Table ta1.

Office of Population, Censuses and Surveys (OPCS) codes used to identify the heart valve procedures in the study

OPCS code	Description
Heart valve procedures
K25	Plastic repair of mitral valve
K26	Plastic repair of aortic valve
K27	Plastic repair of tricuspid valve
K28	Plastic repair of pulmonary valve
K29	Plastic repair of unspecified valve of heart
K30	Revision of plastic repair of valve of heart
K31	Open incision of valve of heart
K32	Closed incision of valve of heart
K34	Other open operations on valve of heart
K35	Therapeutic transluminal operations on valve of heart
K37	Removal/obstruction from structure adjacent/valve heart
K38	Other operations on structure adjacent to valve of heart