Confidential details belonging to the East Midlands Ambulance Service have gone missing.
Information including names, addresses and dates of birth were on a data cartridge covering patients from September to November 2012 who were treated by paramedics.
The data cartridge was confirmed missing from the NHS Trust’s headquarters in Nottingham last week.
It contains details taken by ambulance crews from an estimated 42,000 medical emergencies.
Chief executive of the East Midlands Ambulance Service, Sue Noyes, said the incident has been reported to Nottinghamshire Police and the Information Commissioner.
She added that she thinks the disk had been locked away and there had been no break-in at the headquarters.
Ms Noyes said: “We take our responsibility for the security and confidentiality of the information we record and store very seriously and express sincere apologies for a patient data loss incident which we have reported.”
East Midlands Ambulance Service are conducting their own investigation led by an external expert.
There is a possibility that the cartridge is lost on the premises because of its small size and Ms Noyes said that a thorough search of the building is being conducted.
It is unlikely the the information stored on the cartridge can be read by anyone outside the organisation. The data can only be read by specific hardware which is no longer in production.
Ms Noyes said: “It is extremely unfortunate that this incident has occurred, particularly as during this financial year when East Midlands Ambulance Service is replacing the current computerised storage system to strengthen security arrangements.”
People who received an ambulance response between the dates and who had their details recorded in handwriting on a paper Patient Report Form can voice their concerns via telephone on 01158845055.
This line ran by East Midlands Ambulance Service is open from 8am to 8pm.
Ms Noyes added: “We have taken a proactive approach to report this because we are an open and transparent service and we know it is our duty to inform people when such an incident occurs.”