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:

The purpose of this study was to evaluate the effectiveness and safety of the perigastric and pars flaccida pathways for the placement of the Lap-band system. 

Inclusion Criteria:

Inclusion criteria were not directly stated, but the implied criteria included:

  • Body mass index (BMI) that qualified the subjects for bariatric surgery
  • Adult subjects (male and female).
Exclusion Criteria:

Several exclusion criteria were identified:

  • Prior history of bariatric surgery
  • Any surgery in the left upper quadrant that would preclude a Lap-band
  • Need for additional surgeries
  • Unwilling to participate in the study.
Description of Study Protocol:

Design

Prospective randomized controlled trial.

Intervention: Two Surgical Procedures

  • PG pathway (Perigastric surgery): The traditional procedure that involves a dissection between the lesser curvature of the stomach and the lesser omentum, across the apex of the lesser sac, to the angle of His
  • PF pathway (Pars flaccida surgery): A procedure that involves a dissection from the base of the right crus, along the left crus to the angle of His.

Statistical Analysis

Fisher's exact test or the Kruskal-Wallis test for the demographic data to show differences. Continuous data were described using mean ± standard deviations for normally distributed variables or median ± ranges for other variables. For the outcomes data, the groups were compared using a chi-square test (category data) and a student T- test for continuous data.

 

Data Collection Summary:

Timing of Measurements

Follow-up measurements included information from the fifth week post-surgery. Thereafter, measurements were taken in four-week intervals and additional adjustments were performed as determined by weight loss and clinical symptoms. Additional follow-up extended for two years.

Dependent Variables

  • Weight loss [kilogram and percentage excess weight loss (EWL)]
  • Post-surgical complications.

Independent Variables

Type of surgery performed: Perigastric vs. pars flaccida pathways.

Control Variables

All elements of the pre-operative assessment and care, anesthesia, operative technique and post-operative care were identical.

 

Description of Actual Data Sample:
  • Initial N: 202 (23 males, 177 females)
  • Attrition (final N): 98 patients in the PG group and 100 patients in the PF group. Overall loss to follow-up was minimal (2%)
  • Age: Approximately 40 years of age in both groups.

Anthropometrics

Initial BMI:

  • PT group: 44.8+6
  • PF group: 44.6+7.

Location

Australian Centre for Obesity Research and Education, Monash University and The Avenue Hospital in Melbourne, Victoria, Australia.

Summary of Results:

 

 

PG Surgery

PF Surgery

 

Significant Difference

Weight loss at one year

25.3kg±11

 

26.4kg±10

 

None

Percentage EWL at one year

42.4%±16

46.4%±15

None

Weight loss at two years

27kg±13

31kg±4

None

Percentage EWL at two years      46.0%±9    53%+19    None

Surgical Complications

  • In general, all the procedures were a success. About 10% of the patients from the total group required some type of surgical repairs or various forms of surgical intervention for various forms of hernia, cholecystectomies, etc. The operating time was slightly less in the PF group. 
  • Six patients in the PF group patients experienced obstruction at the Lap-band level, which created a delay in being released from the hospital. There was one infection at an access port in a PG patient and one patient in the PG group had to have their band repositioned. 

Late Complications

  • The incidence of prolapse occurred in 19 patients, 15 of these from the PG group (P<0.001). In particular, prolapse of the posterior wall was exclusive to the PG patients. The incidence of anterior prolapse, as well as other complications (erosions, explants, leaks) was not different between the two groups. 

 

Author Conclusion:

The PF pathway is as effective as the PG pathway in generating substantial weight loss and improved health. It is significantly less likely to be associated with slippage or complications from prolapse. 

Funding Source:
University/Hospital: Monash University (Australia)
Reviewer Comments:

This a well-written article. It was easy to understand and I appreciated the fact that the authors had an excellent retention rate. There were very few subjects lost during the follow-up period.

Weight loss achieved: After two years, the patients in this study lost approximately 46% to 53% of their excess weight. Both procedures were successful in achieving the weight loss. 

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? ???
  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? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  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? ???
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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.) No
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  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? N/A
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? No
  10.2. Was the study free from apparent conflict of interest? ???