Impact of being overweight on the surgical outcomes of patients with gastric cancer: A meta-analysis

Table 1 Basic data of included studies

Study	Country	Inclusion period	Sample size	Study type	Follow up period	Percentage of T1 (normal weight vs overweight)	Percentage of N0 (normal weight vs overweight)	Percentage of stage 1/2 (normal weight vs overweight)	Percentage of differentiated (normal weight vs overweight)	Type of gastrectomy	Node dissection	Laparoscopic	Chemotherapy/radiotherapy	BMI cutoff point	Risk of internal control	Risk of confounding factors	Risk of slective report	Risk of variables definition
Gretschel et al[27]	Germany	1992-2001	199	Retrospective	-	15.8% vs 31.6%	26.8% vs 45.3%	Not stated	Not stated	Total	D2	Not stated	Not stated	25, 30	Low	High	High	High
Yamada et al[17]	Japan	1999-2005	248	Retrospective	8-118 mo	53.2% vs 78.3%	Not stated	89.9% vs 93.3%	Not stated	Distal	D2	141 LADG	Not stated	25	Low	Low	Low	Low
Oh et al[29]	South Korea	2009-2009	61	Prospective	-	Not stated	Not stated	Not stated	Not stated	Total	D2	Not stated	Not stated	25	Low	High	Low	Low
Nobuoka et al[40]	Japan	1992-2008	644	Retrospective	-	Not stated	Not stated	53.8% vs 56.6%	Not stated	Total	D2	Not stated	Chemotherapy for advanced cancer and recurrence	25	Low	High	Low	Low
Tsujinaka et al[32]	Japan	1995-2001	523	Prospective	-	0.0% vs 0.0%	Not stated	Not stated	Not stated	Not stated	D2; D3	No	Not stated	25	Low	Low	Low	Low
Ohno et al[37]	Japan	2004-2009	197	Retrospective	-	73.9% vs 77.5%	Not stated	87.2% vs 95.0%	57.3% vs 57.5%	LADG; ODG	D1a; D1b; D2	120 LADG	Not stated	25	Low	Low	Low	High
Pacelli et al[33]	Italy	2000-2006	145	Retrospective	-	Not stated	Not stated	Not stated	Not stated	Distal; total	D2 + D3	No	No preoperative chemotherapy	18.5, 25, 30	Low	High	Low	Low
Yoshikawa et al[39]	Japan	2007-2009	66	Retrospective	-	Not stated	Not stated	92.4% vs 100.0%	Not stated	LADG; LATGc	D1ab + D2	56 LADG; 10 LATG	Not stated	25	Low	Low	Low	High
Murphy et al[35]	United Kingdom	1997-2002	50	Prospective	-	Not stated	Not stated	29.6% vs 65.2%	Not stated	Not stated	D2	No	No preoperative chemotherapy	20, 25, 30	Low	Low	Low	Low
Yasuda et al[34]	Japan	1994-2002	99	Retrospective	48 mo	100.0% vs 100.0%	93.8% vs 95.2%	Not stated	80.7% vs 87.5%	LADG	D1	LADG	Not stated	25	Low	Low	Low	High
Lee et al[38]	South Korea	-2005	1485	Retrospective	At least 3 mo	Not stated	Not stated	89.1% vs 89.0%	Not stated	LADG	D1a; D1b	LADG	Not stated	25	Low	High	Low	High
Kulig et al[18]	Poland	1986-1998	1992	Retrospective	104 mo	13.8% vs 10.6%	17.5% vs 15.0%	Not stated	Not stated	Distal; proximal; total	D1; D2; D2+	No	Not stated	25	Low	High	Low	High
Kim et al[30]	South Korea	2005-2010	1100	Prospective	-	Not stated	Not stated	Not stated	Not stated	LADG	D2	LADG	Not stated	25, 30	Low	High	Low	High
Inagawa et al[28]	Japan	1990-1997	293	Retrospective	10-104 mo	Not stated	Not stated	88.7% vs 94.0%	Not stated	Distal	D2	-	Not stated	20, 25	Low	Low	Low	High
Kawamura et al[36]	Japan	2003-2008	473	Retrospective	-	Not stated	Not stated	100.0% vs 100.0%	Not stated	Distal	Regional	249 LADG	Not stated	25	Low	Low	Low	High
Ojima et al[31]	Japan	1992-2002	689	Retrospective	At least 60 mo	55.3% vs 51.7%	66.1% vs 65.5%	Not stated	53.4% vs 56.9%	Distal; proximal; total	D1; D2; D2+	-	No preoperative chemotherapy	25	Low	High	Low	Low
Tokunaga et al[15]	Japan	1970-2004	7925	Retrospective	At least 60 mo	51.0% vs 60.0%	61.0% vs 68.0%	75.0% vs 83.0%	45.0% vs 40.0%	Distal; proximal; total	Not stated	-	Not stated	25	Low	High	High	Low
Oh et al[16]	South Korea	2000-2003	410	Retrospective	50 mo	15.7% vs 20.9%	41.8% vs 40.4%	47.6% vs 46.5%	32.5% vs 35.4%	Total	D2	-	Not stated	25	Low	Low	Low	Low
Tanaka et al[26]	Japan	2001-2007	191	Retrospective	-	Not stated	Not stated	Not stated	Not stated	Total	D1; D2	-	Not stated	25	Low	High	Low	High
Kunisaki et al[25]	Japan	2002-2008	152	Retrospective	-	Not stated	Not stated	Not stated	Not stated	LADG	D1a; D1b; D2	LADG	Not stated	25	Low	High	High	High
Lee et al[42]	South Korea	2006-2010	243	Retrospective	-	Not stated	Not stated	100.0% vs 100.0%	Not stated	Distal	Not stated	Not stated	Not stated	25	Low	Low	High	High
Bickenbach et al[43]	United States	1985-2007	1853	Retrospective	35 mo	24.6% vs 29.8%	44.5% vs 48.3%	58.6% vs 65.9%	Not stated	Not stated	D1; D2; D2+	Not stated	Not stated	25	Low	High	Low	Low
Deguchi et al[41]	Japan	1999-2008	1640	Retrospective	-	Not stated	Not stated	Not stated	Not stated	Proximal; total	D0; D1; D2; D2+	Not stated	Not stated	25	Low	High	Low	Low

LADG: Laparoscopic-assited distal gastrectomy; ODG: Opem distal gastrectomy; LATG: Laparoscopic-assited total gastrectomy.

Table 2 Summary statistics of pooled data comparing normal body mass index vs high body mass index for overall patients, patients receiving open gastrectomy and laparoscopic gastrectomy

Outcome variables	Studies	Pooled patients	Pooled RR or MD or HR	95%CI	Test for overall effect		Test for heterogeneity
					Z	P value	I2	P value
Overall patients
Operative time	9	5905	-29.14	-38.08, -20.21	6.39	< 0.00001	70%	0.0008
Retrieved lymph nodes	6	4612	1.69	0.75, 2.62	3.55	0.0004	9%	0.36
Blood loss	5	2096	-194.58	-314.21, -74.95	3.19	0.001	86%	< 0.00001
Morbidity	17	17514	0.75	0.66, 0.85	4.48	< 0.00001	58%	0.001
Anastomotic leak	19	12367	0.59	0.42, 0.82	3.07	0.002	34%	0.07
Pancreatic fistula	8	2959	0.46	0.34, 0.63	4.90	< 0.00001	16%	0.3
Mortality	13	16590	0.86	0.58, 1.29	0.71	0.48	0%	0.76
Postoperative hospital stay	6	4552	-5.83	-13.44, 1.78	1.5	0.19	98%	< 0.00001
Cancer-specific survival	5	12321	1.14	1.07, 1.20	4.21	< 0.0001	85%	< 0.0001
Patients receiving open gastrectomy
Operative time	7	2179	-25.24	-33.53, -16.95	5.97	< 0.00001	53%	0.05
Retrieved lymph nodes	6	2838	3.81	-0.34, 7.96	1.8	0.07	91%	< 0.00001
Blood loss	5	1708	-212.93	-301.04, -124.82	4.74	< 0.00001	74%	0.004
Morbidity	11	12510	0.78	0.66, 0.94	2.68	0.007	64%	0.002
Anastomotic leak	14	7320	0.58	0.38, 0.89	2.51	0.01	37%	0.08
Pancreatic fistula	6	2470	0.46	0.38, 0.67	4.03	< 0.0001	37%	0.16
Mortality	10	12763	1.17	0.69, 2.01	0.58	0.56	0%	0.83
Postoperative hospital stay	4	1339	-2.04	-6.00, 1.91	1.01	0.31	80%	0.002
Cancer-specific survival	4	12180	1.14	1.07, 1.20	4.23	< 0.0001	89%	< 0.00001
Patients receiving laparoscopic gastrectomy
Operative time	4	1845	-15.06	-17.41, -12.70	12.52	< 0.00001	0%	0.52
Retrieved lymph nodes	3	1746	2.11	1.35, 2.88	5.39	< 0.00001	0%	0.61
Blood loss	3	360	-47.83	-68.12,-27.53	4.62	< 0.00001	47%	0.15
Morbidity	6	3151	0.48	0.29, 0.79	2.91	0.004	67%	0.009
Anastomotic leak	6	3194	0.83	0.42, 1.65	0.53	0.6	32%	0.2
Pancreatic fistula	3	489	0.3	0.08, 1.20	1.7	0.09	10%	0.33
Mortality	3	1833	0.4	0.12, 1.30	1.53	0.13	0%	0.41
Postoperative hospital stay	3	1833	0.17	-0.80, 1.15	0.35	0.73	34%	0.22
Cancer-specific survival	1	141	1.65	0.13, 20.70	0.39	0.7	Not applicable	Not applicable