Table 1.

Procedures included in each group for regression modelling

Procedure group	Procedures included, with OPCS-4 codes
Subtotal/total colectomy	Subtotal colectomy (H29)
	Total colectomy (H05)
	Panproctocolectomy (H04)
Right colectomy	Right hemicolectomy (H07)
	Extended right hemicolectomy (H06)
	Transverse colectomy (H08)
Left colectomy	Left hemicolectomy (H09)
	Sigmoid colectomy (H10)
Rectal resection	Anterior resection (H33·2–33·4, H33·6, H33·8–33·9)
	Abdominoperineal resection (H33·1)
	Hartmann's procedure (H33·5)

OPCS-4, Office of Population Censuses and Surveys Classification of Interventions and Procedures, version 4·4.