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:

To examine the long-term effects of prolonged weight loss after restrictive bariatric procedure on ghrelin and leptin concentrations and their possible correlation with changes in body mass, insulin sensitivity and secretion parameters derived from the modified oral glucose tolerance test (OGTT).

Inclusion Criteria:

Subjects with a body mass index (BMI) greater than 40kg per m².

Exclusion Criteria:

Subjects with endocrine or general conditions not related to obesity that may reduce longevity.

Description of Study Protocol:

Recruitment

Not described by author.

Design

Endocrine and metabolic tests were collected prior to and at six months and 12 months after laparoscopical adjustment gastric banding (LAGB)
Fasting concentrations of insulin, C-peptide, leptin and ghrelin, along with a modified OGTT (75g glucose dissolved in water) were collected at these intervals
Routine laboratory tests were collected prior to LAGB and for every three months after surgery.

Blinding Used

Intervention

After intial screening tests subjects underwent an LAGB
Subjects were seen every three months post-surgery for nutritional surveillance
The nutritional management was comprised of a liquid diet for four weeks after surgery, followed by a prescription of a solid low-fat diet and a list of rules to avoid vomiting
The first LAGB inflation was performed six to eight weeks post-surgery and further band adjustments were made only in the case of weight stabilization (variation of less than 4kg during the last two months) and low vomiting frequency in the outpatient surgical department.

Statistical Analysis

Results are expressed as means ± SD
Multivariate analysis of variance and post hoc testing by Dunn-Sidak pair-wise comparisons compared differences of mean values
Student's T-test was used to analyze the difference between variables pre- and post-surgical intervention
Differences between data on ghrelin were compared with the relationship between ghrelin and other parameters
No correction for multiple testing was applied due to the exploratory nature of the study
P<0.05 was used to indicate statistical significance.

Data Collection Summary:

Timing of Measurements

Data was collected pre-surgically and routine laboratory tests and weights were collected every three months post-surgery for 12 months
Endocrine and metabolic tests were collected before surgery and at aix and 12 months.

Dependent Variables

BMI (kg per m²)
Waist circumference (cm)
Systolic blood pressure (mm Hg)
Diastolic blood pressure (mm Hg)
Fasting blood glucose (mg per dL)
Fasting plasma C-peptide (ng per mL)
Fasting triglycerides (mg per dL)
Total cholesterol (mg per dL)
LDL cholesterol (mg per dL)
HDL cholesterol (mg per dL)
Glutamic pyruvic transaminase (GPT) (U/L)
γ-glutamyl transferase (γGT) (U/L)
BSR (pmol per L^-1-min^-1)
Total insulin secretion (nmol per L^-1·3 h^-1
HIE (%)
OGIS (ml.min^-1·m^-2)
Disposition index (nmol per m²)
Adaptation index (nmol per minute^-1·m^-2)
Plasma leptin (ng per ml)
Plasma ghrelin (pmol per L).

Independent Variables

LAGB surgery
Nutritional dietary intevention

Control Variables

None noted by author.

Description of Actual Data Sample:

Initial N: 18 (15 females, 3 males)
Attrition (final N): 18 (15 females, 3 males)
Age: Mean 35.5±12 years
Ethnicity: Not noted by author
Other relevant demographics: Not noted by author
Anthropometrics: None noted by author
Location: Vienna, Austria

Summary of Results:

Anthropometric, Biochemical and OGTT-Derived Parameters of Severely Obese Subjects Before and After LAGB

Variables	Before LAGB mean (SD)	6 months after LAGB mean (SD)	Statistical Significance from baseline to 6 months P-value	12 months after LAGB mean (SD)	Statistical Significance from baseline to 12 months P-value
N (female/male)	18 (15/3)	18 (15/3)		18 (15/3)
BMI kg/m²	45.27 (5.32)	37.24 (5.30)	<0.0001	33.5 (5.48)	<0.0001
Waist circumference (cm)	141.50 (37.48)	117.0 (8.48)	<0.001	108.0 (0.0)	<0.0001
Systolic BP (mm Hg)	151.50 (14.72)	130.67 (12.7)	<0.0001	126.67 (14.35)	<0.0001
Diastolic BP (mm Hg)	93.78 (12.26)	83.06 (6.67)	<0.0001	76.78 (9.63)	<0.0001
Fasting blood glucose (mg/dL)	124 (63)	101 (37)	<0.01	100 (33)	NS
Fasting plasma C-peptide (ng/ml)	404 (95)	339 (96)	<0.01	275 (80)	<0.0001
Fasting triglycerides (mg/dL)	177 (52)	150 (50)	<0.01	137 (52)	<0.01
Total cholesterol (mg/dL)	198 (45)	201(42)	NS	203 (42)	NS
LDL cholesterol (mg/dL)	136 (44)	125 (38)	NS	132 (41)	NS
HDL cholesterol (mg/dL)	52 (16)	50 (15)	NS	52 (10)	NS
GPT (U/L)	20 (20)	13 (7)	NS	9 (4)	<0.05
γGT (U/L)	24 (28)	18 (14)	NS	12 (4)	<0.05
N (females/male)	18 (15/3)	18 (15/3)		14 (13/1)
BSR (pmol/L^-1-min^-1)	82.2 (19.3)	69.1(19.5)	<0.01	55.9 (16.1)	<0.001
Total insulin secretion (nmol/L^-1·3 h^-1	30.4 (10.0)	27.3 (6.4)	NS	21.1(7.2)	<0.05
HIE (%)	63.4 (11.8)	74.2 (8.1)	<0.001	73.8 (10.2)	<0.05
OGIS (mL.min^-1·m^-2)	343.0 (86.4)	405.1(86.5)	<0.05	442.6 (94.8)	<0.01
Disposition index (nmol/m²)	22.8 (3.7)	17.8 (2.7)	NS	15.7 (11.0)	NS
Adaptation index (nmol/min^-1·m^-2)	5.55 (0.79)	6.08 (0.53)	NS	4.77 (2.71)	NS
Plasma leptin (ng/mL)	27.6 (9.5)	17.7 (10.0)	<0.0001	12.7 (5.1)	<0.0001
Plasma ghrelin (pmol/L)	234 (53)	232 (53)	NS	261(72)	<0.05

Other Findings

Fasting plasma leptin correlated negatively with fasting glucose (R=-0.486; P=0.04), hemoglobin A1c (R=-0.506; P=0.01) and positively with OGIS (R=+0.576; P=0.01) before LAGB. These relationships disappeared at six and 12 months after LAGB.
Fasting ghrelin correlated negatively with fasting plasma insulin at six months (R=-0.495; P=0.04) and 12 months (R=-0.632; P=0.02), but not before LAGB (R=-0.295; P=0.24). Fasting ghrelin correlated positively with HIE at six months (R=+0.546; P=0.02) and 12 months (R=+0.571; P=0.03), but again not before the LAGB (R=0.242; P=0.34).
Changes in ghrelin tended to correlate negatively with changes in BMI (R=-0.425; P=0.07) after six months and correlated significantly after 12 months LAGB (R=-0.495; P=0.04). Changes in ghrelin correlated with changes in plasma triglycerides at six months (R=-0.567; P=0.018), but not at 12 months (R=-0.343; NS).
No significant relationships were observed between fasting ghrelin and other parameters of insulin secretion.

Author Conclusion:

Prolonged weight loss results in a rise of fasting ghrelin concentrations, which correlate negatively with fasting insulin concentrations but not with insulin sensitivity
The decreased fasting insulin concentrations could be due to increased hepatic insulin extraction instead of altered insulin secretion.

Funding Source:

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

Small number of subjects (N=18)
There was no diet control group to compare analyses
The study does not allow discrimination of whether the observed changes are primarily due to weight loss or to the surgical technique of LAGB.

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
	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
	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
	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
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
	1.	Was the research question clearly stated?	Yes
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.1.	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
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
	1.3.	Were the target population and setting specified?	Yes
	2.	Was the selection of study subjects/patients free from bias?	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
	2.1.	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
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	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
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
	3.	Were study groups comparable?	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)	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?	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
	3.3.	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?	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
	3.5.	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")?	Yes
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	Yes
	4.	Was method of handling withdrawals described?	Yes
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	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
	4.2.	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
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	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?	Yes
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	Yes
	5.	Was blinding used to prevent introduction of bias?	Yes
5.	Was blinding used to prevent introduction of bias?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	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.)	Yes
	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.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	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
	5.4.	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?	Yes
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	Yes
	6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?	Yes
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
	6.1.	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
	6.2.	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
	6.3.	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
	6.4.	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
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments 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
	6.7.	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?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	Yes
	7.	Were outcomes clearly defined and the measurements valid and reliable?	Yes
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
	7.1.	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
	7.2.	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
	7.3.	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
	7.4.	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
	7.5.	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
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	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.	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
	8.1.	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
	8.2.	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
	8.3.	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
	8.4.	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)?	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
	8.6.	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
	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.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	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.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes