Why are there several fields for one disease?

At assessment centres, participants answer questions about illnesses they have had before the visit. This self-report data is typically stored in fields 20002 and 20001. However, separate fields can also be provided, such as 2443, which is specific to self-reported diabetes.

UK Biobank receives linked health-related outcome data from the Cancer Registry, Death Registry, NHS Digital (Hospital) and Primary Care providers (GP). This data is also available in various fields, including Field 41270, which contains a Summary of the Hospital Diagnosis records. The underlying Hospital Diagnosis records are available on the UKB-RAP in Entity : hesin_diag and Primary Care diagnosis records can be found in Entity : gp_clinical. UK Biobank has examined data from several of these records and listed the First Occurrence of each illness in fields such as 130709 in Category 1712.  For some diseases, there are also Algorithmically Defined Outcome fields in Category 42, which are detailed in Resource 460.

Additionally, participants answer online questionnaires (such as the chronic pain questionnaire), which includes data about some diseases. For example, questionnaire data about diabetes is located in field 120007. Code Notebooks for exploring the phenotype data are available through the GitHub repository: UK-Biobank/UKB-RAP-Notebooks-Access.