There is particular concern at the Royal Liverpool Hospital where patients have left the premises to buy drugs or commit other crimes. The hospital is now drawing up a series of contracts, telling patients that they must adhere to the rules. The Bart's and London Hospital is also in the process of drawing up contracts to protect staff from abusive patients and their relatives.
Tony Lee, head of operations at the Royal Liverpool, said: "Patients can be troublesome, abusive, use foul language and not co-operate with their treatments. There is a big problem with them just leaving the hospital without telling staff and for all we know they might be lying in a ditch somewhere."
Mr Lee said the problems centred on a minority of patients who would be asked to sign the contracts on the recommendation of medical staff.
"If they do not comply with their medical treatment then one option could be to discharge them. We are aware of the medical implications of that but we also have a duty of care towards other patients and our staff," said Mr Lee.
A spokeswoman for the Bart's and London said there had been problems with patients and relatives being abusive to staff. "The contracts will explain the behaviour we expect from them and in return the level of care they can expect from us. If we receive a complaint about a patient we will go and see them with the contract and ask them to sign it. Of course if it is a question of the patient's mental health then it's a different issue."