The CPRD is run by the Medicines and Healthcare
Products Regulatory Agency (MHRA) and collects anonymised
patient-level data on all medical, prescription,
investigation/test, immunisation and referral records of
registered patients in a sample of GPs in the UK.20 All
practices use a standard software system to submit data to
the CPRD, which has been extensively used and validated
for public health, epidemiological and pharmacoepidemiological
research, as described elsewhere