The 2003-04 financial year was the first year that Hospital Episode Statistics (HES) collected data on records detailing outpatient appointments delivered by NHS hospitals in England or performed in the independent sector and commissioned by the English NHS. This data was originally released on an 'experimental basis'.
The outpatients' data set contains individual records for all outpatient appointments occurring in England including details such as the type of attendance ie whether it was a first or follow up attendance or the main specialty ie the specialty under which the consultant with prime responsibility for the patient is registered.