dementias and Neurodegenerative Diseases Research Network, said the adjustment of the estimated prevalence could ‘make a big difference’ as some practices may already be diagnosing four-fifths of patients with dementia.

He told Pulse: ‘The adjustment of prevalence figures for dementia syndrome seems likely to reduce the apparent gap between predicted numbers of people with dementia and those registered on QOF. This could make a big difference.

‘If a practice is currently recording 60% of expected numbers on the QOF register, a reduction in predicted prevalence by 25% (which is one of the CFAS suggestions) would mean the practice knows 80% of its dementia patients.’

Professor Iliffe said this would be a ‘substantial achievement’ as there are a number of reasons why diagnosis may be delayed, including patients themselves being resistant to investigations and GPs’ concerns that diagnosis could even worsen the patient’s care, by blocking access to rehabilitation or preventing them going into a care home.

He said: ‘Given the multiple reasons why recognition of dementia may be delayed… this would be a substantial achievement.  All this illustrates the disadvantage of setting targets when the baseline information is inaccurate or flawed.’

A Department of Health spokesperson said: ‘The dementia diagnosis rate is calculated using the current agreed prevalence estimates.  The Department is working with NHS England to examine the new prevalence studies to determine if the current estimates need to be revised.’

A spokesperson from NHS England said: ‘We are aware that recent studies have suggested the prevalence of diagnosis of dementia may be less than the current estimate. This might therefore in the future be amended. We are working with colleagues to consider next steps.’

Rebecca Wood, chief executive of Alzheimer’s Research UK, said that they supported the move to a consensus on prevalence rates.

She said: ‘To get the clearest picture of dementia prevalence, it’s important to look at all the best available evidence and for this reason, Alzheimer’s Research UK is in full support of a Delphi technique to arrive at a reasonable and consensus view.’

The story has been modified to correct the groups being screened for dementia under the DES specification.


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