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 study was to evaluate the effect of laparoscopic adjustable gastric banding on weight loss, type 2 diabetes and hypertension in obese patients taking medications for type 2 diabetes or hypertension.

Inclusion Criteria:

All Patients Who Met the Following Criteria Were Included in the Study Group

Adult (18 years or older)
Body mass index (BMI) of 35kg/m² or greater and co-morbidities or BMI 40kg/m² or greater with or without co-morbidities
Underwent laparoscopic adjustable gastric banding using Lap-Band System
Completed one year of post-surgery follow-up
Were taking medication for type 2 diabetes or hypertension.

Inclusion Criteria for Type 2 Diabetes

Clinical diagnosis of type 2 diabetes
Were taking diabetic medication before surgery.

Inclusion Criteria for Hypertensive Patients

All patients taking anti-hypertensive medications for clinical indications at initial study visit.

Exclusion Criteria:

Patients with type 2 diabetes and hypertension who were not taking diabetic or hypertensive medications prior to Lap-Band surgery were excluded from the study.

Description of Study Protocol:

Design

Patients who underwent laparoscopic adjustable gastric banding (using Lap-Band) and were taking medications for type 2 diabetes or hypertension were included in study
Patients with type 2 diabetes were divided into two groups at baseline:
- Those who had type 2 diabetes for less than five years
- Those who had type 2 diabetes for more than five years.

Intervention

Patients underwent laparoscopic adjustable gastric banding using Lap-Band System (Inamed Health, Santa Barbara, CA) from October, 2000 to April, 2003.

Statistical Analysis

Analysis of variance or regression methods were used to examine influence of disease status on weight loss
Fisher's exact tests were used to analyze the relationship between two categorical variables, such as duration of disease and disease resolution
Change in HbA1c status between baseline and subsequent time-points was examined using McNemar tests.

Data Collection Summary:

Timing of Measurements

Patients were measured every two to three months for the first two years post-surgery, then annually thereafter.

Dependent Variables

Weight loss: Post-surgery follow-up weight measurements were obtained in clinic or, if patient was not available to come into the clinic, from doctor's office scales, telephone calls or e-mail. Weight loss was recorded as change in BMI or percentage of excess weight lost (%EWL), calculated as the percentage of excess weight from ideal body weight.
Diabetes control: Pre-surgery HbA1c concentrations were prospectively recorded; follow-up HbA1c values were obtained from patient medical records. Values were measured at baseline and months 12, 18, 14 and 36. Diabetes was considered "resolved" in patients who achieved normal HbA1c levels following surgery and required no diabetes medication. Diabetes was considered "improved" in patients who reduced HbA1c levels or reduced diabetes medication dosage.
Hypertension control: Assessment of hypertension medications was performed by a doctor in clinic. Hypertension was considered "resolved" in patients who became normotensive (diastolic blood pressure of less than 90mm Hg and systolic blood pressure less than 140mm Hg) without medication. Hypertension was considered "improved" in patients who were normotensive with a reduction in antihypertensive medication usage or dosage.

Independent Variables

All Lap-Band Systems were placed laparoscopically with the exception of one patient who had large fatty heptomegaly.

Description of Actual Data Sample:

Initial N: 840 patients underwent Lap-Band surgery (83% females, 17% males); 413 completed at least one year post-surgery follow-up (patients with type 2 diabetes, 53; patients taking antihypertensive medication, 189)
Attrition (final N): N (year 1), 402; N (year 2), 91; N (year 3), 24
Age: Mean age, 41.8 years (range 18 to 68 years old)
Other relevant demographics: Mean pre-operative HbA1c concentration was 7.25% (5.6 to 11) for patients in diabetes group.

Anthropometrics

Diabetes group: Mean pre-operative body mass index (BMI), 48.7kg/m²
Hypertensive group: Mean BMI, 47.4kg/m²
Cohort group: Mean BMI = 46.2kg/m².

Location

Dalton, Georgia, USA (PC and Hamilton Medical Center).

Summary of Results:

	Diabetes Group	Diabetes Cohort	Hypertensive Group	Hypertensive Cohort
Body mass index (BMI) in kg/m²
Pre-operative	48.7	-	47.4	-
12 months	38.2	-	37.1	-
18 months	36.9	-	34.3	-
24 months	38.4	-	31.0 (P=0.017)	-
Percent excess weight lost (%EWL)
12 months	39.2	41.2	41.2	40.8
18 months	46.7	54.2	52.7	53.1
24 months	52.6	63.3	64.5 (P=0.012)	58.0
36 months	-	-	68.4	53.1

Other Findings

%EWL was significantly better in more recent-onset diabetes patients (less than five years) compared with %EWL in patients with diabetes for more than five years (42.5% vs. 32.3% at 12 months, respectively) and (59.0% vs. 36.2% at 18 months, respectively)
Of 53 patients with diabetes and at least a one-year follow-up, 66% went off all diabetes medications at 12 months, 70.6% at 18 months and 80% at 24 months. HbA1c changed from 7.25% at baseline to 5.87 at 12 months, 5.68% at 18 months, 5.58% at 24 months and 5.33% at 36 months.
Patients in whom diabetes did not resolve experienced lower %EWL as compared to those with resolved diabetes. The average %EWL in those with unresolved diabetes was 27.0% at 12 months, 27.4% at 18 months and 26.5% at 24 months, as compared to 45.0% at 12 months, 53.9% at 18 months and 59.1% at 24 months in those with resolved diabetes (P<0.001 at 12 and 18 months and P=0.005 at 24 months).
Of patients with hypertensive (N=189) and at least one-year follow-up, 59.8% (N=113) went off all anti-hypertensive medications at 12 months, 68.8% (N=66) at 18 months and 74.0% (N=37) at 24 months. Hypertension improved in 38.0% (N=72) at 12 months, 28.1%(N=27) at 18 months, 22.0% (N=11) at 24 months. Hypertension did not resolve or improve in 2.1% (N=4) at 12 months, 3.1% (N=3) at 18 months and 4.0% (N=2) at 24 months.
Patients with resolved hypertension experienced higher %EWL, as compared to those without complete hypertension resolution: at 12 months, 46.4% vs. 33.2% (P<0.001); At 18 months, 57.8% vs. 41.3% (P<0.001) and at 24 months, 69.0% vs. 51.8% (P<0.005).

Author Conclusion:

The author states that his study found that laparoscopic adjustable gastric banding (LAGB) was more effective for resolution of type 2 diabetes and hypertension in severely and morbidly obese patients. Because LAGB is less invasive than other obesity surgeries, there is less risk of peri- or post-surgical complications. However, type 2 diabetes and hypertension are most effectively treated through weight loss, regardless of how weight loss is achieved.

Funding Source:

Reviewer Comments:

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?	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?		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%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	No
	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?	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?	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?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	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?		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?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	No
	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)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	No
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
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