The NHS has admitted that "greater scrutiny" should have been applied after it was revealed that the Institute and Faculty of Actuaries paid for medical records to produce a report on pricing .
According to the BBC, details on hospital admissions from 1989 to 2010 were handed to the IFoA, which paid £2220 for the information in Januray 2012.
The information given to the institute contained details on treatments and diagnoses, age, the area the patient lived in, but not their names.
A spokeswoman for the Health and Social Care Information Centre said: "The HSCIC believes greater scrutiny should have been applied by our predecessor body [the centre was known as the NHS Information Centre at the time] prior to an instance where data was shared with an actuarial society.
"We would like to restate that full postcodes and dates of birth were not supplied as part of this data and that it was not used to analyse individual insurance premiums, but to analyse general variances in critical illness."
It said it would publish details of the bodies to whom it supplied such data later this year.
An IFoA statement read: "The IFoA is a not for profit professional body. The research paper - Extending the Critical Path - offered actuaries, working in critical illness pricing, information that would help them to ask the right questions of their own data. The aim of providing context in this way is to help improve the accuracy of pricing. Accurate pricing is considered fairer by many consumers and leads to better reserving by insurance companies.
"Nowhere in this paper does the IFoA recommend a change in insurance pricing."