Wearable technology promises to revolutionise health care

I stealthy killer. When the heart’s chambers beat out of sync, blood pools and clots may form. Atrial fibrillation causes a quarter of more than 100,000 strokes in Britain each year. Most of those would never happen if the heart arrhythmia were treated, but first it has to be found. Tests are costly and inaccurate, but Apple Watches, and soon Fitbits, can detect it, are far cheaper and can save those whose lives are in danger.

This is just one example of the revolution about to transform medicine. Smartwatches and -rings, fitness trackers and a rapidly growing array of electronically enhanced straps, patches and other “wearables” can record over 7,500 physiological and behavioural variables. Some of them are more useful than others, obviously, but, as our Technology Quarterly in this issue explains, machine learning can filter a torrent of data to reveal a continuous, quantified picture of you and your health.

These are early days for the quantified self, and for investors in digital health it is still a wild ride. Witness the recent collapse in the share price of Teladoc, which provides online consultations, a worrying sign for other would-be disrupters. But for patients the innovation in wearable devices has just begun. Individual firms may come and go, but wearables and artificial intelligence look set to reshape health care in three big ways: early diagnosis, personalised treatment and the management of chronic disease. Each promises to lower costs and save lives.

Start with early diagnosis. Wearables can detect subtle changes that otherwise go unnoticed, leading to less severe disease and cheaper treatment. Sensors will reveal if an older person’s balance is starting to weaken. People’s gait and arm-swing change in early-stage Parkinson’s. Strength exercise can help prevent falls and broken limbs. Psychiatric diagnosis may be enhanced by tracking patterns of smartphone use—without monitoring what people see or type. A smart ring can help a woman conceive, by predicting her menstrual cycle. It can also detect pregnancy less than a week after conception (many women continue to drink or smoke for weeks before they realise they are pregnant).

Then there is the promise of seeing people as individuals, not clones of the theoretical, average human. Most drugs work in just 30-50% of patients. In one person, regularly eating bananas moderates blood sugar; in another, it raises blood sugar to levels that, over time, can cause harm. Algorithms can turn reams of data from wearables into bespoke prescriptions and diets for losing weight, controlling diabetes and so on. These regimes are more effective, less limiting and hence easier to follow than the one-size-fits-all kind. When doctors can see into a patient’s body in real time all the time, they can provide better care. In a German trial this sort of monitoring of heart-failure patients reduced mortality and the days spent in hospital by a third.

And wearables can transform chronic diseases, such as diabetes. Some 80% of disease can be prevented by changes in how people lead their lives.