Table 1.

Clinical characteristics of gastric cancer patients undergoing gastrectomy from 30 included studies.

References	Study design	Country	Period	Number of patients	Number of hospitals	Hospital volume (cases/year)	POM (death/total) (%)	Definition of POM
Wirth et al.53	Retrospective	Switzerland	2014–2018	188	62	≤10	1.9	In-hospital
						>10	1.3
Narendra et al.54	Retrospective	Australia	2001–2015	796	49	<5	5.0	30-day
						≥5	3.0
Iwatsuki et al.34	Retrospective	Japan	2011–2015	71 307	2051	0–11	3.1	In-hospital
						12–26	1.7
						27–146	1.2
Ji et al.5	Retrospective	China	2013–2018	125 683	515	1–83	0.44	In-hospital
						84–238	0.29
						239–579	0.24
						580–1193	0.15
Diers et al.35	Retrospective	Germany	2009–2017	46 187	1084	≤10	6.9	In-hospital
						11–29	5.8
						≥30	3.9
Tian et al.8	Retrospective	Australia	2001–2015	1253	49	<5	6.4	In-hospital
						≥5	4.3
Levy et al.56	Retrospective	Canada	2004–2015	1660	69	0–2	6.6	30 days
						2.5–5	NA
						5.5–7.5	NA
						8–11.5	NA
						12–22	3.1
Shibao et al.55	Retrospective	Japan	2012–2013	37 752	1074	1–35	NA	In-hospital
						36–61	NA
						62–97	NA
						98–458	NA
Iwatsuki et al.6	Retrospective	Japan	2011–2015	145 523	2182	1–22	1.9	In-hospital
						23–51	1.0
						52–404	0.5
Wu et al.57	Retrospective	China	2000–2010	7905	185	<10	4.1	30 days
						≥10	1.9
Claassen et al.7	Retrospective	Netherlands	2007–2015	494	NA	1–10	1.6	In-hospital/30 days
						11–20	4.3
						21–30	2.0
						≥31	0.63
Haga et al.36	Retrospective	Japan	2000–2003	2045	NA	≤90	0.84	30 days
						>90	0.07
Ptok et al.58	Prospective	Germany	2007–2009	2897	140	<5	7.8	In-hospital
						5–10	5.5
						11–20	6.6
						>20	5.8
Busweiler et al.61	Retrospective	Netherlands	2007–2015	4837	NA	<15	7.4	30 days
						15–39	6.1
						≥40	4.8
Güller et al.60	Prospective	Switzerland	1999–2012	4404	NA	1–10	4.9	In-hospital
						>10	3.3
Liu et al.59	Retrospective	United States	2010–2013	17 923	1297	≤4	NA	30 days
						>4	NA
Murata et al.62	Retrospective	Japan	2009–2011	5941	741	<40	0.5	In-hospital
						≥40	0.3
Altini et al.37	Retrospective	Italy	2004–2008	1314	16	<7	11.9	In-hospital/30 days
						7–21	NA
						≥21	4.2
Smith et al.63	Retrospective	Australia	2000–2009	1621	84	≤6	5.1	30 days
						>6	3.8
Dikken et al.39	Retrospective	Netherlands,	2004–2009	9010	NA	1–10	4.4	30 days
		England,				11–20	NA
		Sweden,				≥21	6.7
		Denmark,
Ho et al.38	Retrospective	Netherlands	2008–2010	1024	88	1–6	6.1	30 days
						7–9	6.4
						≥10	4.6
Ghaferi et al.9	Retrospective	United States	2005–2007	8838	NA	1–4	17.7	In-hospital/30 days
						NA	NA
						NA	NA
						11–110	7.5
Kim et al.32	Retrospective	South Korea	2002–2005	11 071	NA	<39	0.71	30 days
						39–126	0.86
						>126	0.36
Skipworth et al.40	Retrospective	Scotland	1982–2003	4589	61	1–3	8.9	In-hospital
						4–5	12.0
						6–9	9.4
						≥10	8.6
Baré et al.33	Retrospective	Spain	2001–2002	3241	144	<18	7.9	In-hospital
						18–35	11.7
						>35	11.6
Thompson et al.41	Prospective	Scotland	1997–1999	639	39	<13	11.9	In-hospital/30 days
						13–19	9.1
						20–34	10.3
						≥35	10.0
Lin et al.42	Retrospective	China	2000–2003	11 348	174	Q1	5.4	In-hospital
						Q2	3.4
						Q3	3.1
						Q4	1.6
						Q5	1.4
Wainess et al.64	Retrospective	United States	1988–2000	23,690	NA	1–4	8.3	In-hospital
						5–8	7.1
						≥9	6.5
Damhuis et al.65	Retrospective	Netherlands	1987–1997	1978	22	<7	8.0	30 days
						7–10	9.8
						>10	6.8
Birkmeyer et al.10	Retrospective	United States	1994–1999	31,944	3423	<5	13.0	In-hospital/30 days
						5–8	12.7
						9–13	11.1
						14–21	11.3
						>21	8.7

NA, not available; OR, odds ratio; POM, postoperative mortality; Q, quintiles.