Could Your Smartphone Help Find the UK's "Missing Millions" with High Blood Pressure?

 Sometimes the most interesting conversations start with a simple recommendation.

Recently, Geraint Lewis, Director of Population Health at Microsoft, highlighted an intriguing piece of technology called Lifelight. As someone who spends much of my time thinking about how digital technology can improve health and care, it immediately sparked my curiosity.

Not because it claimed to replace existing medical devices.

But because it raised a much bigger question.

Could the smartphone in your pocket become another tool to help people detect health problems earlier?

The challenge we still face

High blood pressure remains one of the biggest public health challenges in the UK.

An estimated 5 million people are living with undiagnosed hypertension. It's often referred to as the "silent killer"because, for most people, it causes no symptoms until serious complications occur. For many, the first indication is a heart attack, stroke or other cardiovascular event.

Despite the availability of effective treatments, millions simply don't realise they have the condition.

If we are serious about prevention, we need to make checking our health as simple and accessible as possible.

Curiosity became an experiment

Rather than simply reading about the technology, I decided to try it for myself.

I compared the Lifelight app with my own home blood pressure monitor over a number of readings.

The results surprised me.

The app was remarkably consistent.

But it was also consistently higher than my home blood pressure monitor.

That immediately raised the obvious question.

Which one was right?

The honest answer is...

I don't know.

My home blood pressure monitor has never been recalibrated since I bought it. Equally, validated upper-arm blood pressure monitors remain the accepted reference standard for home monitoring.

Rather than jumping to conclusions, it seemed far more sensible to investigate further.

Fortunately, colleagues have access to validated blood pressure monitors at work, so we're planning some simple side-by-side comparisons. This isn't intended to be research or a formal validation study. It's simply an opportunity to better understand how this emerging technology performs against validated reference devices in everyday use.

If nothing else, it should answer two important questions:

• Is my own blood pressure monitor still reading accurately?
• How closely does the app align with validated equipment?

Whatever the outcome, I'll share what we learn.

So how does it work?

The science behind the technology is fascinating.

It doesn't inflate a cuff or measure pressure directly.

Instead, the smartphone camera detects tiny changes in skin colour that occur every time blood flows through the blood vessels in your face. These changes are invisible to the human eye but can be detected using sophisticated image processing.

This technique is known as remote photoplethysmography (rPPG).

Artificial intelligence then analyses the pulse waveform and estimates physiological measurements, including blood pressure.

In other words, it isn't measuring blood pressure directly.

It's using advanced optics, signal processing and machine learning to estimate it.

Whether those estimates are sufficiently accurate for widespread clinical use is exactly the sort of question that needs careful evaluation.

The app has Medical device certification

• EU MDR CE Mark – Class IIa Medical Device for blood pressure and pulse measurement. This means it has undergone conformity assessment under the European Medical Devices Regulation for its intended medical purpose, rather than being marketed solely as a wellness app. 

UK regulatory status

• Lifelight states it is also a Class IIa Medical Device under the UK MDR, allowing it to be marketed for its intended use in the UK. 

The bigger opportunity

For me, this isn't really a story about one app.

It's about the future of prevention.

If technologies like this continue to demonstrate sufficient accuracy and clinical value, should they remain standalone applications?

Or should capabilities like these eventually become part of the NHS App?

The NHS App is increasingly becoming the digital front door to health and care.

Millions of people already use it to order repeat prescriptions, book appointments, access their records and communicate with NHS services.

But imagine if it also became a gateway to proactive health monitoring.

Imagine opening the NHS App and carrying out a simple health check using nothing more than the smartphone already in your pocket.

Not to diagnose yourself.

Not to replace validated medical devices.

But to identify potential concerns earlier and prompt appropriate follow-up using validated equipment or advice from a healthcare professional.

If even a proportion of the estimated five million people living with undiagnosed hypertension were identified earlier, the impact on prevention could be profound.

Digital transformation isn't about technology

Throughout my career, one lesson has remained remarkably consistent.

Digital transformation is rarely about the technology itself.

It's about solving real problems.

Technology is simply one of the tools we use.

What excites me about innovations like this isn't whether one particular app succeeds.

It's that they encourage us to think differently about how we deliver prevention, empower citizens and make healthcare more accessible.

The NHS has ambitious plans to move from treatment to prevention.

To move care closer to home.

To empower people to take greater control of their own health.

If emerging technologies can safely help us achieve those ambitions, then they deserve to be explored with curiosity, tested with rigour and adopted where the evidence supports them.

I'll let the evidence decide

Over the next few weeks, I'll be comparing the app against validated blood pressure monitors with the help of colleagues.

I'm genuinely interested in what we'll find.

The technology may prove to be highly accurate.

It may demonstrate limitations.

Or the answer may be somewhere in between.

Whatever the outcome, I'll share the results.

Because that's how digital innovation should work.

Not through hype.

Not through scepticism.

But through curiosity, evidence and an unwavering focus on improving outcomes for patients.