NCBS: Weight Loss and Weight Regain Expected After Procedure (2009)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

Bariatric surgery has been proven as an effective short-term obesity treatment option; however, the long-term outcomes of bariatric surgery on weight status and body mass index is less well known. This systematic review examined published reports of outcomes from bariatric surgery from three to ten years of follow-up.

Inclusion Criteria:

 Peer reviewed manuscripts were included if they:

  • Were in English
  • Were a full research report
  • Had at least 100 patients
  • Presented at least three years of follow-up data
  • Used one of the following procedures:
    • Laparoscopic adjustable gastric banding (LAGB)
    • Standard Rouxen-Y gastric bypass (RYGBP)
    • Biliopancreatic diversion (BPD)
    • Hybrid procedures of banded gastric bypass (Banded RYGBP) and long-limb gastric bypass where the Roux limb length was (LL x RYGBP).  
       
Exclusion Criteria:

Abstracts and unpublished data were not included in the review.

Description of Study Protocol:

Recruitment

Articles published on or before September 1, 2005 were identified from:

  • Medline
  • Current Contents
  • Embase
  • ScienceDirect
  • PubMed
  • Cochrane database.

 Search terms included:

  • Laparoscopic adjustable gastric banding
  • LAGB
  • Swedish adjustable gastric banding
  • SAGB
  • Gastric bypass
  • Roux Y gastric bypass
  • Roux-en-Y
  • Roux-en-Y gastric bypass
  • RYGBP
  • GBP
  • Biliopancreatic diversion
  • BPD
  • Duodenal switch
  • Bariatric.

Journals directly relevant to obesity research, such as Obesity Surgery, Obesity Research and International Journal of Obesity and Related Metabolic Disorders were checked electronically or manually.

Design

Systematic review.

Statistical Analysis

"The mean percentage excess weight loss (EWL), number of patients and time of follow-up were recorded from each study. A fixed-effect model was used because of inconsistent reporting of standard deviations. The pooled mean and pooled weighted mean values were calculated for each time point, and pair-wise comparisons of surgical techniques as specific time points were made using the Man Whitney-U non-parametric test.

Data Collection Summary:

Timing of Measurements

Annual follow-up values served as the primary end points.

Dependent Variables

  • Percentage of excess weight loss (EWL): Ideal weight was either defined as ideal body weight or a body mass index (BMI) of 25
  • Change in BMI.

Independent Variables

Annual changes in percentage of EWL and BMI were compared across surgery type [Standard Rouxen-Y gastric bypass (RYGBP), laparoscopic adjustable gastric banding (LAGB) and biliopancreatic diversion (BPD)].

 

Description of Actual Data Sample:

Initial N

  • 1,703 articles were identified based on search terms
  • 43 articles met inclusion and exclusion criteria.

Location

Multiple sites: 

  • 18 articles on LAGB
  • 18 articles on Standard RYGBP
  • Seven articles on BPD.
Summary of Results:

  

Type of Surgery
Years of Follow-up RYGBP LL-RYGBP Banded RYGBP LAGB BPD
  Percentage Excess Weight Loss
1 67.3 53.3 75.4 42* 71.8
2 67.5 58.5 78.8 52.7* 75.1
3 62.5 60.3 76.9 54.8 76.3
4 58   76 54.5 75.5
5 58.2 55.5 74.7 55.2 73.3*
6 53.3   73.4 49.8 74.2
7 55   72.3 51 69
8     71.3 59.3 75.8
9     67.6    
10 52.5   61.5   77

*Significantly different at P<0.05 (comparisons for RYGP, LAGB and BDP by time).

Abbreviations key: RYGBP (Roux-en-Y gastric gypass); LL-RYGBP (Long Limb Roux-en-Y gastric bypass); LAGB (laparoscopic adjustable gastric banding); BPD (biliopancreatic diversion).

 

 

 

 

 

 

 

 

 

 

 

Other Findings

  • Mean percentage EWL were in the range of 54% to 67% with no evidence of loss of effect at 10 years
  • No significant differences were found for BMI by the three surgery types at any point in time. No operation attained a mean BMI less than 30 kg/m2.

 

Author Conclusion:

The authors were surprised by the lack of data available regarding long-term outcomes from surgery. All groups achieved at least 50% EWL, with BPD providing the greatest results.

These data were limited by:

  • The lack of follow-up data that may be biased by failure to follow up based on failure to achieve outcomes
  • Limited number of reports that met inclusion criteria
  • Single outcome nature of the study for percentage EWL or BMI change
  • Limited data on patients, especially at each measurement time.
Funding Source:
University/Hospital: Monash University (Australia)
Reviewer Comments:

These data appear to be an accurate and unbiased representation of the available data regarding the research question.

Quality Criteria Checklist: Review Articles
Relevance Questions
  1. Will the answer if true, have a direct bearing on the health of patients? Yes
  2. Is the outcome or topic something that patients/clients/population groups would care about? Yes
  3. Is the problem addressed in the review one that is relevant to dietetics practice? Yes
  4. Will the information, if true, require a change in practice? Yes
 
Validity Questions
  1. Was the question for the review clearly focused and appropriate? Yes
  2. Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described? Yes
  3. Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased? Yes
  4. Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible? No
  5. Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined? Yes
  6. Was the outcome of interest clearly indicated? Were other potential harms and benefits considered? Yes
  7. Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described? Yes
  8. Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included? Yes
  9. Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed? Yes
  10. Was bias due to the review's funding or sponsorship unlikely? Yes