The NHS could save tens of millions of pounds each year by sending text message to patients to remind them of hospital appointments.

Patients who are reminded in this way, or by phone, are 34 per cent less likely to miss an appointment than those who are not, according to a systematic review published in the Journal of Telemedicine and Telecare.

More than 6.5 million outpatient appointments were missed in England last year, at a cost of more than £600m. The worst offenders were patients in their 20s, who accounted for 15 per cent of the total.

Hospital trusts miss out on payments of an average of £100 per missed appointment as they are only paid for patients they see. The review examined 33 studies from countries including the UK, US, Ireland and Australia, and found it cost less than 50p to send a text reminder.

The NHS has struggled with reducing the huge number of missed appointments for years, partly because the system was notoriously inflexible and appointments were booked too far in advance.