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 is to compare weight loss, status of co-morbidities, medication usage and quality of life in patients before and at one year after laparoscopic adjustable gastric banding (LAGB).

Inclusion Criteria:

NIH criteria for bariatric surgery (BMI greater than 35kg per m²or BMI less than 35kg per m²with co-morbidities)

Exclusion Criteria:

Does not meet NIH guidelines for bariatric surgery.

Description of Study Protocol:

Recruitment: Patients from Northwest Weight Loss Surgery Center
Design: Prospective cohort study. The research nurse practitioner obtained informed consent and interviewed subjects to collect data on demographics, co-morbidities, treatments and medications and administer the SF-36 (quality of life questionnaire). Height and weight were measured and BMI calculated. Patients were encouraged to select a reasonable personal goal weight at the pre-operative visit. Metropolitan Life Tables were used to determine ideal body weight (IBW). Lap-band was inserted laproscopically. Patients returned for follow-up visits and adjustment of bands.
Blinding used: N/A
Intervention: Lap-Band bariatric surgery
Statistical analysis: Continuous variables were compared using unpaired T-tests. Categorical variables were compared with the Chi-square test.

Data Collection Summary:

Timing of Measurements

Measurements were taken at baseline and one year.

Dependent Variables

Weight loss: Measured by BMI and absolute weight (kg); reported as excess weight loss and percent goal weight)
Co-morbidities: Arthritis, asthma, depression, diabetes, gastro-esophageal reflux disease (GERD), hyperlipidemia, hypertension, hypothyroidism, joint or back pain, polycystic ovarian syndrome (PCOS), sleep apnea and urinary stress incontinence
Medication
Quality of Life: Questionnaire SF-36 scale measuring general health, physical functioning, social functioning, mental health, physical role limitations, emotional role limitations, bodily pain and vitality.

Independent Variables

Surgical procedure (laparoscopic adjustable gastric banding).

Control Variables

Medical, nutritional, psychological, and surgical education.

Description of Actual Data Sample:

Initial N: 195 patients (female 82.8%; male 17.2%)
Attrition (final N): 149 patients (77.2%)
Age: 43.8±10.1 years (range 19 to 70 years)
Ethnicity: 94.9% White
Other relevant demographics: 65.1% married; 39% had outpatient surgery and went home the same day
Anthropometrics: Baseline BMI: 45.8kg per m²; baseline weight: 126.9kg
Location: Northwest Weight Loss Surgery, Kirkland, WA.

Summary of Results:

Table 1: Change in BMI and Weight Loss

Variables	Baseline (N=195)	1 Year Follow Up (N=179)
BMI	45.8±7.7kg/m²	32.3±7.0kg/m²
Weight	126.9±23.7kg	98.9±11.0kg
Weight Loss	N/A	28.0±11.0kg
% Excess Weight Loss	N/A	45.7%±27.1%

There were significant reductions in co-morbidities compared to %EWL in the following:
- Reduced depression (P<0.0001)
- Hypertension (P<0.0001)
- Joint or back pain (P=0.0201)
- Sleep apnea (P=0.0162).

At one year post-surgery, the percentage of patients who had decreased or discontinued medications:
- Arthritis (59%)
- Asthma (82%)
- Depression (26%)
- Diabetes (81%)
- GERD (74%)
- Hyperlipidemia (32%)
- Hypertension (49%)
- Joint or back pain (65%)
- Stress incontinence (80%)

There were significant changes in Quality of Life SF-36 scores on four scales after surgery related to %EWL:
- General Health (GH): P=0.0006
- Mental Health (MH): P=0.0484
- Emotional Role (RE): P=0.0511
- Vitality (VT): P=0.0122.

There were significant improvements in SF-36 and the following co-morbidities:
- Joint or back pain and GH, Social Functioning (SF), MH, Physical Role (RP), Bodily Pain (BP) and VT
- Arthritis and GH, Physical Functioning (PF), RP and VT
- Hypertension and GH, SF, RP and VT
- Depression & SF, MH and RE
- Hypothyroidism and SF, MH and RE
- PCOS and PF, SF and RP
- Sleep apnea and RE.

Author Conclusion:

This cohort of primarily white females with morbid obesity demonstrated a high level of improvement in their obesity, resolution of co-morbidities, decreased medication usage, and improved quality of life (QoL) after LAGB
All patients lost weight, however, significant improvements in their co-morbidities and QoL were not necessarily related to % EWL.

Funding Source:

Industry:

Northwest Weight Loss Surgery

Other:

University/Hospital:

University of Washington

Reviewer Comments:

The author's study objective, design and outcome were clearly described. The tables included demographics and study variables. The LAGB procedure was described. This was a statistically strong study.
However, the strength of the study could be further enhanced by including an analysis which includes the relationship weight loss has to the education component or the number of support groups the patients attended. The author mentioned, but did not describe the extensive multidisciplinary screening and education before surgery. The author also mentioned support groups twice a month. In addition to the LAGB procedure, education is important and the outcome variable, weight loss, could be affected by the education before and during the year following surgery.
Excess weight loss (EWL) was not explained very well. How was weight measured and were the scales used to measure the weight the same at baseline and follow-up? It is confusing as to whether excess weight loss is equivalent to percent weight change. The author did explain the variability in using the EWL.
Withdrawals were explained due to patients moving away, however exact information was not given. One year follow-up visits were attended by 77.2% of patients. It is suggested that 80% of the patients complete the follow-up visit for a strong study.

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?		No
	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?	???
	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?	No
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.)	No
	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?	Yes
	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?	No
	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?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	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?	No
	6.6.	Were extra or unplanned treatments described?	No
	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?	N/A
	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?	Yes
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