I’ve seen two proposals recently for population screening of older people. They’re probably both not good ideas, but for different reasons.
We had a Stat of the Week nomination for a proposal to screen people over 65 for depression at ordinary GP visits, to prevent suicide. The proposal was based on the fact that 70% of the suicides were in people who had visited a GP within the past month. If the average person over 65 visits a GP less than about 8.5 times a year, this means those visiting their GP are at higher risk. However, the risk is still very small: 225 over 5.5 years is 41/year, 70% of that is 29/year.
To identify those 29, it would be necessary to administer the screening question to a lot of people, at least hundreds of thousands. That in itself is costly; more importantly, since the questionnaire will not be perfectly accurate there will be tens of thousands of positive results. For example, a US randomised trial of depression screening in people over 60 recruited 600 participants from 9000 people screened. In the ‘usual care’ half of the trial there were 3 completed suicides over the next two years; in those receiving more intensive and focused help with depression there were 2. The trial suggests that screening and intensive intervention does help with symptoms of major depression (probably at substantial cost), but it’s not likely to be a feasible intervention to prevent suicide.
The other proposal is from the UK, where GPs will be financially rewarded for dementia diagnoses. In contrast to depression, dementia is pretty much untreatable. There’s nothing that modifies the course of the disease, and even the symptomatic treatments are of very marginal benefit.
The rationale for the proposal is that early diagnosis gives patients and their families more time to think about options and strategies. That could be of some benefit, at least in the subset of people with dementia who are able and willing to talk about it, but similar advance planning could be done — and perhaps better — without waiting for a diagnosis.
Diagnosis isn’t like treatment. As a British GP and blogger, Martin Brunet, points out
We are used to being paid for things of course, like asthma reviews and statin prescribing, and we are well aware of the problems this causes – but at least patients can opt out if they don’t like it.
They can refuse to attend a review, decline our offer of a statin or politely take the pill packet and store it unopened in the kitchen cupboard. They cannot opt out of a diagnosis.