Patients who fail to keep hospital appointments cost the UK's National Health Service more than £600 million a year, enough to run two medium-size hospitals, data has shown. Between 2007 and 2008, 6.5 million appointments were missed in the UK, with hospitals losing around £100 per patient in revenue. Young men in their early 20s are the worst offenders and people aged 70 to 74 are the most conscientious about keeping an appointment, the figures show.