Table 1.

Volume tertile case ranges, 2009–2010

Tertiles	Case range	Cases	Centres
2009
Low volume centre	11–47	864	38
Medium volume centre	48–75	819	14
High volume centre	>76	942	11
	Totals	2625 cases	63 centres
2010
Low volume centre	13–43	801	34
Medium volume centre	44–70	864	17
High volume centre	>71	840	11
	Totals	2505 cases	62 Centers