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Shielded Patient List: Data quality

NHS Digital uses a range of clinical datasets to produce the Shielded Patient List each week.


Extracts from GP systems capture GP revisions to a patient’s risk status, additions and deductions of patients from the high-risk group submitted by NHS trusts, and strategic data collections. These include data from hospital episodes, maternity health data and medicines data, to determine whether a patient meets one or more of the nationally agreed criteria as set out by the Chief Medical Officer.

The data processed constitutes hundreds of millions of data items.

These national datasets are being used to support direct care during the COVID-19 pandemic. However, some issues with data quality have been noted when identifying and communicating with clinically extremely vulnerable patients through the NHS Shielded Patient List programme.

These include:

Residential addresses - When people move home, they do not always update their records with their GP, including when patients may temporarily or permanently move into or out of a care provider or care home.

Email addresses - NHS Digital gathers email addresses held on GP and other health systems. We do not verify the accuracy of patient contact information, which is managed by GPs and hospital departments on behalf of patients.

Telephone numbers - The telephone numbers used for national communications are taken from the contact information held in a patient’s GP record, so it is important to make sure this is up to date.

Improving data quality

The currency and accuracy of the data NHS Digital collects from and on behalf of the health and care system is important to the Shielded Patient List.

We use the national Personal Demographics Service (PDS) which is the national electronic database of NHS patient details, alongside the Master Person Service which is used to further validate patient information when identifying clinically extremely vulnerable patients.

Patient demographic data is used by a number of national and local patient systems and we are working to improve the data quality and provide ways for patients to maintain their own contact details.

To improve demographic data, we are:

  • taking steps to improve the data quality of incorrect email addresses on patient records
  • developing tools to enable the removal of data reported as incorrect from the patient record at a national level and working with primary care suppliers to review and revise local GP systems - this includes email and telephone numbers and information reported as incorrect by patients
  • reviewing the overall strategic approach to the currency and accuracy of demographic data collected and managed by NHS Digital

Last edited: 24 August 2021 12:23 pm