Table 2.

Distribution of hospitals and hospital volume among very low and very high volume quintiles for the eight procedures during the study period.

Procedure	Time Period
	2000-2001		2002-2003		2004 - 2005		2006-2007		2008-2009
	Hospital Volume
	Very Low	Very High	Very Low	Very High	Very Low	Very High	Very Low	Very High	Very Low	Very High
Pancreatectomy
Hospitals (N)	1,237		1,119		964		883		926
Hospitals per quintile (N)	866	15	740	14	674	11	639	14	692	14
Annual procedure volume	<2	>17	<2	>22	<3	>28	<3	>30	<5	>41
Colectomy
Hospitals (N)	4,259		4,160		4,181		3,920		3,894
Hospitals per quintile (N)	2,621	177	2,578	174	2,638	170	2,443	164	2,483	155
Annual procedure volume	<22	>82	<23	>88	<22	>84	<22	>80	<29	>109
Esophagectomy
Hospitals (N)	1,559		1,477		1,310		1,216		1,229
Hospitals per quintile (N)	1,023	27	996	26	880	19	816	20	870	19
Annual procedure volume	<2	>12	<2	>12	<2	>17	<2	>17	<3	>18
Coronary Artery Bypass Grafting
Hospitals (N)	1,069		1,107		1,150		1,187		1,189
Hospitals per quintile (N)	569	53	565	57	594	59	606	62	594	69
Annual procedure volume	<127	>480	<113	>422	<93	>325	<72	>257	<79	>272
Aortic Valve Replacement
Hospitals (N)	1,024		1,078		1,112		1,150		1,159
Hospitals per quintile (N)	587	39	621	38	636	41	666	40	674	39
Annual procedure volume	<23	>107	<23	>112	<23	>99	<22	>99	<28	>135
Mitral Valve Replacement
Hospitals (N)	975		1,027		1,049		1,069		1,077
Hospitals per quintile (N)	562	34	599	38	607	36	631	39	610	41
Annual procedure volume	<10	>42	<9	>38	<8	>35	<7	>28	<7	>31
Abdominal Aortic Aneurysm Repair
Hospitals (N)	2,301		2,167		2,050		1,913		1,888
Hospitals per quintile (N)	1,511	64	1,451	59	1,367	60	1,235	61	1,177	69
Annual procedure volume	<14	>73	<16	>78	<16	>72	<16	>70	<18	>77
Carotid Endarterectomy
Hospitals (N)	2,569		2,487		2,444		2,325		2,275
Hospitals per quintile (N)	1,602	96	1,532	101	1,502	102	1,408	100	1,364	103
Annual procedure volume	<32	>141	<32	>134	<28	>112	<26	>100	<29	>108