Patients who fail to turn up to their hospital appointments are costing the UK’s National Health Service (NHS) more than £600m each year, the same amount needed to keep two hospitals running, according to new research.

Between 2007 and 2008 NHS patients missed 6.5 million appointments, with hospitals losing around £100 for each missed appointment, the BBC reports.

The UK’s public service trade union Unison said that hospitals scheduling appointments months in advance contribute to patients forgetting about them.

Hospitals are adopting strategies such as text message reminders and allowing patients to choose the time, date and location of their appointment to make treatment more convenient, a Department of Health spokesman said.