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 the study was to present complete information from several surgical sites in the US, regarding three-years of efficacy data and nine years of follow-up safety data for trial A and one-year safety and efficacy data for trial B.

Inclusion Criteria:

18 to 56 years
Body weight over 100 pounds or over 45kg above ideal body weight (IBW)
Multiple failed attempts to lose weight or maintain the loss using non-surgical strategies
Permission to have the surgery needed to be granted per insurance company or other arrangements had to be made to pay for the surgery
Sign consent form.

Exclusion Criteria:

Exclusion criteria included previous gastric or small-bowel surgery, severe cardiopulmonary disorders or any other medical condition making surgical placement of the device life-threatening.

Description of Study Protocol:

Recruitment: The actual patient recruitment procedure was not described in detail, other than the patients came to the multiple clinics across the US. They were screened, informed and qualified for the procedures.
Design: Prospective, multi-center, open-label single-arm surgical trial of three years (trial A) and prospective, open-label, expanded access study, multi-center study for one year (trial B)
Blinding used: The surgeons and the patients knew about the surgeries, etc., but great effort was made to preserve and check the statistics with a non-biased statistician
Intervention: Laparoscopic adjustable gastric banding (LAGB) surgeries
Statistical analysis:
- Means with standard deviations, Student T-tests, linear regressions and weight loss in percentages
- Fisher's exact test was used to compare complication rates between trials A and B
- The significance level was at P≤0.05.

Data Collection Summary:

Timing of measurements: Baseline, six, 12, 24, 36 months and lost to follow-up information
Dependent variables
- Variable 1: Weight-loss
- Variable 2: Complication rate
- Variable 3: Death rate.
Independent variables: LAGB.

Description of Actual Data Sample:

Initial N: Trial A (N=292); Trial B (N=193)
Gender:
- Males 45 in Trial A; 35 Trial B
- Female 247 Trial A; 158 Trial B.
Attrition (final N): 70.5% retention rate for trial A; 73.6% retention rate for Trial B
Age: Approximately 39 years with an SD of 8.2 years in Trial A; 41.5 years with an SD of 9.4 years in Trial B
Ethnicity: The vast majority of the subjects were Caucasian. The remainder included African Americans, Hispanics, Asians and other ethnic groups.
Anthropometrics: Trial A average BMI was 47.4kg per m² (SD of 7kg per m²); Trial B average BMI was 46.6kg per m² with SD of 7.8kg per m².
Location: Multi-center study across many clinics in the USA.

Summary of Results:

Trial A: Three-Year Follow-up Data and Trial B One-Year Follow-up Data

Weight Loss

At one-year post-surgery, the mean weight loss among trial A and trial B patients was 23.6 and 23.7kg, respectively. At three years post-surgery, the mean weight loss in trial A patients was 25.4kg.
Using the last value carried forward, for all 292 patients in trial A and all 193 patients in trial B, the BMI was 47.4±7kg per m² to 39.0±7.3kg per m² and from 46.7±7.8 to 38.4±7.6kg per m² (Trial B), respectively for the subjects at one-year follow-up data points
Unfortunately, there was minimal further change at three years (39.0±8.5kg per m²) in trial A. Thus, weight was lost rapidly at first and then the weight loss plateaued 12 months post-surgery.

Complication Rate

At one year, 76% of patients in Trial A and 66% of the patients in Trial B had complications, mostly related to upper GI symptoms. By nine years after surgery, 33% of trial A subjects had their devices removed because of complications or inadequate weight loss.
The complication rate was highest during the first year and declined thereafter
The types of complications included: Band slippage, pouch dilatation, stoma obstruction insufficient weight loss, erosions and various, but rare conditions.

Death Rate

Two deaths occurred among patients enrolled in trial A. Neither death was directly related to this surgery.
One death was due to mixed drug intoxication after a car accident and the second death was due to multiple pulmonary emboli.

Author Conclusion:

Laparoscopic adjustable gastric banding systems are a viable option for morbidly obese patients. However, safety information beyond a decade is lacking and efficacy beyond three years is undetermined. Nevertheless, this procedure does produce weight loss and it may be a partial solution to a life-long struggle with morbid obesity.

Funding Source:

University/Hospital:

California State University, University of California-San Francisco

Reviewer Comments:

Excellent study, well-written in every way
Unfortunately, the attrition rate was higher than desired, but the authors made every attempt to report the data that they had on each subject.

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?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	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)?	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?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes