• Increase Font Size
  • Decrease Font Size
  • View as PDF

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:

To determine whether length of the Roux limb influenced weight loss in patients with BMI between 40 and 50kg per m2 and whether length greater than150cm was more effective in those with BMI greater than 50kg per m2.

Inclusion Criteria:

Patients who were candidates for RYGBP in accordance with the recommendations of the National Institutes of Health (NIH).

Exclusion Criteria:

Patients who had undergone a previous weight loss operation and were having a revision to an RYGBP.

Description of Study Protocol:

Recruitment

Patients undergoing RYGBP at the Bariatric Treatment Center of Ohio were recruited to participate.

Design

Prospective randomized clinical trial.

Blinding Used

None.

Intervention

  • Patients underwent standard pre-operative evaluations which included the following:
    • History and physical examination by surgeon
    • Nutritional consultation by licensed dietitian
    • Personality evaluation by a licensed clinical psychologist
    • Routine blood testing
    • Chest X-rays
    • Electrocardiogram
    • Ultrasound of gallbladder.
  • Patients were stratified according to their BMI:
    • BMI greater than or equal to 50kg per m2 
    • BMI less than or equal to 50kg per m2.
  • Patients were randomized to one of the following groups according to alimentary limb lengths:
    • 75cm limb
    • 150cm limb for those with BMI less than 50kg per m2  
    • 150cm limb for those with BMI greater than 50kg per m2  
    • 250cm limb. 
  • RYGBP procedure was performed the same day patients were admitted to hospital. Some of the technical features followed included:
    • Upper midline laparotomy
    • 15 to 30ml gastric pouch using super-imposed staple-lines
    • Limb lengths measured "in situ"
    • Stapled jejuno-jejunostomy.
  • Post-operative diet:
    • Liquids started two days post-operatively
    • Diet was advanced to pureed as tolerated
    • Approximately by day three to four post-operatively, patients were discharged from hospital tolerating a diet.

Statistical Analysis

Descriptive statistics and student T-test or Chi-square to test differences among groups were used.

Data Collection Summary:

Timing of Measurements

Two weeks, three months, six months, 12 months, 18 months, 24 months, three years. 

Dependent Variables

  • Caloric (kcal per day) and protein (g/day) intake using a 24 hour recall administered by licensed dietitian,
  • Body weight (kg) using the same scale
  • Change in BMI
  • Percentage of excess weight loss (%EWL)
  • Percentage of patients with %EWL more than 50% with time; used as a definition of a succesful weight loss surgery. 

 Independent Variables

  • Roux limb length
  • BMI less than or equal to 50kg per m2: 75cm or 150cm
  • BMI geater than 50kg per m2: 150cm or 250cm.
Description of Actual Data Sample:

Initial N

N=133.

Attrition (final N)

  • 128 (106 females, 22 males)
  • Attrition was due to post-operative complications (N=3) and mortality (N=2).

Mean Age

39.7 years.

Ethnicity

Not described.

Other Relevant Demographics

  • Race was reported for each treatment group separately
  • 80-89% of participants in each group were classified as Caucasian.

Anthropometrics

Initial Weight (kg/lb) Across Groups 

Group

Initial Weight (kg / lb)

A

120/264

B

122/268

C

171/376

D

177/389
  • No significant differences reported among groups at baseline although statistical test values were not reported
  • No significant differences reported across groups at baseline for age, gender or race
  • Statistical test values were not reported.

Location

Ohio.

Summary of Results:
  • No difference in absolute weight loss or %EWL according to limb length for patients with pre-operative BMI greater than or equal to 50kg per m2
  • Patients who 250cm Roux limb (pre-operative BMI greater than 50kg per m2) had significantly greater %EWL than those patients with the 150cm Roux limb (P<0.05). 
Months
After Surgery
Approximate %EWL
Across Treatment Groups
6

37-53
12 50-70
18 50-80
24 50-60
36 50-60
 
Other Findings
  • No cases of protein-caloric malnutrition or calcium deficiency were noted. These were not defined in the article.

 

Author Conclusion:
  • In patients with BMI less than 50kg per m2, there appears to be no advantage to longer limb-lengths
  • In patients with BMI greater than 50kg per m2, these data suggest that longer alimentary limb-length may be associated with a higher percent of patients achieving more than 50% EWL.

 

Funding Source:
University/Hospital: Ohio State University School of Medicine
Reviewer Comments:
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? No
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes