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OPC and Harvey Walsh Limited hosts a secure platform called OPCRD-NEXUS, which securely stores de-identified primary care patient data from OPCRD linked to secondary care patient data, such as Hospital Episode Statistics (HES) data. The platform provides hospital data for practices in England sourced from NHS Digital.

Young Scientist

Why We Need Linked Patient Data?

In order to carry out thorough research, patient data needs to be analysed across various healthcare settings; from primary care through to secondary care (hospitals) and disease registries. Linking primary care data from GP practices to other health data enables us to provide a fuller picture of patient care records to support vital public health, medical and scientific research, including Covid-19 research. This helps bring about advances in science and patient care.


OPCRD-NEXUS is a secure platform that will hold de-identified primary care (GP) patient data from OPCRD which has been linked to secondary care (hospital) patient data such as Hospital Episode Statistics (HES) data. The secure platform is hosted by Harvey Walsh Limited. Hospital data for practices in England is provided by NHS Digital.

De-identified patient data collected from contributing GP practices who have agreed for data linkage is linked to secondary care or hospital data securely, while protecting patient identity and confidentiality. De-identified data is data which has had personal information and sensitive information removed so that you cannot identify any patient. Data is not received for patients who have opted out of sharing their health information for research.

OPCRD has NHS Research Ethics Committee approval to provide anonymised patient data for research including linked hospital data such as HES data and other healthcare data. OPCRD also has HRA Confidential Advisory Group (CAG) Section 251 approval to undertake data HES linkage (REC ref: 20/EM/0148, CAG ref: 21/CAG/0001). CAG Section 251 approval permits confidential patient information to be used without patient consent only for the secure data linkage process. The review and approval process includes a thorough assessment of patient data flows, data security and protection, and patient/public engagement.

OPCRD-NEXUS is jointly managed by Optimum Patient Care Limited (OPC) and Harvey Walsh Limited. OPCRD-NEXUS has been established as part of a scientific and patient-centred collaboration between OPC and Harvey Walsh to improve the provision and/or use of linked primary and secondary care data for research that helps improve patient outcomes including Covid-19.

Optimum Patient Care (OPC)

Optimum Patient Care is a UK social enterprise that has been providing free quality improvement programmes for GP practices since 2005. OPC also supports practices to take part in ethics approved research. OPC maintains and manages the Optimum Patient Care Research Database (OPCRD), which provides de-identified patient data for ethics approved scientific and medical research. OPCRD has NHS Research Ethics Committee approval to provide anonymised patient data for research.

Harvey Walsh

Harvey Walsh Limited is part of the Open Health Group and a leading health research and communications company, with expertise in real world evidence research. Harvey Walsh works in partnership with academic, healthcare and pharmaceutical organisations to undertake real world research that drive improvement in healthcare delivery and science. Harvey Walsh is recognised as a leader in the real world evidence arena for nearly 20 years, supporting over 400 real world evidence projects and facilitating over 200 publications.

Data available in OPCRD-NEXUS

OPCRD holds de-identified data for over 18 million patients in the UK, from over 1000 general practices, and over 66,000 patient questionnaire response data, which have been contributed by GP practices receiving the free OPC quality improvement and research support services. The data includes de-identified patient electronic health records, including structured coded data.

Linkable datasets currently available include:

  • OPCRD longitudinal primary care (GP) data

  • OPCRD patient-reported (questionnaire) data

  • Hospital Episode Statistics Admitted Patient Care

  • Hospital Episode Statistics Accident and Emergency

  • Hospital Episode Statistics Outpatient care

  • Hospital Episode Statistics Critical Care

  • Hospital Episode Statistics Emergency Care Data Set

  • Hospital Episode Statistics Civil Registry Mortality data

OPCRD holds de-identified data for patients in the UK from general practices and patient questionnaire response data, which have been contributed by GP practices in the OPC Network receiving the OPC Quality Improvement and Research Support services. The data includes de-identified patient electronic health records, including structured coded data and redacted free-text data.


Linked data from NHS-Digital includes Hospital Episode Statistics (HES) data from England. It contains information on hospital admissions, accident and emergency attendances, out-patient clinics, as well as civil registry mortality data.

HES OP data are a collection of individual records of outpatient appointments occurring in England only. It includes information on the type of outpatient consultation, appointment dates, the main specialty and treatment specialty under which the patient was treated, referral source, waiting times, clinical diagnosis and procedures performed.

How to access OPCRD-NEXUS

OPCRD-NEXUS linked HES data will be used to conduct data processing and analyses for ethics approved studies, and only the output is provided to the researcher. Researchers will not have direct access to the data held in OPCRD-NEXUS.

All research must be reviewed and approved by the Anonymised Data Ethics and Protocol Transparency Committee (ADEPT) before OPCRD-NEXUS data can be used for the research. ADEPT is responsible for the independent review of proposed research for scientific quality, public benefit, ethical considerations, and any risks posed to patients or data subjects by the research.

Researchers wishing to conduct research using linked data from OPCRD-NEXUS must submit their study or project protocol to ADEPT; with a completed study application form covering details of the intended research. All proposed research must have intent to publish and must have scientific, medical or public health basis. All applications must also include a copy of the Chief or Principal Investigator’s curriculum vitae (no more than 2 pages long).

ADEPT application form, the application process, the approval process, and further information on ADEPT is available here.

After ADEPT approval, the researcher will be required to enter into a strict Data Sharing & Use Agreement and the payment of data processing fees.

Data security and protection

OPCRD-NEXUS is securely hosted by Harvey Walsh Limited, a registered data controller with the Information Commissioner’s Office, registration number: Z9575186. OPC is also a registered data controller with the Information Commissioner’s Office, registration number: ZA197058. OPCRD-NEXUS is protected from unauthorised access, damage or loss, and maintained with industry level security under Harvey Walsh ISO Information Security Standard 27001 Certification.

OPC and Harvey Walsh comply with the NHS Data Security and Protection Toolkit assessment once every year, which is published for transparency across the NHS. The assessment ensures that we comply with the National Data Guardian’s 10 Data Security Standards, including protection of patient confidentiality and respect for patient data rights.

OPCRD-NEXUS does not received any data for patients who have expressed that their data should not be shared, including those who have expressed so through the National Data Opt-out Policy in England.

OPC and Harvey Walsh employees are regularly trained on data protection, including compulsory annual certified training. We conduct regular checks and audits to ensure compliance with the GDPR/Data Protection Act 2018 and our data security policies.

How OPCRD-NEXUS links hospital data

  • OPCRD has Section 251 approval from the Confidentiality Advisory Group for Harvey Walsh and NHS Digital to process patient identifiers from GP practices for the sole purpose of linking OPCRD primary care (GP) data to hospital data.

  • GP practices send a secure file containing only patient identifiers (NHS number, date of birth and sex) to Harvey Walsh, who collect the files from many practices and send it to NHS Digital.

  • NHS Digital conducts a match for the patient identifiers in hospital datasets and then provides only de-identified hospital or HES data for the requested patient identifiers.

  • NHS Digital then send the de-identified hospital data to Harvey Walsh.

  • Harvey Walsh also receives de-identified GP data from OPCRD.

  • Harvey Walsh joins the GP data to hospital data to form the GP-Hospital linked dataset, which is then stored securely in OPCRD-NEXUS.

  • OPCRD-NEXUS never receives any patient-identifiable information from GP practices or from NHS Digital at any stage.

  • OPCRD-NEXUS data is then used to conduct research for studies which have received ethics approval from an independent body called ADEPT – the Anonymised Data Ethics and Protocol Transparency committee.

  • Only outputs (i.e. results or reports) from the research conducted is provided to the researcher. All outputs are fully anonymous and you cannot identify a patient from anonymous data.​

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