Report says data covering in-patient stays between 1997 and 2010 were used to track patients' medical histories

Less than a week after the NHS was forced to postpone its huge GP and hospital record-sharing plan, it has emerged that a major insurance body bought more than a decade's worth of hospital data covering 47 million patients which, it was claimed, is to be used to help insurers refine their premiums.

The Staple Inn Actuarial Society said that data covering all hospital in-patient stays between 1997 and 2010 was used to track patients' medical histories, identified by date of birth and postcode, according to the Daily Telegraph.

The details were then reportedly combined with information from credit ratings agencies and used to advise insurance companies, resulting in increased premiums for most customers below the age of 50.

The newly formed Health & Social Care Information Centre (HSCIC), which collects national health and social care data, said that the records referred to by the Staple Inn Actuarial Society had been provided by a predecessor body, the NHS Information Centre.

It insisted that the records were not used to analyse individual insurance premiums but to analyse general variances in critical illness.

"The newly formed HSCIC can now only provide HES [hospital episode statistics] data to organisations that are looking to improve the way they are run for the benefit of their patients," it said in a statement. "This data is completely protected and does not identify individuals."

The news comes at a time of heightened sensitivity about patient record confidentiality after the postponement of the NHS's massive care.data scheme. The project, which would be the first time that the entire medical history of the nation had been digitised and stored in one place, has been put on hold for six months.

Advocates say that sharing data will make medical advances easier and ultimately save lives because it will allow researchers to investigate drug side effects or the performance of hospital surgical units by tracking the impact on patients.

However, privacy experts warn there will be no way for the public to work out who has their medical records or to what use their data will be put.