Intervention(s) and comparator(s)	Participants included in analysis [N]a	Deaths [N (%)]	All adverse events [N (%)]b	Severe/serious adverse events [N (%)]
Angrisani 2007	Laparoscopic Roux‐en‐Y gastric bypass	21c	0 (0)	‐	‐
	Laparoscopic adjustable gastric banding	22c	0 (0)	‐	‐
Aasheim 2009	Laparoscopic Roux‐en‐Y gastric bypass	‐	0 (0)	10 (32.0)	‐
	Laparoscopic biliopancreatic diversion with duodenal switch (LDS)	‐	0 (0)	18 (62.0)	‐
Demerdash 2013	Laparoscopic Roux‐en‐Y gastric bypass	16d	‐	‐	‐
	Laparoscopic adjustable gastric band	18d	‐	‐	‐
Dixon 2008	Laparoscopic gastric banding in addition to the conventional therapy	30e	‐	‐	‐
	Conventional therapy	30e	‐	‐	‐
Dixon 2012	Laparoscopic adjustable gastric banding and lifestyle programme	30e	0 (0)	14 (46.7)	5 (16.7)
	2‐year conventional weight‐loss programme and lifestyle programme	30e	0 (0)	13 (43.3)	5 (16.7)
Hedberg 2012	Open biliopancreatic diversion with duodenal switch	24f	1 (4.2)	‐	‐
	Open Roux‐en‐Y gastric bypass	23f	0 (0)	‐	‐
Himpens 2006	Laparoscopic gastric banding	40f	‐	‐	‐
	Laparascopic isolated sleeve gastrectomy	40f	‐	‐	‐
Ikramuddin 2013	Laparoscopic Roux‐en‐Y gastric bypass + lifestyle programme with medical management	60g	0 (0)	‐	22 (36.7)
	Lifestyle programme with medical management	60g	0 (0)	‐	15 (25)
Karamanakos 2008	Laparoscopic Roux‐en‐Y gastric bypass	30h	0 (0)	‐	‐
	Laparoscopic sleeve gastrectomy	30h	0 (0)	‐	‐
Keidar 2013	Laparoscopic Roux‐en‐Y gastric bypass	22h	0 (0)	‐	‐
	Laparoscopic sleeve gastrectomy	19h	0 (0)	‐	‐
Lee 2011	Simplified laparoscopic mini‐gastric bypass with duodenum exclusion	30e	0 (0)	‐	0 (0)
	Laparoscopic sleeve gastrectomy without duodenum exclusion	30e	0 (0)	‐	0 (0)
Liang 2013	Usual care	36i	0 (0)	‐	0 (0)
	Usual care + exenatide	34j	0 (0)	‐	0 (0)
	Laparoscopic Roux‐en‐Y gastric bypass	31j	0 (0)	‐	0 (0)
Mingrone 2012	Gastric bypass	20h	0 (0)	‐	‐
	Medical therapy	20h	0 (0)	‐	‐
Nguyen 2009	Laparoscopic Roux‐en‐Y gastric bypass	111k	1 (0.9)	50 (45.0)	‐
	Laparoscopic adjustable gastric banding	86k	0 (0)	15 (17.4)	‐
Nogués 2010	Laparascopic Roux‐en‐Y gastric bypass	7e	‐	‐	‐
	Laparoscopic sleeve gastrectomy	8e	‐	‐	‐
O'Brien 2006	Laparoscopic adjustable gastric band	39k	‐	7 (17.9)	‐
	Intensive non‐surgical programme	31k	‐	18 (58.1)	‐
Paluszkiewicz 2012	Open Roux‐en‐Y gastric bypass	‐	0 (0)	‐	‐
	Laparoscopic sleeve gastrectomy	‐	0 (0)	‐	‐
Peterli 2012	Laparoscopic Roux‐en‐Y gastric bypass	110l	1 (0.9)	‐	5 (4.5)
	Laparoscopic sleeve gastrectomy	107l	0 (0)	‐	1 (0.9)
Praveen Raj 2012	Laparoscopic duodenojejunal bypass with sleeve gastrectomy	28e	‐	1 (3.6)	‐
	Laparoscopic Roux‐en‐Y gastric bypass	29e	‐	0 (0)	‐
Schauer 2012	Intensive medical therapy alone	41k	0 (0)	‐	4 (9)
	Intensive medical therapy plus laparoscopic Roux‐en‐Y gastric bypass	50k	0 (0)	‐	11 (22)
	Intensive medical therapy plus laparoscopic sleeve gastrectomy	49k	0 (0)	‐	4 (8)
Sharma 2013	Laparoscopic gastric imbrication	12d	0 (0)	‐	‐
	Laparoscopic sleeve gastrectomy	14d	0 (0)	‐	‐
Vix 2013	Laparoscopic Roux‐en‐Y gastric bypass	44d	‐m	‐	‐
	Laparoscopic sleeve gastrectomy	48d	‐m	‐	‐
"‐" denotes not reported aNot all of the studies used the ITT population in the adverse events analyses; footnotes show the population on which each of the analyses were based b'All adverse events' refers to the total number of complications and/or adverse events cStudy completers from 10 year follow‐up dNumber of completers eITT population fThis is the randomised n; unclear if analyses were ITT or not gITT population (missing data included by multiple imputation) hThis is the randomised n iAnalysis population after dropouts (not ITT) ‐ however there were no dropouts in this group jAnalysis population after dropouts (not ITT) kNumber included in the analyses; analyses were not ITT lITT population; analyses based on one year follow‐up data and all participants completed one year follow‐up mNo mortality displayed in CONSORT chart but unclear if mortality occurred among those lost to follow‐up CONSORT: consolidated standards of reporting trials; ITT: intention to treat