Table 1.

Baseline information

Study	Year	Type	Country	Access	Total number of patients	Primary surgery	Quality score according to NOS scale
Topart [29]	2008	CC	France	Lap	259	AGB	7
Cadière [14]	2010	CC	Belgium	Lap	470	AGB, VBG	7
Radtka [23]	2010	CC	USA	Lap/open	928	VBG, RYGB	8
Zingg [31]	2010	CM	Australia	Lap/open	122	AGB, VBG, RYGB, SG	9
Deylgat [19]	2012	CC	Belgium	Lap/open	724	AGB, VBG, SG, RYGB, BPD-DS	8
Slegtenhorst [26]	2012	CC	The Netherlands	Lap/open	292	AGB	8
Stefanidis [1]	2013	CC	USA	ND	1206	AGB	7
Mor [22]	2013	CM	USA	ND	111	MGB, VBG, AGB, RYGB, SG, JIB	8
Thereaux [28]	2014	CC	France	Lap	1008	AGB	7
Thereaux [27]	2014	CM	France	Lap	90	AGB	6
Zhang [30]	2014	CM	USA	Lap/open	344	RYGB, VBG, AGB, SG	7
Delko [18]	2014	CM	Switzerland	Lap	96	AGB	9
Mohos [21]	2014	CM	Hungary	Lap	88	AGB, SG, RYGB, VBG	9
Sadot [25]	2015	CM	Israel	Lap	126	AGB	7
Coblijn, de Raaff [16]	2016	CC	The Netherlands	Lap	1130	ABG, SG	8
Coblijn, Lagarde [17]	2016	CC	The Netherlands	Lap	1667	SG, ABG	7
Raftopoulos [24]	2016	CC	Greece	Lap	820	ND	4
Al-Kurd [12]	2017	CM	Israel	Lap	322	AGB	7
Axer [13]	2017	CM	Sweden	Lap/open	4836	VBG, AGB, GB, SG, GBP, JIB	8
Chowbey [15]	2017	CM	India	Lap	60	SG, AGB	7
Malinka [20]	2017	CM	Switzerland	Lap	64	SG	7

CC case control, CM case matched, AGB laparoscopic adjustable gastric banding, VBG vertical banded gastroplasty surgery, RYGB Roux-en-Y gastric bypass, SG sleeve gastrectomy, BPD-DS biliopancreatic diversion with duodenal switch, MGB mini-gastric bypass, JIB jejunal–jejunal bypass, GB fixed gastric banding, ND no data