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. 2014 Aug 8;2014(8):CD003641. doi: 10.1002/14651858.CD003641.pub4

Summary of findings for the main comparison. Surgery compared with no surgery for obesity.

Surgery compared with no surgery for obesity
Patient or population: participants with obesity
 Settings: any
 Intervention: surgery
 Comparison: no surgery
Outcomes No surgery Surgery Relative effect
 (95% CI) No of participants
 (studies) Quality of the evidence
 (GRADE) Comments
BMI at study end [kg/m²] 
 Follow‐up: 12 to 24 months See comment See comment Not estimablea 582
 (5) ⊕⊕⊕⊝
 moderateb The direction of the effect was consistently in favour of surgery
Health‐related quality of life 
 Short Form Health Survey (SF‐36)
 Follow‐up: mean 2 years See comment See comment Not estimablea 140
 (2) ⊕⊕⊕⊝
 moderatec Improvements were seen in both studies for some aspects of health‐related quality of life but not others
Comobidities: diabetes 
 Different definitions used
 Follow‐up: 12 to 24 months See comment See comment Not estimablea 442
 (5) ⊕⊕⊕⊝
 moderateb More people experienced remission of disease following surgery
Mortality
Follow‐up: 12 to 24 months
See comment See comment Not estimablea 478
(5)
⊕⊕⊕⊝
 moderated 5 of 7 studies reported data: no deaths occurred
Serious adverse events (SAEs) [%]
Follow‐up: 12 to 24 months
See comment See comment Not estimablea 438
(4)
⊕⊝⊝⊝
 very lowe 4 of 7 studies reported data: SAEs ranged from 0% to 37% in the surgery group and from 0% to 25% in the no surgery group
Reoperations [%]
Follow‐up: 12 to 24 months
See comment See comment Not estimablea 470
(5)
⊕⊝⊝⊝
 very lowe 5 studies reported data: 2% to 13% of participants in the surgery group underwent reoperations
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
 BMI: body mass index; CI: confidence interval
GRADE Working Group grades of evidence
 High quality: Further research is very unlikely to change our confidence in the estimate of effect.
 Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
 Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
 Very low quality: We are very uncertain about the estimate.

aStudies could not be pooled due to differences in participants, interventions (types of surgery), and comparators
 bDowngraded by one level because allocation concealment was unclear in most studies. Blinding was not possible in trials of surgery versus no surgery, however this was judged to have little impact on measures of weight/BMI
 cDowngraded by one level because allocation concealment was unclear in one trial. No or unclear blinding of outcome assessors could affect subjective outcomes
 dDowngraded by one level because only 5 of 7 studies provided data
 eDowngraded by three levels because of inconsistent reporting, risk of bias and imprecision