Table 2. Surgeon and hospital characteristics.

Variable	Surgeon caseload					Hospital caseload
	High-volume(22–96)		Medium-volume(9–21)	Low-volume(1–8)	Pvalue	High-volume(86–244)	Medium-volume(40–76)	Low-volume(1–39)	Pvalue
Total no. of surgeons/hospitals	12		30	154		3	8	26
Age, years
Mean ±SD	47±7		41±6	41±8	0.047
Range	36–59		31–56	30–75
Gender					0.372
Male	12		30	147
Female	0		0	7
Urbanization of hospital location					0.148				0.090
Urban	8		12	50		2	4	5
Suburban	3		16	83		0	4	18
Rural	1		2	21		1	0	3
Geographic region of hospital location					0.777				0.713
Northern	5		13	81		1	4	13
Central	3		5	23		0	2	5
Southern/Eastern		4	12	50		2	2	8
Caseload (Mean ±SD)	38±20		14±4	3±2	<0.001	145±86	57±13	16±14	<0.001

SD, standard deviation.