SELF-EMPOWERED, self-motivated, self-aware: we have got used to the idea that more knowledge about our health is good for us. This ethos has fuelled an explosion in wearable technologies – fitness trackers, step counters and other gizmos – that give us real-time feedback on key physiological stats such as heart rate.
, the makers of the bestselling fitness tracker, the Apple Watch, began to roll out a new feature: the ability to monitor heart rhythm, and specifically fibrillation.
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Atrial fibrillation is a relatively common heart condition in which the two atria of the heart – the upper chambers – don’t contract regularly. It can be constant, or intermittent, and becomes more common with age. It increases the risk of blood clots forming and causing a stroke. Those with the condition may need medication to thin their blood and allow their hearts to work efficiently.
So why wouldn’t you want to know if you had it? Certainly, some doctors I have spoken to welcome the diagnostic possibilities that wearables bring; many are enthusiastic users themselves.
The problem is that this is mass screening via the back door, with all the associated positives and negatives. At its best, screening finds diseases at an early stage so that adverse consequences can be avoided. At its worst, it causes far more damage than the disease itself through false positives and unnecessary worry and treatment.
In the UK, the National Health Service follows evidence-based recommendations made by the National Screening Committee. Its current advice is clear: atrial fibrillation. That is because we have evidence that treatment works for people with symptoms, or those found to have the condition while being assessed for another condition. There is no evidence that treatment benefits outweigh the risks for a wider, asymptomatic population.
suggests that 10,000 asymptomatic older people would have to be screened to detect 50 people with atrial fibrillation, and all those 50 would have to be treated to prevent one stroke. Meanwhile preliminary results of one study, funded by Apple, find that diagnoses of atrial fibrillation could be confirmed by a subsequent electrocardiogram of cases.
All this matters because the side effects of the blood thinners used to treat atrial fibrillation can be severe, ranging up to bleeding into the brain or gut. Such treatment would of course only be prescribed after consultation with a doctor. But if you are already finding it difficult to get a doctor’s appointment, think of the impact of a lot of false positives landing on their desk.
In the UK, the SAFER ( Fibrillation with ECG to Reduce stroke) study is getting under way to test whether mass screening for atrial fibrillation is useful, with ethics committee oversight and informed consent. In the meantime, if you have symptoms – breathlessness, chest pain – you should see a doctor. If you want to be screened, enter a trial. Just because early detection sounds sensible doesn’t mean it is good for us.
