Table 3.

Surgeon and hospital related variables to be included in the planned study

Variable	Dataset	How will data be presented	Method of measurement
Funding	NJR	Categorical: NHS/Independent sector	Documented directly using a specified list on MDS collection form
Grade of primary surgeon	NJR	Categorical: Consultant/Other	Documented directly using a specified list on MDS collection form
Surgeon volume	NJR	Number of TERs performed by a surgeon per year by surgeons	Derived from pseudonymised codes representing the surgeon in charge of patient care. It represents the number of TERs performed from 1st of January to the 31st of December of each year
Hospital volume	NJR	Number of TERs performed by a hospital per year by surgeons	Derived from pseudonymised codes representing the hospital where TER was performed It represents the number of TERs performed from 1st of January to the 31st of December of each year
Regional volume	NJR	Number of TERs per year by surgeons by region	Derived from the hospital where TER was performed. It represents the number of TERs performed from 1st of January to the 31st of December of each year
Duration of elective wait	HES	Number of days waiting	Derived from the date which it was decided to admit the patient and actual admission date
Post-operative duration of stay	HES	Number of inpatient days following surgery	Derived from the date of surgery and date of discharge
Elective admission type	HES	Categorical: General admission/Day case admission	Documented in patient medical records