Wearable cuffless blood pressure tracking: when will they be good enough?

Wearable health monitoring is a multibillion-dollar industry. But the holy grail is probably getting it right for blood pressure monitoring without a cuff, because raised blood pressure is very common and the leading cause of death in the world. Many have tried and failed, but industry is persisting: numerous cuffless wearable blood pressure devices are on the market, several technologies have been developed, hundreds of patents are registered every year, and some devices already have regulatory approval. However, to convince the die-hard blood pressure critic is a different ball game. To understand the challenges of currently accepted methods and cuffless devices, I performed a 24-h blood pressure monitoring self-test, including measurements when awake, asleep and watching an intense match of the Rugby World Cup final, with the purpose to demonstrate the challenges and opportunities we face. Blood pressure was monitored using five different devices simultaneously: validated left and right arm cuff blood pressure, and three cuffless wearable devices (wrist-band, chest patch and a ring). Whilst none of these devices proved to be perfect in capturing a physiologically challenging measure, namely blood pressure, it emphasised that our current practice of a single blood pressure measurement in clinical practice should be revisited. It further begs the question of when cuffless measurements will be good enough to incorporate in clinical decision-making.