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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 compare anthropometric, ultrasound (US) and computed tomography (CT) of body fat distribution under basal conditions and one year after laparoscopic adjustable gastric banding (LAGB), in order to propose a reliable and cheap method to follow patients undergoing bariatric surgery.

Inclusion Criteria:

Patients undergoing laparsocopic adjustable gastric banding must fulfill the following criteria:

  • Between the ages of 18 to 66 years 
  • Body mass index (BMI) greater than 40kg per m2 without comorbid conditions or BMI greater than 35kg per m2 with co-morbid conditions
  • History of at least two attempts to lose weight with dietary or medical measures followed by relapse of obesity.

 

Exclusion Criteria:
  • Obesity secondary  to endocrinopathies
  • Presence of gastrointestinal inflammatory diseases
  • Risk of upper gastrointestinal bleeding
  • Pregnancy
  • Alcohol or drug addiction
  • Previous or current malignancies.
Description of Study Protocol:
  • Recruitment: Patients who were undergoing LAGB at Istituto San Raffaele in Milano, Italy were recruited for re-evaluation of body fat distribution via different methods one year after procedure
  • Design: Before and after study
  • Blinding used: N/A
  • Intervention: LAGB using LapBand or INAMED
  • Statistical analysis: Differences in body weight and body fat distribution measures for each subject were assessed via student's T-test. Comparison between different body fat distribution measures was assessed via pairwise correlations.
Data Collection Summary:

Timing of Measurements

 Before LAGB and one year after LAGB.

Outcome and Comparison Variables

  • Visceral adipose tissue thickness: 
    • Measured by ultrasound (us VT)
    • Measured by computed tomography (ct VT).
  • Subcutaneous adipose tissue thickness:
    • Measured by ultrasound (us ST)
    • Measured by computed tomography (ct ST).
  • Visceral Area (VAT) measured by computed tomography
  • Subcutaneous Area (SAT) measured by computed tomography
  • Body weight (kg)
  • Height (m)
  • BMI
  • IBW determined by tables
  • Waist (cm)
  • Waist to hip ratio
  • Intraobserver coefficient of variation for ultrasound measurements.

 

Description of Actual Data Sample:
  • Initial N: 120 participants considered (27 males, 93 females)
  • Attrition (final N): 40 participants with before and after measures (5 males, 35 females)
  • Mean Age: 41.1±1.8 years
  • Ethnicity: N/A
  • Other relevant demographics: N/A
  • Anthropometrics: 
    • Mean body weight: 117.9±3.6kg  (259.4 lbs)
    • Mean height: 1.6±.01m (5.2 ft)
    • Mean BMI: 44.02±.59kg per m2
    • Mean waist circumference: 119.3±1.8cm
    • Mean waist to hip ratio: 0.87±.009.
  • Location: Italy.
Summary of Results:

 

  Before LAGB After LAGB*
Weight (kg)
117.9±3.6
96.9±3.1
BMI (kg/m2)
44.02±0.59
36.4±0.88
Waist (cm)
119.3±1.84
106.8±2.18
Visceral Thickness via Ultrasound
79.9±3.7
50.2±3.7
Subcutaneous Thickness via Ultrasound
53.2±1.51
38.8±1.76

*Differences were statistically significant at P<.001.

Mean Change in Body Weight One Year After LAGB (N=40)

21kg (46.2 lbs).

Mean Change in BMI One Year After LAGB (N=40)

7.6kg per m2.

Mean Change in Waist Circumference One Year After LAGB (N=40)

12.5cm.

Other Findings

  • Ultrasound and computed tomography measure for visceral fat thickness correlated at r=0.95
  • Ultrasound and computed tomography measures for subcutaneous fat thickness correlated at r=0.72
  • Waist circumference measure correlated with ultrasound and computed tomography measures for visceral fat at 0.81 and 0.69, respectively
  • Waist to hip ratio was weakly correlated with visceral thickness measures (r=0.51) and not significantly correlated with subcutaneous measures. 
Author Conclusion:
  • Evaluation of body fat distribution should be accomplished by ultrasound instead of computed tomography scan because of its lower cost and low exposure risk
  • Waist circumference stands as a reasonable surrogate of both methods, while waist to hip ratio seems to be poorly correlated to other measures of visceral fat.
Funding Source:
University/Hospital: University of Milan Medical School, Ospedal San Paulo, Ospedale, IRCC, Cattedra di Chirurgia, Ateneo Vita Salute San Raffaele (all Italy)
Reviewer Comments:
  • Authors provide a thorough and detailed explanation of how measures were taken and adequate procedures to assure reliability of measurements
  • It was unclear why only 40 patients were evaluated after one year of procedure instead of the initial 120 that underwent the surgery
  • Statistical analysis for all measures except evaluation of differences before and after surgery are adequate
  • Paired T-test instead of student's T-test should have been used to evaluate statistical difference for 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? 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? N/A
  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? No
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  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? N/A
  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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? No
  4.4. Were reasons for withdrawals similar across groups? N/A
  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? N/A
  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.) N/A
  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? 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? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  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? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? No
  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? No
  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)? N/A
  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? No
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