Care.data is expected to be rolled out sometime in March, and already leaflets are dropping through the doors of every household in England explaining why this is considered so important and attempting to reassure patients that their confidentiality will be protected.

The aim is to join up patient records – GP and hospital data linked to improve care.  The leaflet says “sharing information about the care you have received helps us understand the health needs of everyone and the quality of the treatment and care provided”.

It goes on:  “It also helps researchers by supporting studies that identify patterns in diseases, responses to different treatments, and the effectiveness of different services.”

Dr Clare Gerada, former chair of the Royal College of GPs and now chair of the Board for Transforming Primary Care in London, suggested this morning that if this sort of information had been available, then perhaps the birth defects caused by Thalidomide would have been detected earlier.

And Tim Kelsey, the national director for patients and information at NHS England, said the patient data collected from hospitals had not been compromised once in 25 years.

04 nhsrecords g w NHS must do more to prove that patient data is safe

That may well be true, but data is constantly compromised. We have heard of patient records ending up in skips and NHS-owned laptops being left on trains. In 2008, I reported on the case of  Z,  who had suffered from a rare disease. Her details were held on a confidential data base but still she was contacted by researchers.

Now, this was not a breach of the hospital episode statistics. As we have been told, the HES have never been breached. Nevertheless,  it was a breach.

Mr Kelsey also tried to explain the different levels of confidentiality that will be in place:  green (anonymised), red (identifiable) and amber (not identifiable but can be re-identified).  This last one – amber – has, in fact, seen the introduction into the NHS lexicon of a new word: pseudonymised.

It is all deeply confusing and complex, which is problematic for NHS England, coming as it does at a time the public is increasingly sceptical about governments’ abilities to keep data safe and secure and for it not to be used for other than the intended purposes.

While the stated intentions for this data are irreproachable, NHS England does not seem to be doing a very good job in persuading patients that it is safe in their hands.

Indeed, in NHS England’s plans for the use of this data, it extended those who could apply to use it to “research bodies, information intermediaries, companies, charities, and others”. This has led to fears that it will be used, for instance, by insurance companies.

Again, NHS England is at pains to reassure anyone, when asked, that any organisation applying to use the data has to prove it is for the improvement of patient care and that the pseudonymised data would be exempt.

But the row also continues because of concerns over how well patients understand that they do have the right to opt out of the data sharing, that they can stop their GP from allowing it to be shared.

Mr Kelsey, again, explained on the Today programme this morning “that maybe we haven’t been clear enough”. Actually, it is in the patient leaflet coming through our doors any day now. You can, it says, tell your practice to make a note of this in your medical record.

This does rely on the patient leaflet not being lost in the pile of junk mail, but there are also meant to be notices up in GP surgeries, and GPs are being encouraged to explain the system to anyone who wants to know.

Some have suggested changing the opt-out to opt-in – the patient actively stating that they are happy for their data to go on to care.data. I can only assume it is too late for that now and it is more than likely this would see a significantly lower uptake than the current system.

The final problem for NHS England, however, might be the GPs themselves. A recent survey by Pulse magazine of nearly 400 GPs found that four out of 10 (41 per cent) say they plan to withhold their own records. Forty-three per cent said they would not opt out and 16 per cent were undecided.

Follow @VSMacdonald on Twitter