Personal demographic service (PDS)

Version 1.2, 24 February 2023

This guidance is part of the Patient record and information systems’ functionality section of the Good practice guidelines for GP electronic patient records.

What is PDS?

The Personal Demographics Service (PDS) is the national electronic database of NHS patient demographic data, such as name, address, date of birth and NHS number.

The database contains a central record of the demographics for each person registered for, or in receipt of, health and care services comissioned by NHS organisations in England, Wales, the Isle of Man, or UK defence medical services. 

There is also a retrospective view for those who have been in receipt of NHS (primary and secondary) care since 2004, whether they are alive, deceased, living in England, or otherwise no longer engaged with the NHS in England.

Multiple NHS applications connect to the PDS and synchronisation with the PDS allows the most up-to-date details to be held on all systems.  The main purpose of the PDS is to support direct care.

It is General Data Protection Regulation (GDPR) compliant.  A summary of how data is processed can be found here PDS: GDPR information.

How it works

Allocation of numbers

There are a number of ways in which NHS numbers are allocated.

All new patients, by automated process, have an NHS number allocated by Primary Care Support England (PCSE) when they register for general medical services with a GP practice.  To capture the necessary details, patients must complete a new patient registration, ideally in a digital format, or an equivalent paper form.  Once processed for the first time, their PDS record is created.

A new registration form also has to be completed when a patient transfers practices, and in this instance their PDS is updated.

Other ways in which an NHS number may be allocated to a patient are:

  • by maternity services or a child health unit (CHU) following birth
  • by data feed from the Home Office for migrants and visitors who have paid the Immigration Health Surcharge, or who fall into one of the exempt categories, e.g. victims of modern slavery, domestic violence, sex trafficking, asylum seekers
  • those retaining rights under the European Union Settlement Scheme who had not previously interacted with the NHS and therefore did not already hold an NHS number
  • to patients referred for secondary care in England from the home countries or Channel Islands
  • residents of the detained and secure estates, i.e. prisons

The PDS National Back Office (NBO) will allocate NHS numbers by exception, on request from secondary or primary care support, in cases of change of identity or in complex data quality cases.

Checks and validations

When a patient record is retrieved in an electronic health system, a check is made with the PDS to ensure the patient record has the most up-to-date information. In most systems this check is on opening the patient record. In EMIS WEB, however, patient details are checked against PDS when a ‘trigger module’ (care record, registration, and some modules within workflow management) is accessed.  If a discrepancy is found, in any system, the person accessing the record is alerted to the differences and asked to confirm the correct details. The PDS and clinical system are then updated.

The patient’s registered GP practice may need to validate any information amended by other healthcare providers, or updated by the patient themselves. An updated contact number or address added by a hospital will, for example, pop up as a reminder for practice staff to confirm each time the patient record is opened until the difference is resolved. 

GP systems may not, however, hold the most up-to-date information and practices need to be cautious not to make this assumption. Currently the ‘old number/address’ goes into history and the ‘new’ entry becomes the valid one. This stays until it is verified. 

The requirement for validation of email and telephone number changes is currently under review and expected to be removed in the near future.

In some general practice systems staff with access rights are asked to validate a list of all PDS changes made elsewhere or by staff logged in without their smartcard, each time they access the clinical system.  Changes should be authorised regularly (ideally on a daily basis) providing the user accepts the update.  If rejected, it leads to data differences between the systems which ultimately have to be resolved.

Patients who use digital services such as the NHS App, Airmid, etc., can add details to their records such as telephone numbers and email addresses. 

Practices should offer a change of details form electronically through the practice website.


Only authorised health and social care professionals, including authorised administrative staff in a healthcare setting, can access the PDS database to accurately associate patients with their medical record where:

  • they are authorised to use the system and may access via a secure network connection with or without a smartcard
  • they have located the correct patient using their demographics details or NHS number (this may involve identifying the correct patient from a picking list of possible matches)
  • there is a legitimate relationship between the user and the patient, and with the user’s organisation, for example to provide care as an in-patient or out-patient in a secondary care setting

Some users, such as local authority social care services, may also access PDS via the internet using a range of available secure options.  Administrative staff from NHS Digital, Primary Care Support England (PCSE) and the NBO may also access PDS for purposes such as screening.


Online patient facing services (PFS) allow patients to:

  • view their electronic medical record
  • order repeat prescriptions
  • communicate with their GP practice
  • book GP appointments

A patient will need to provide some key information to log in to the provider system for any of the above services, such as date of birth etc.  PDS will verify the details are correct and give access limited to the specific request (rather than access to a patient’s full record).

For a full list of PFS providers please see the website. Some use NHS login.  

Information held

The information held on the PDS database includes:

  • NHS number
  • name
  • gender (note: Back Office staff would give a new NHS number on gender reassignment)
  • birth information
  • address
  • contact details
  • registered GP
  • preferred pharmacy
  • consent information (relating to telephone contact by the e-referral service)
  • related people, such as next of kin
  • death information

Changes to the above are actioned and verified by the registration authority during the lifetime of the patient on receipt of the appropriate documentation.

The PDS does not hold any clinical health record information or other sensitive data items such as ethnicity or religion.

In order to manage patients of no fixed abode or where the address is not known, and the practice does not know where they tend to stay, there are a set of pseudo postcodes (see section 7) to show this.

Homeless patients can be registering using the Practice postcode.

Uses in, and benefits to, primary care

PDS provides the following uses in, and associated benefits to, primary care organisations:

  • registration (and de-registration) with a care provider, whether as a patient at a GP practice or with other service providers
  • cross-checking by authorised care providers for updates regarding a registered patient
  • referring patients via the Electronic Referral Service (e-RS)
  • using the Electronic Prescription Service (EPS)
  • enabling transmission of health records between primary care providers (GP2GP
  • processing of patient applications for, and allowing access to an NHS login account
  • allowing GP appointment booking and ordering repeat medication through the NHS App or other similar applications
  • creation and update of a patient’s Summary Care Record (SCR)
  • checking by authorised care providers of a patient’s chargeable status in the case of visitors or migrants
  • changes to PDS triggers movement of paper medical records
  • ensures individuals are included in national screening programmes such as cancer screening and AAA (abdominal aortic aneurism) screening – the link gives further information on the current screening programmes and their target audiences; for example AAA screening is offered to men during the year they turn 65
  • ensures inclusion in immunisation programmes

Effects of mismatching

In addition to the uses and benefits listed, mismatching can result in:

  • no access to other Spine services such as the SCR, e-RS and EPS
  • recording clinical care in the wrong patient record
  • an individual’s record being mixed up or ‘confused’ with the record of one or more other patients which may cause issues regarding the patient’s details and possible delays in the delivery or transfer of care (known as a ‘confusion’)
  • an inability to refer to urgent care appointments

The clinical implications of mismatching could result in incorrect provision of care or delays in the delivery or transfer of care, including missing invitations to screening.

If multiple patients become combined in one record and the differences cannot be resolved, then the local record is ‘de-coupled’ from the PDS, and no update is made. This will then be sorted out by the NBO process.

Duplicate patients may have multiple incomplete records.

Caution | Where the parents of a child are separated

Caution must be used when updating children’s details in the case of a family breakdown.  

It is best practice in such cases to agree demographic changes with both parents or the person with parental responsibility.  If you feel there is any doubt that the person making the request has parental responsibility for the child, you can ask to see a copy of the child’s birth certificate and/or the parents’ marriage certificate, or a letter from the person’s solicitor confirming their parental responsibility status.  (Remember that it’s possible for parental responsibility to have been removed after the date of these documents). 

Tip | It is worth putting a reminder on a patient’s home screen if there is more than one patient with the same name.

PDS flagged records

The PDS National Back Office is responsible for the management of NHS numbers and PDS records.  NHS patients have no specific legal right to prevent demographic data being stored on the PDS. There are, however, cases where access to a patient’s details must be strictly controlled.

Access to demographic records can be restricted on request by, or on behalf of, any NHS patient who feels that their location details should not be accessible by the NHS.  In these circumstances a flag may be added to a patient record. 

Flags can only be added, amended, or deleted by the PDS NBO.  This level of flagging is retained during a GP2GP transfer.

There are 4 types of flags used:

  • sensitive
  • invalid
  • business (this flag is a legacy and no longer maintained, consideration is being given to the removal of these indicators)
  • data quality

Note | The screenshots below illustrate the general wording of each type of alert.  Your clinical system may look different as the messages apply to local system behaviour, and any actions and options presented may also be different.

Bear in mind that flagged records are very rare.  In most cases the flag is for information only and you will not need to take any action.

Sensitive flags

If a record is flagged as sensitive, details that would reveal the location of the patient, are restricted for viewing. This is to protect vulnerable patients, for example:

  • victims of domestic violence
  • victims of forced marriages
  • family break-ups
  • vulnerable children awaiting adoption (the flag is not set for adoption cases, but it may be requested for children who are on the pathway to adoption or post adoption on specific request – this is likely due to specific vulnerabilities rather than the adoption)
  • law court witnesses
  • patients who are keen to restrict as much data that is held about them as possible, for their own personal reasons/their feeling this is their human right
  • short-term protection pending identity change

Patients are able to request a restriction on their record by completing the access restriction request form, which is processed by the NBO.

Patients should discuss the ramifications of being marked as sensitive with their GP, as restricting access to their record may cause difficulties in some care settings.  It is worth noting that relevant role-based access rights (RBAC) give access to the local record only, in order to manage any location information held within the local GP system, they do not automatically give access to the full PDS record.

Retrieving and accessing a record with a sensitive flag means:

  • the record can be accessed, but only the patient’s NHS number, name, date of birth and gender will be displayed, with other demographic details remaining hidden
  • you will not be able to amend any details for the record on PDS
  • in most cases, the restriction means that the patient will be unable to benefit from any of the national Spine systems that require location information, including e-RS, EPS, GP2GP and Covid pass (this area is currently under review)
  • there may be some cases where the restricted access is overridden, for example for access to national services such as cancer screening, when this will usually be provided through the NBO
  • a practice cannot remove a restriction on a patient’s record, however they may need to deal with a patient asking for restriction to be removed using the access restriction request form

Invalid flags

The invalid flag may be used when an NHS number is being deleted/discontinued. This could be for legal or safeguarding reasons, for example adoption, gender reassignment, other protected person such as witness protection or where there are possible data quality issues that have been dealt with.

In the case of duplicates, records are merged, one number is retained, and the other is superseded.  PDS retains a systemic link between the two and if someone traces a patient using the superseded number, the PDS record for the retained number will be returned. 

Retrieving and accessing a record with an invalid flag means:

  • a discontinued NHS number has been used or a record is no longer in use, (for example where two patient records have been merged and one is no longer used) in which case the NHS number that should be used will be returned
  • the healthcare professional will not be able to see any demographic information for the patient and a message will be displayed indicating the record is not valid and that they should search for the correct demographic record, the searcher gets a ‘No trace’ response

Data quality indicators

A data quality (DQ) indicator shows that the PDS NBO believes there is a possible data quality issue with the record and that an audit check is required.

Retrieving and accessing a record with a DQ indicator means:

  • PDS NBO believes there is a possible data quality issue with the record (for example a duplicate record)
  • the healthcare professional will be able to see the patient’s full demographic details, but they will see a message indicating a possible data quality issue and asking them to verify demographic details when the patient presents to the NHS

Verification of changes

When a practice receives a PDS change notice, verification should always be requested to ensure accurate recording of information.  PDS changes can be initiated from any user organisation, without any validation required.  These changes should not be accepted by the practice that holds the patient record unless the change has been corroborated by the patient or the person accepting the change has seen evidence that the change is either correct, or incorrect. 

Staff who directly deal with PDS changes must be made aware of the importance of accuracy and the potential impact incorrect data could have on patient care.  If staff become aware of a data quality issue on a patient’s record, they should report it for investigation.  If PDS data is not accepted the PDS and local record will be out of sync, this may have implications for the future care of the patient and the accuracy of NHS records.


  • The PDS acts as a ‘master record’ for patients’ demographic details
  • It is the route by which patients can be identified and linked to their medical records held on the NHS Spine
  • It is vital that the data held in PDS is as accurate and current as possible
  • Maintaining PDS information is the responsibility of all who use it but as the GP practice is often the first and most frequent point of contact, it has a particular responsibility to ensure correct information is recorded and changes instigated in other parts of the NHS are accepted

Other helpful resources

Contact Information

Please email the Good Practice Guidelines team here for more information on this subject.