CPRD GOLD linked Hospital Episode Statistics Outpatient (HES OP) data are a collection of individual records of outpatient appointments occurring in England. The data 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. HES OP data can be used to support health resource utilisation studies, clarify clinical health care pathways and enable variations in the uptake of services to be evaluated, for example by gender and age.