Personal health records of more than 38,000 patients have gone missing after a computer back-up tape was lost while being sent by courier to a software company, an NHS trust has confirmed.
Sandown Health Centre on the Isle of Wight sent the tape in March to a London-based specialist software company to carry out checks on its software.
But the password-protected tape, which contained medical records of past and present patient dating back almost 12 years, failed to return to the health centre when it was sent using courier.
In a statement, the Isle of Wight NHS Primary Care Trust said: "It is presumed that the tape has been lost, possibly permanently, although all possible efforts are being made to try and find it."
The statement also said it is considered "best practice" to send back-up tapes to specialist firms, in order to carry out checks.
The specialist company carries out checks on computer back-up tapes to "make sure they could be used effectively to restore information to the practice computer system in the event of a system failure or other emergency such as a fire”.
It is also standard practice to keep information on patients for at least ten years after they are no longer registered with the centre.
Interim chief executive of the PCT, Margaret Pratt, said: "Although there is very little chance of anyone being able to do anything untoward with this tape, should they find it, it is potentially a very serious loss of confidential information."
The NHS Trust assured patients that the risk of the tape being misused is "extremely small" because the tape requires specialist computer equipment to run it and the data is password protected.
The disc is the latest piece of sensitive data to go missing after details about over 25 million child benefit claimants was lost by HM Revenue and Customs (HMRC) in November.
New laws are being proposed to hold Whitehall chiefs personally responsible for data losses within their department.