All CPRD datasets contain coded data. The CPRD supply the necessary coding dictionaries and or links to dictionaries to develop code sets and understand the variables used. The key coding schemes and dictionaries used in the NHS are ICD-10, READ, OPCS4, SNOMED CT and the British National Formulary (BNF). In the near future, the CPRD will include ATC drug coding and MedDRA for adverse event reporting in clinical trials.
Primary care observational data will come from all three main general practitioner (GP) Electronic Health Record (EHR)-IT systems. The CPRD data team will ensure that these data are of the highest possible quality by using data quality metrics. This primary care dataset will be maintained as CPRD GOLD.
There will be an incremental approach to increasing the population cover of, particularly, Primary Care data and the introduction of the extended on-line data.
CPRD GOLD will contain patient registration information and all care events that GPs have chosen to record as part of their usual medical practice. Information held will include records of clinical events (medical diagnoses), referrals to specialists and secondary care settings, prescriptions issued in primary care, records of immunisations/vaccinations, diagnostic testing, lifestyle information (e.g. smoking and alcohol status), and all other types of care administered as part of routine GP practice. Data in this online system will be enhanced by the addition of central mortality data (date and causes of death) as well as certain key data from Hospital Episode Statistics (HES- hospitalised patients).
CPRD GOLD will contain the details of all prescriptions – generics and/or branded products issued in primary. Information on formulation, strength and dosing instructions will also be available in both data sources
CPRD has full access to Hospital Episode Statistics (HES) data. HES data will be made available as separate modules of hospitalised care, outpatient visits (visiting a consultant), maternity care and augmented/critical care. In this data source, each patient has a line of data for each "consultant" episode of care; this is best understood as a line of data for each ward in which the patient is treated.
Diagnosis data recorded in HES is based on ICD-10 clinical coding and OPCS4 procedural coding. Health Resource Group (HRG) coding, the currency used in secondary care to support standardised health care commissioning, will also be represented in HES. Access to HRG coded data will enhance the utility of HES data as it will support hospital resource utilisation analyses.