Table 3: Summary of literature review of impact of bariatric surgery on Obstructive Sleep Apnoea (OSA).

Study	Study design/sample size	Weight loss procedure	Post-op Follow-up period	Tool to measure sleep apnoea	Pre-procedure		Post-procedure		% sleep apnoea improved/ Resolved Epworth Sleepiness Score
					BMI kg/m^2 (range)	AHI	BMI kg/m^2 (range)	AHI
A Rao, et al. [28]	prospective/n = 75	LAGB^*	12 to 40 months	Sleep study	45.2 (33-60)	38.11 (16.6-137.7)	30 (23-40.3)	13.18 (0.6-91.7)	78% resolved
Charuzi, et al. [29]	Retrospective/n = 47	RYGB^* VBG^*	12 to 84 months	Technion sleep questionnaire, Sleep study	NS^*	60.8 ± 35.5	NS^*	8.0 ± 11.8	72% improved/40% resolved
Poitou, et al. [30]	Prospective/n = 35	RYGB^* Gastric banding	12 months	Sleep study	51.3 ± 1.4	24.5 ± 2.7	39.9 ± 1.3	9.7 ± 1.3	54.3% AHI decrease
Cleator. et al. [31]	Retrospective/n = 20	Ileogastrostomy	11 months	Questionnaire	NS^*	NS^*	42.4	NS^*	30% improved/ 55% resolved/ 15% unchanged
Dixon, et al. [32]	Prospective/n = 25	LAGB^*	17.7 ± 10 months	Sleep study, ESS^*,Neck circumference	52.7 ± 9.5	61.6 ± 31.9	37.2 ± 7.2	13.4 ± 13	ESS^* Pre op 13 ± 7.0 Post op 3.8 ± 3.0
Pillar, et al. [33]	Retrospective/n = 14	RYGB^* VBG^*	4.5 months and 7.5 years	Sleep study	45 ± 7.2	40 ± 29	30 ± 6.0	24 ± 23	72.5% AHI decrease in 4.5 months 40% AHI decrease in 7.5 years
Guardiano, et al. [16]	Retrospective/n = 8	RYGB^*	28 ± 20 months	Sleep study	49 ± 12	55 ± 31	34 ± 12	41 ± 33	75% AHI decrease
Haines, et al. [34]	Prospective/n = 101	RYGB^* (50% open, 50% lap)	11 months (6-42)	Sleep study, ESS^*	56 ± 1	51 ± 4	38 ± 1	15 ± 2	ESS^* Pre op 10 ± 1 Post op 3mo. 6 ± 1 Post op 24mo. 4 ± 1
Cleophas, et al. [22]	Prospective/n = 223	RYGB^* VBG^* Gastric banding	6, 12, 24 months	ESS^*, Short form -12	44.8 ± 7.9	NS^*	28.6 ± 5.5	NS^*	ESS^* Pre op 7.9 ± 4.5 Post op 6mo.5.1 ± 3.2 Post op 12mo.5.3 ± 3.3 Post op 18mo. 5.0 ± 3.4 Post op 24mo. 4.8 ± 3.3
Kalra, et al. [35]	Retrospective/n = 19	RYGB^*	0.9 ± 0.16 years	Sleep study	60.3 ± 2.11	20.5 ± 6.9	NS^*	1.9 ± 0.6
Lankford, et al. [36]	Retrospective/n = 15	RYGB^*	12 months	Sleep study	48 ± 7.4	40 ± 37.2	32 ± 7.8	NS^*	18% reduction in CPAP pressures
Fritscher, et al. [37]	Prospective/n = 12	RYGB^*	24.2 ± 6.4 months	Sleep study, ESS^*	51.55 ± 10.1	46.5 (33-140)	34.1 ± 8.1	16 (0.9-87)	50% improved/25% resolved
Marti-valeri, et al. [38]	Prospective/n = 30	RYGB^*	12 months	Sleep study	56.53 ± 8.39	63.59 ± 38.39	32.12 ± 5.9	17.45 ± 16.64
Lettieri, et al. [24]	Prospective/n = 24	Gastric banding	12 months	Sleep study	51 ± 10.4	47.9 ± 33.8	32.1 ± 5.5	24.5 ± 18.1	4% resolved
Rasheid, et al. [17]	Prospective/n = 11	RYGB^*	3-21 months	Sleep study, ESS^*	62 ± 3	56 ± 13	40 ± 2	23 ± 7	ESS^* Pre op 14 ± 2 Post op 3 ± 1
Scheuller and Wieder, [18]	Retrospective/n = 15	BPD^* VBG^*	12-144 months	Sleep study	NS^*	96.9	NS	11.3	60% resolved
Simard, et al. [39]	Prospective/n = 30	BPD-DS^*	24 months	Questionnaire	56.5 ± 2.3	NS^*	NS^*	NS^*	100% improved
Sugerman, et al. [40]	Retrospective/n = 40	VBG^* RYGB^* HG^*	69.6 ± 28.8 months	Sleep study	58 ± 13	64 ± 39	38 ± 9	26 ± 26
Valencia-Flores, et al. [23]	Retrospective/n = 28	RYGB^* VBG^*	14 months	Sleep study, Neck circumference	56.5 ± 12.3	53.7 ± 46.9	39.2 ± 8.5	13.7	46.6% resolved
Valera, et al. [41]	Prospective/n = 56	RYGB^*	12 months	Sleep study, ESS^*	49 ± 9	35 ± 10	NS^*	NS^*	73% resolved ESS^* Pre op 13.7 ± 5.5 Post op 1 mo. 5.3 ± 4.0

^*LAGB = Laparoscopic Adjustable Gastric Banding, ^*RYGB = Roux-en-Y Gastric Bypass, ^*VBG = Vertical Banded Gastroplasty, ^*BPD-DS = Bilio-Pancreatic Diversion-Duodenal Switch, ^*BPD = Bilio-Pancreatic Diversion, ^*ESS = Epworth Sleepiness Score, ^*HG = Horizontal Gastroplasty, ^*NS = Not Specified