The Information Commissioner’s Office is concerned that the information provided to patients on is not clear enough about how to opt out of the programme.

Tim Kelsey, NHS England’s director of patients and information, has also admitted that the organisation has “perhaps” not been sufficiently clear about the opt-out.

Speaking on the BBC’s Today Programme this morning, Dawn Monaghan, the ICO’s strategic liaison group manager for public services, said that the organisation is concerned that NHS England has not been explicit enough about the level of data sharing patients can opt-out of.

“We don’t think it is clear enough on the website or in the information that is being sent out exactly what data is going to go and what is not going to go,” she said.

“What it says on the leaflet is that you can object to your personal confidential data leaving the surgery or leaving the (Health and Social Care Information Centre). We’re not sure without further explanation on the website and very clear views, that people will understand what that means.”

NHS England announced a £2m public awareness campaign on last October, after GPs raised concerns about patient consent and confidentiality.

The campaign aims to explain the programme, which will expand the Hospital Episode Statistics and link them to other healthcare data sets, starting with information extracted from GP practices.

As part of the campaign, a leaflet drop to every household in the country was carried out during January. However, privacy campaigners argue that it is easily discarded as junk mail and that the information on how to opt-out of data sharing is insufficient.

Kelsey also appeared on the Today Programme and admitted that the information was “perhaps” lacking a little.

“Perhaps we haven’t been clear enough about the opt-out,” he said.

“Let me be completely clear now: people who don’t trust the NHS to manage their data securely now have a new right as of this scheme. All they need to do is contact their GP to opt out. They will then be opting out of any confidential data leaving the GP practice,” he said.

NHS England has also responded to critics by saying that the leaflets are only part of the overall publicity campaign and that they include web links and a helpline number for patients to get further information.

EHI reported last week that the helpline, which cost £800,000 to set up, has received 3500 calls in its first three weeks, making the average cost of each call around £230.

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