A laptop containing the medical records of more than 5,000 patients has been stolen from a hospital, it was revealed today.
The computer was taken from the outpatients department at Russells Hall Hospital in Dudley, West Midlands, on January 8.
It contains a database with information on 5,123 anticoagulation patients, the hospital said.
Letters have been sent to those affected and police have launched an investigation.
Paul Farenden, chief executive of Dudley Group of Hospitals NHS Trust, said the laptop was taken from an anticoagulation clinic, which treats people who suffer from blood-thinning problems.
He said a username and password was required to operate the computer, and a separate username and password was needed for the database.
He said there was no evidence to suggest that the patient information had been accessed.
Mr Farenden went on: "Clearly this is a serious issue. We take precautions to try to protect all the IT equipment in our hospitals from theft but, given that this is a public building with thousands of people accessing it every day, there are inevitably practical difficulties around security.
"Our security team works very hard to ensure the safety of our staff, patients and visitors, but it is very difficult to mitigate against all deliberate acts of theft.
"We would like to apologise for any concern this matter has caused those patients affected, and would like to reassure them that the information on the database is unlikely to be recoverable."
A police spokeswoman said: "West Midlands Police is investigating the theft of a laptop computer from Russells Hall Hospital on January 8, 2008.
"The Fujitsu Siemens Lifebook laptop was taken from an office in the outpatient department some time between 2.15pm and 4.15pm.
"Anyone with information about the incident is urged to call Dudley police station on 0845 113 5000."