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The unfathomable dementia calculator

The dementia prevalence calculator is beyond a joke.

Ever since my practice was given an initial diagnosis rate of 127%, I have questioned the scientific validity of trying to estimate diagnosis rates for an individual practice.

But the wild swings in diagnosis rate my practice has been given over the last five years has led me to wonder if the whole thing is powered by a random number generator.

If I was in any doubt about the validity of the calculator, my practice figures for March have delivered the final blow: our register of patients with dementia has fallen from 98 to 96, while our so called diagnosis rate has plummeted from 78% to 52%.

In fact, the statistics from our practice have shown how ludicrous these figures have been since the start. The 127% figure has mysteriously disappeared from the website, but even so the graph is pretty bizarre.

How is it that diagnosing 101 patients with dementia gave us a 64% rate in 2010, but an 80% rate in Nov 2014?

Why did our diagnosis rate jump up so much between September and November 2014, while the actual number of patients fell?

Why did we only need 78 patients to achieve a 50% diagnosis rate in 2009, while 96 patients this month gives us only 2% more?

One theoretical explanation would be huge changes in our list size, but that hasn’t happened.

I suspect the real reason is that NHS England keeps changing the goalposts. It just can’t decide how many patients with dementia we should have, and keeps changing its estimates. Minor tweaks as they refine their maths I could tolerate, but they have had five years to get this right. For GPs to still be subject to a 25% swing is totally unacceptable.

When NHS England announced that it was to change the way it calculates these figures, it also said that they were ‘solely for use by NHS England in holding CCGs to account’, so why is practice level data published at all? And when it is so unreliable, why do we put up with it? Which other organisation would accept such incompetent external measurement of their performance?

NHS England has nearly achieved its aggressive drive to achieve a diagnosis rate of 67% – through the controversial DES the numbers have increased by nearly 70,000 in the last six months.

No doubt those behind the scheme will be congratulating themselves, while ignoring the fact that the quality of many of these ‘new diagnoses’ must be questioned – many will be the result of a simple paper exercise with read codes changed on records but no impact on patient care, others may be a tentative diagnosis to be confirmed or refuted at a later date, but coded as dementia in the meantime.

Now we must be firm and say ‘enough is enough’. Let’s get back to diagnosing people just because that’s good old-fashioned doctoring. Let’s stop the publication of flawed practice-level data that will be misunderstood and misinterpreted at every level, and let’s focus, at last, on the real challenge: improving the care for all those affected by dementia.

Dr Martin Brunet is a GP in Guildford and programme director of the Guildford GPVTS. You can tweet him @DocMartin68.