Table 1. Main characteristics of the eligible studies.
| Study | Year | Country | Recruit period | Study design | Inclusion and exclusion criteria | Consecutive patients | Definition of outcome |
|---|---|---|---|---|---|---|---|
| Asakura [20] | 1997 | Japan | 1984–1993 | Retrospective | Yes | NA | No |
| Lee [21] | 1997 | Korea | 1988–1993 | Retrospective | Yes | NA | No |
| Pfister [22] | 1999 | Canada | 1990–1992 | Retrospective | Yes | NA | No |
| Tomobe [23] | 1999 | Japan | 1989–1994 | Retrospective | No | NA | No |
| Wu [24] | 2000 | Taiwan | 1990–1997 | Retrospective | Yes | NA | No |
| Blanchet [25] | 2001 | France | 1989–1990 | Prospective | No | Yes | Yes |
| Kamai [26] | 2001 | Japan | 1987–1997 | Retrospective | No | Yes | No |
| Kilicli-Camur [27] | 2002 | Turkey | NA | Retrospective | No | NA | Yes |
| Sgambato [28] | 2002 | Italy | 1990–1995 | Retrospective | Yes | Yes | Yes |
| Yan [29] | 2002 | USA | 1994–1999 | Retrospective | Yes | Yes | No |
| Dybowski [30] | 2003 | Poland | 1994–1995 | Retrospective | Yes | NA | No |
| Santos [31] | 2003 | Portugal | 1989–1996 | Retrospective | Yes | Yes | Yes |
| Su [32] | 2003 | Japan | NA | Retrospective | No | NA | Yes |
| Mhawech [33] | 2004 | Switzerland | 1997–2000 | Retrospective | Yes | NA | Yes |
| Krüger [34] | 2005 | Germany | 1987–1999 | Retrospective | Yes | Yes | Yes |
| Theodoropoulos [35] | 2005 | Greece | 1993–2003 | Retrospective | Yes | No | Yes |
| Gonzalez-Campora [36] | 2006 | Spain | 1991–1997 | Retrospective | No | Yes | Yes |
| Quintero [37] | 2006 | Spain | 1990–1994 | Retrospective | No | Yes | Yes |
| Yin [38] | 2006 | China | NA | Retrospective | No | Yes | No |
| Maeng [39] | 2010 | Korea | 2001–2007 | Retrospective | No | NA | No |
| Miyake [40] | 2010 | Japan | 2000–2005 | Retrospective | No | Yes | No |
| Seo [41] | 2010 | Korea | 2001–2007 | Retrospective | Yes | NA | Yes |
| van Rhijn [10] | 2010 | Netherlands | NA | Retrospective | No | NA | Yes |
| Behnsawy [42] | 2011 | Japan | 2000–2007 | Retrospective | No | Yes | No |
| Wosnitzer [43] | 2011 | USA | NA | Retrospective | No | NA | No |
| Acikalin [6] | 2012 | Turkey | 1996–2007 | Retrospective | No | NA | Yes |
| Chen [11] | 2012 | China | NA | Retrospective | No | NA | Yes |
| Ogata [44] | 2012 | Brazil | 2005–2010 | Retrospective | Yes | NA | No |
| Oderda [45] | 2013 | Italy | 1994–2004 | Prospective | No | NA | Yes |
| Okazoe [46] | 2013 | Japan | 2006–2009 | Retrospective | No | NA | No |
| Park [47] | 2013 | Korea | 1990–2007 | Retrospective | No | NA | Yes |
| Ruan [48] | 2013 | China | 2007–2010 | Retrospective | Yes | NA | No |
| Ben Abdelkrim [14] | 2014 | Tunisia | 2001–2003 | Retrospective | No | NA | Yes |
| Bertz [18] | 2014 | Germany | 1989–2006 | Retrospective | No | NA | No |
| Ding [15] | 2014 | China | 2000–2010 | Retrospective | No | NA | Yes |
| Mangrud [49] | 2014 | Norway | 2002–2006 | Retrospective | Yes | Yes | Yes |
| Pan [50] | 2014 | Taiwan | 1991–2005 | Retrospective | No | NA | Yes |
| Özyalvaçli [16] | 2015 | Turkey | 2005–2013 | Retrospective | No | Yes | Yes |
| Poyet [17] | 2015 | Switzerland | 1990–2006 | Retrospective | No | Yes | Yes |
NA: not available.