EAL

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 pilot study was to determine the morbidity and mortality that resulted from banded and unbanded laparoscopic Roux-en-Y gastric bypass surgery.

Inclusion Criteria:

Morbidly obese
Body mass index (BMI) of 40 to 55kg per m²
Agreement to participate in the study with written consent
Deemed to be psychologically ready to have the surgery
Cooperative regarding nutritional counseling assessments.

Exclusion Criteria:

Not meeting the BMI criteria
Failure to meet the psychological criteria established pre-surgery.

Description of Study Protocol:

Recruitment: Morbidly obese patients whocame to the Department of Surgery, Mexico City, Mexico
Design: Pilot randomized controlled, clinical trial
Blinding used: Sealed envelopes opened just before surgical procedure
Intervention: Banded laparoscopic Roux-en-Y gastric bypass surgery vs. unbanded laparoscopic Roux-en-Y gastric bypass surgery
Statistical analysis: Means ± standard deviations, comparative frequencies and percent excess weight loss (% EWL).

Data Collection Summary:

Timing of measurements: Pre-operative, six, 12, and 24 months of follow-up
Dependent variables: Complications of surgery, changes in BMI and excess body weight loss
Independent variable: Surgical procedure, either banded or unbanded Roux-en-Y gastric bypass.

Description of Actual Data Sample:

Initial N: 60 (7 males, 53 females)
Attrition (final N): Study is ongoing
Average Age:
- Unbanded group: 36.5±9.7 years
- Banded group: 37.8±9.6 years.
Ethnicity: Hispanic
Anthropometrics: Groups were similar on all important measures
- The average mean pre-operative body weight was 125±17kg in the unbanded group and 126.8±17kg in the banded group
- The mean pre-operative BMI was 47±5kg per m² in the unbanded group and 48±5kg per m² in the banded group
- The BMI range was 40 to 55kg per m².
Location: Mexico City, Mexico, Department of Surgery.

Summary of Results:

The operative time, hospital stay and complication rate were very similar in both groups. Over the course of time, the vomiting frequency decreased in both groups. Vomiting was a slightly greater concern among the patients who had the banded surgical procedure. One patient in the banded group underwent laparoscopic band removal because of stenosis at the level of band placement.
No statistically significant differences were found in the percent excess weight loss (% EWL) or the BMI between the two groups. Both groups successfully lost about 70% EWL at the two-year interval. The range was as low as 33% EWL and as high as 77% EWL.

Author Conclusion:

The weight loss in both groups was very similar at one- and two-year post-operative measurements
The authors conclude that more follow-up is necessary for patients undergoing gastric bypass surgery.

Funding Source:

University/Hospital:

Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán

Reviewer Comments:

This article had an excellent discussion section. The authors clearly explain the physiological mechanisms involved in weight loss after RYGB surgery. They also clearly explain the different anatomic changes that occur post-surgery to produce a tolerance for larger amounts of food.
There was limited information about the subjects, their recruitment strategies, the health of the subjects or their demographic information other than gender, age and BMI.

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?		???
	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?	No
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	No
	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.)	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?		No
	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%.)	???
	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?	N/A
	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?	N/A
	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)?	???
	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?	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?	Yes