Table 1. Study characteristics.
| Study | Year | Location | Study period | Cancer | Patient (N) | Hospital (N) | Surgeon (N) | Hospital volume (/year) | Surgeon volume (/year) | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | High | Low | High | |||||||||
| Liu (11) | 2015 | Taiwan | 2005–2011 | CR | 61,728 | - | <530 | ≥2,623 | <108 | ≥561 | ||
| Leonard (12) | 2014 | Belgium | 2006–2011 | R | 1,469 | 68 | <11 | ≥11 | ||||
| Kolfschoten (6) | 2014 | Netherlands | 2010 | CR | 8,911 | 89 | <50 | ≥50 | - | - | ||
| Richardson (13) | 2013 | Canada | 2006–2006 | R | 377 | - | 25 | 1-5 | 9-14 | |||
| Hohenberger (14) | 2013 | Germany | 1995–2010 | R | 1,028 | 1 | 24 | - | - | <3 | 7–23 | |
| Mroczkowski (15) | 2011 | Germany | 2000–2004 | C | 31,261 | 345 | <30 | >60 | ||||
| Borowski (16) | 2010 | Northern England | 1998–2002 | CR | 8,219 | 17 | <87 | ≥110 | <26 | >40 | ||
| Yasunaga (17) | 2009 | Japan | 2006–2007 | C | 1,212 | 247 | <10 | ≥40 | 30–99 | ≥200 | ||
| Yasunaga (18) | 2009 | Japan | 2006–2007 | R | 2,285 | 371 | <10 | ≥30 | <50 | ≥500 | ||
| Kressner (7) | 2009 | Sweden | 1995–2003 | R | 10,425 | 91 | <11 | >25 | - | |||
| Boudourakis (19) | 2009 | USA | 1999–2005 | C | 9,567 | - | - | - | <12 | >20 | ||
| Truong (20) | 2008 | USA | 1994–2004 | CR | 8,567 | - | <33 | >56 | - | |||
| Ptok (21) | 2007 | Germany | 2000–2001 | R | 1,557 | - | <10 | ≥20 | - | |||
| Bilingsley (22) | 2007 | USA | 1992–1996 | C | 22,672 | 661 | 2677 | <59 | >150 | <10 | ≥27 | |
| Ho (23) | 2006 | USA | 1988–2000 | CR* | C: 175,205; R: 58,568 | |||||||
| Matthiessen (24) | 2006 | Sweden | 1987–1995 | R | 6,833 | NA | NA | |||||
| Rogers (8) | 2006 | USA | 1996–1999 | CR | 28,644 | NA | NA | <84 | >219 | <13 | >40 | |
| Renzulli (25) | 2006 | Switzerland | CR | 915 | <27 | ≥27 | <6 | ≥6 | ||||
| Wibe (26) | 2005 | Norway | 1993–1999 | R | 3,388 | 54 | NA | <10 | ≥30 | |||
| McGrath (27) | 2005 | Australia | 2000–2011 | CR | 1,911 | |||||||
| Kuhry (28) | 2005 | Western Europe | 1997–2003 | C | 536 | 29 | NA | |||||
| Harling (5) | 2005 | Denmark | 1994–1999 | R | 5,021 | 50 | NA | <15 | >30 | |||
| Engel (29) | 2005 | Germany | 1996–1998 | R | 884 | 39 | NA | <10 | >30 | |||
| Urbach (30) | 2004 | Canada | 1994–1999 | CR | 18,898 | 134 | NA | |||||
| Meyerhardt (31) | 2004 | 1990–1992 | R | 1,330 | 646 | NA | ||||||
| McArdle & Hole (32) | 2004 | UK | 1991–1992 | CR | 3,200 | |||||||
| Zingmond (33) | 2003 | USA | 1996–2000 | CR | 56,621 | 101 | NA | ≤20 | >75 | |||
| Schrag (34) | 2003 | USA | 1991–1996 | C | 24,166 | <10 | 17–27 | |||||
| Meyerhardt (35) | 2003 | USA | 1988–1992 | C | 3,759 | <47 | ≥85 | |||||
| Hodgson (36) | 2003 | USA | 1994–1997 | R | 7,257 | <7 | >20 | |||||
| Schrag (37) | 2002 | USA | 1992–1996 | R | 2,815 | 420 | 1,141 | 5 yrs: <6 | 5 yrs: 21–57 | 5 yrs: 1 | 5 yrs: 6–26 | |
| Callahan (38) | 2003 | USA | 1998–2001 | C | 48,582 | 223 | 2,651 | <192 | ≥552 | <28 | ≥79 | |
| Finlayson (4) | 2003 | US | 1995–1997 | C | 120,270 | 1,082 | NA | <61 | >116 | |||
| Martling (39) | 2002 | Sweden | 1995–1997 | R | 652 | NA | 46 | <12 | ≥12 | |||
| Ko (40) | 2002 | USA | 1996 | C | 22,408 | |||||||
| Hannan (41) | 2002 | USA | 1994–1997 | C | 22,128 | 229 | 2,052 | <84 | 254–619 | <12 | 35–262 | |
| Birkmeyer (42) | 2002 | US | 1994–1999 | C | 304,285 | 4,587 | NA | <33 | >124 | |||
| Marusch (43) | 2001 | Germany | 1999 | R | 1,463 | 75 | <20 | >40 | ||||
| Simunovic (44) | 2000 | Canada | 1990 | C | 1,072 | 124 | NA | |||||
| Parry (45) | 1999 | USA | 1993 | CR | C: 548; R: 379 | ≤30 | ≥56 | <7 | ≥19 | |||
| Harmon (46) | 1999 | USA | 1992–1996 | CR | 9,739 | 50 | 812 | <40 | ≥70 | ≤5 | >10 | |
| Khuri (47) | 1999 | USA | 1991–1993 | C | 13,310 | 125 | NA | |||||
| Gordon (48) | 1999 | USA | 1989–1997 | C | 1,015 | NA | NA | |||||
| Kee (49) | 1999 | Belfast | 1990–1994 | CR | 3,135 | |||||||
| Porter (50) | 1998 | Canada | 1983–1990 | R | 683 | 5 | 52 | <21 | ≥21 | |||
| Simons (51) | 1997 | USA | 1988–1992 | R | 2,006 | NA | NA | <5 | ≥5 | |||
| Holm (52) | 1997 | Sweden | NR | R | 1,399 | 14 | 169 | ≤5 | >10 | <4 | ≥4 | |
*, Reported outcomes separately for colon and rectal surgeries. C, colon; R, rectum; CR, colorectal; N, number.