Do 2 in 5 hospital patients suffer from dementia?

"If you think about the average general hospital now, something like 40 per cent of the patients will have some form of dementia"

Sir David Nicholson in an interview with The Independent, 21 January 2013

Dementia - a syndrome whose symptoms include the deterioration of brain function - is an illness that stalks our homes and our hospital wards.

The Department of Health has estimated that the condition affects around 750,000 people in the UK, most of them elderly (those under 65 years of age account for around one in 40 cases). With this number expected to double in the next 30 years, the NHS is looking into how it might best treat patients who suffer from the disease.

Today the head of the NHS Commissioning Board reiterated the government's commitment to care for elderly patients in the community. Sir David Nicholson observed that hospitals "are very bad places for old, frail people", whose individual needs are often neglected.

And while he did not address this issue directly, Sir David might have added that when the elderly are admitted to hospital there are huge cost implications for the NHS. Crudely speaking, the longer a patient's stay in hospital, the larger the bill. Community care looks like a panacea if we accept that patients suffering from dementia might be better cared for at home or in a health centre and at the same time NHS money might be spent more efficiently. 

However, is Sir David overstating his case when he states that "something like 40 per cent" of the patients in the average general hospital suffer from dementia? There's no source cited, so we'll have to go digging ourselves.

Is it more like 25%?

In 2009 the Alzheimer's Society (Alzheimer's disease being one of the principal causes of dementia) reported that at any one time 25% of hospital beds are occupied by people with dementia.

The charity based this estimate on the fact that in 2001 the Department of Health calculated that those aged 65 and over were responsible for 60% of hospital bed days in the UK. Of this group of over 65s, up to 40% were dementia sufferers. (The 40% figure appears to be based on a focused study of more than 700 elderly patients and how they fared after being admitted for a hip fracture. 40% of this cohort suffered from dementia.)

If we calculate 40% of our 60% of elderly patients, we arrive at an overall figure of around 25%.

Or greater than 25%?

In a 2005 report, the Royal College of Psychiatrists estimated that a typical district general hospital would - on average - find that 31% of its patients over the age of 65 were suffering from dementia. If you were to include patients experiencing depression or delirium, the prevalence of mental illness proved to be much higher, at around 60%.

We do find Sir David's 40% figure in the context of a relatively small-scale study from a London hospital. It looked at more than 600 emergency admissions of those aged over 70 admitted to a London DGH (District General Hospital). In 42% of cases, dementia formed part of the diagnosis. 

Why the variation in these numbers?

Earlier this month, Jeremy Hunt and the Alzheimer's Society jointly decried the fact that dementia is an illness that is far too often ignored. As the NHS Confederation notes:

"A large proportion of people with dementia are undiagnosed and many people go into hospital for a reason not related to their dementia, so the dementia is not coded."

In other words, a patient with dementia who ends up in hospital will often find that their dementia is not officially taken into account ("coded") as part of their diagnosis - even if their condition might have contributed to their hospital admission in the first place. 

It is therefore tricky to estimate the number of patients in an "average" hospital who might be suffering from dementia. It's also important to bear in mind that all the estimates are based on patients over the age of 65 and there will be a small number (around one in 40 of early-onset cases) that affect people below this age.

However, Sir David's estimate of 40% appears to be at the upper end of the scale. We might regard this number as a high watermark, and allow for the fact that the proportion is likely to be up to this threshold, rather than a typical average.