Non-standard linkage service

The non-standard linkage service is currently suspended due to COVID-19 related pressures.

As of March 2021 we are not accepting any new applications. The service should resume in 2022/23. Existing applications will continue to be progressed, as set out below.

All users of CPRD data must be approved as a CPRD client. To gain approval the new client request form must be submitted prior to starting the non-standard linkage process.

CPRD has a number of standard linkages with other datasets and the full list of currently available linked data can be found on the CPRD linked data web page.  

If a dataset is not already linked to CPRD primary care data as standard, CPRD can be commissioned to undertake a non-standard linkage. although the non-standard linkage service is currently suspended due to COVID-19 related pressures. The service should resume in 2022/23. Upon service resumption, researchers wishing to use the CPRD non-standard linkage service should submit a completed Non-Standard Linkage Service Application Form after reading the associated guidance. If they have any questions about completing the form they should contact


The application form below is for reference only as we are not accepting new applications. 

(PDF, 174 KB, 5 pages)

(October 2020) (PDF, 233KB, 9 pages)

Data-flow diagram templates (DFD) 

Applicants can contact to request a CPRD model data flow diagram template created in Visio. 

What is the process for requesting a non-standard linkage?

The process for obtaining a non-standard linkage is outlined below with some indicative timings and costs which will vary depending on the details of the specific linkage. Overall costs will depend on CPRD time for the linkage process, standard CPRD charges for data extraction and provision, and pass through costs from third-parties, for example the NHS Digital DARS application fee.  

Prices exclude VAT.

Stage 1A: Initial assessment - 1 month

Applicants need to read the Non-Standard Linkage Service (NSLS) Application Form Guidance and complete and submit the following to   

  • The Non-Standard Linkage Service (NSLS) Application Form with any required supporting evidence, e.g. a data flow diagram 

CPRD will conduct an initial assessment of the NSLS Application Form within one month, and inform the Applicant whether: 

  • The application form can be passed forward for to stage 1B for a detailed assessment.  

Cost: Free 

Stage 1B: Detailed assessment - 2 months 

CPRD will review the NSLS Application form to establish whether the linkage is viable based on a number of factors (i.e. potential ethical concerns, legal and technical feasibility, timescale, determining which approvals are required, etc.) and will then inform the Applicant whether the proposed linkage can be taken forward to the next stage and likely costs. 

If the Applicant confirms that they wish to progress to Stage 2, a contract with CPRD will need to be signed.  

Cost: £1,500 

Stage 2: RDG, CAG, additional approvals including DARS applications

Example 1: Individual patient-level linkage based on patient-level identifiers - 13 months 

CPRD will work with the applicant to: 

  • Prepare, issue and sign a contract for the linkage process 
  • Review information governance-related aspects of an RDG application prior to submission  
  • Apply for any other required approvals (e.g. HRA CAG or ODR), in collaboration with any other data controllers. 
  • If required open and complete an NHS Digital Data Access Request Service (DARS) application, in collaboration with the applicant and any other data controllers. 

- CPRD will submit the DARS application to NHS Digital only once all other approvals are in place (e.g. RDG, HRA CAG etc). 
- The NHS Digital DARS team will pre-review the DARS application and once this pre-review is complete, will present the application to the NHS Digital Independent Group Advising on the Release of Data (IGARD).  
- IGARD approval may require several resubmissions. CPRD will undertake one resubmission to IGARD as standard, further resubmissions may incur an additional service charges depending on the work needed.  

Once all approvals are in place, CPRD will: 

  • Prepare a Data Sharing Agreement (DSA) with any third-party data controllers. 
  • Prepare a Dataset Agreement with the applicant

Indicative cost: £10,500

Example 2: Non-standard linkage based on GP practice postcode (including release of the linked dataset) - 6 months 

The process will be as above but potentially requiring fewer approvals (i.e. potentially excluding HRA CAG and the NHS Digital Data Access Request Service (DARS) application) but including the data linkage and release process.

Indicative cost: £6,800














Stage 3: Data linkage and data release - 2 months 

Depending on Data Flows agreed between the applicant, any third-party data controllers and CPRD, the linkage will be undertaken by either NHS Digital or CPRD. For most non-standard linkages this process involves: 

  • NHS Digital producing a bridging file to enable linkage of pseudonymised/de-identified datasets and sends this to CPRD 
  • Any third-party data controllers provide CPRD with study relevant patient IDs and variables 
  • CPRD then creates new linked dataset using the bridging file, CPRD data and the third-party data controllers provided data.  This includes re-pseudonymising all IDs to a study specific ID. 

CPRD, on behalf of the third-party data controllers, manages data releases to the applicant i.e. signing of the Dataset Agreement and secure transfer.

Cost: £9,300 

Total indicative times and CPRD linkage service costs for the examples given above

Example 1: Individual patient-level linkage based on patient-level identifiers 

Total time: 18 months

Total cost: £21,300

Example 2: Non-standard linkage based on GP practice postcode 

Total time: 9 months 

Total cost: £8,300

Conditions for a non-standard linkage with CPRD

  • The applicant must provide all information requested on the Non-Standard Linkage Service application form and provide requested information to CPRD in a timely manner.   
  • Non-standard linkages must follow standard CPRD Data Flows which, for patient level linkages must use the CPRD preferred trusted third party (currently, NHS Digital) to carry out linkages on CPRD’s behalf. 
  • For all non-standard linkages CPRD will create and release the final study dataset which will include study specific pseudonymised identifiers only.   
  • Currently, individual patient-level linkages can only be carried out for health and standard health-related datasets. 
  • The applicant must have provided formal approval in principle for the linkage from all third-party data controllers required for the linkage.   
    - While CPRD does not require a specific format for this approval it must follow the principles outlined in the Non-Standard Linkage Service Application Form Guidance. 
  • CPRD will undertake the linkage under its own HRA-CAG Section 251 approval and acts as the lead applicant on the NHS Digital DARS application.
  • Applicants will be expected to cover any additional pass-through costs applied by third-party data controllers and NHS Digital.
[Page last reviewed 9 June 2021]