Misleading data has emerged as a possible explanation for claims that hospitals discharge large numbers of patients in the middle of the night.

The Times last month reported that 3.5 per cent of all hospital discharges were from 11pm-6am, with some organisations showing significantly higher rates. The data, obtained from 100 trusts under the Freedom of Information Act, led to concerns for patient welfare.

The government asked trusts to examine their performance on the issue. After investigations, some hospitals said many of the times given for patients leaving actually referred to times when data was inputted.

Barnet and Chase Farm Hospitals Trust had 3 per cent of discharges recorded between these hours. Its chief executive Mark Easton told his board: “The time recorded is usually the time the patient’s discharge was put on the system and not the actual time of discharge, meaning that the majority of the figures relate to discharges taking place earlier in the day.”

Mr Easton said a review of complaints about discharge found none relating to night-time discharges.

Derby Hospitals Foundation Trust put its true figure for patients sent home at night at 2.5 per cent, not the 8.7 per cent listed, after finding the same problem with the data. The original figure “inappropriately included patients who had died, patients not admitted to a hospital bed, transfers from one part of the hospital to another, transfers to other hospitals for emergency clinical reasons and patient choice self-discharge”, a spokeswoman said.