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 aim of the present prospective study was to compare the Roux-en-Y gastric bypass (RYGBP) to a modified biliopancreatic diversion (BPD) in an exclusively non-superobese population, regarding safety and efficacy.

Inclusion Criteria:

Clinically severe obesity, with a BMI of 35 to 50kg per m².

Exclusion Criteria:

Not discussed.

Description of Study Protocol:

Recruitment

From June 1994 to December 2005, 676 patients with clinically severe obesity at a morbid obesity unit underwent various bariatric surgical operations
130 patients with BMI 35 to 50kg per m², were prospectively chosen to undergo RYGBP or BPD with RYGBP (variant of standard BPD).

Design

65 patients were chosen to undergo RYGBP and 65 chosen to undergo BPD with RYGBP (variant of standard BPD)
All patients underwent complete follow-up including nutritional, laboratory and clinical evaluation at one, three, six, 12 and 24 months.

Blinding Used

Abstract specifies that subjects were randomly selected for either RYGBP or BPD, but methods section does not describe randomization. Instead, it specifies that they were prospectively chosen to undergo each surgery type.
The methods section does not specifiy how the 130 of 676 patients were selected for the study.

Intervention

Gastric surgery

RYGBP Group: The main characteristics were a 15±5ml gastric pouch, biliopancreatic limb of 60cm, Roux limb of 100cm and common limb the remainder of the small intestine
BPD with RYGBP Group: The main characteristics of the variant of the BPD were a 15±5ml gastric pouch, biliopancreatic limb of 150 to 200cm distal to Treitz' ligament depending on the full length of the small intestine, common limb of 100cm and alimentary limb the remainder of the small intestine.

Note: Cholecystectomy was always added to the BPD procedure, but was only performed in RYGBP patients when cholelithiasis was present.

Statistical Analysis

Variables were analyzed using Fisher's exact test for the investigation of difference in proportions
Mean values of the parameters were compared using Student's T-test
All reported P-values are two-sided and significant at a level of P<0.05.

Data Collection Summary:

Timing of Measurements

Patients underwent complete follow-up including nutritional, laboratory and clinical evaluation at one, three, six, 12 and 24 months post-operatively.

Dependent Variables

Primary Outcome: Post-operative metabolic deficiencies and resolution of co-morbidities
Secondary Outcomes: Weight loss.

Independent Variables

RYGBP Group: The main characteristics were a 15±5ml gastric pouch, biliopancreatic limb of 60 cm, Roux limb of 100cm and common limb the remainder of the small intestine
BPD with RYGBP Group: The main characteristics of the variant of the BPD were a 15±5ml gastric pouch, biliopancreatic limb of 150 to 200cm distal to Treitz' ligament depending on the full length of the small intestine, common limb of 100cm and alimentary limb the remainder of the small intestine.

Note: Cholecystectomy was always added to the BPD procedure, but was only performed in RYGBP patients when cholelithiasis was present.

Control Variables

After surgery all patients received:

Daily multivitamin and mineral supplement
Calcium supplementation was prescribed at a dose of 1g per day for RYGBP patients and 2g per day for BPD patients.

Description of Actual Data Sample:

Initial N: 130 patients (81% women)
Attrition (final N): 130 patients (81% women)
Age: No significant difference
- RYGBP: 33.0±1.2 years
- BPD: 34.8±1.4 years.
Ethnicity: Not discussed
Other relevant demographics: Co-morbidities
- RYGBP: 5.6±20.3
- BPD: 4.7±0.3 (P<0.01).
Anthropometrics:
- BMI: RYGBP: 44.6±0.4kg per m²; BPD: 45.3±0.4kg per m²
- Excess weight: RYGBP: 60.7±1.5kg; BPD: 64.2±1.2kg.
Location: Greece.

Summary of Results:

**WEIGHT LOSS RESULTS FOR 12 AND 24 MONTHS**
	RYGBP (N=65)	BPD (N=65)	P-Value
12 Months
% Follow-Up	95%	98%
Mean BMI±SEM	27.7±0.64	26.1±0.35	0.025
Mean % EWL±SEM	73.7±1.87	83.1±1.44	0.0001
<25% EWL	0	0	-
>50% EWL	90.3%	100%	0.70
24 Months
% Follow-Up	95%	86%
Mean BMI±SEM	28.0±0.67	24.1±1.08	0.0018
Mean % EWL±SEM	72.6±2.05	83.1±1.69	0.0003
<25% EWL	0	0	-
>50% EWL	88.71%	100%	0.68

Procedure was defined as successful when the percent excess weight loss (% EWL) was greater than 50% with a BMI less than 35kg per m², and as completely unsuccessful when %EWL was less than 25%. By this definition all BPD patients were successful compared to 88.7% of RYGBP patients at the two-year follow-up.
No statistically significant differences were observed between the two groups in early and late non-metabolic complications
Anemia was present in 33.3% of RYGBP patients and in 40% of BPD patients (P<0.0001)
Post-operative decrease in mean hemoglobin levels as compared to pre-operative levels was significant in both groups (RYGBP P=0.003; BPD P<0.0001)
Post-operative decrease in mean vitamin B₁₂levels was statistically significant in both groups (RYGBP P=0.0007; BPD P=0.0004).
Pre-operative mean albumin levels was statistically significant in both groups (P<0.0001), a difference that remained significant post-operatively (P=0.0001)
BPD patients had significantly lower mean cholesterol values at the two-year follow-up (P<0.0001)
At the two-year follow-up, glucose intolerance, hypercholesterolemia, hypertriglyceridemia and sleep apnea had completely resolved in both groups
Diabetes Type 2 completely resolved in all BPD patients.

Author Conclusion:

This study shows that both RYGBP and BPD are safe and effective procedures in non-superobese patients
Weight loss after BPD is better than after RYGBP, as is the resolution of diabetes and hypercholesterolemia
The nutritional deficiencies that occurred following this type of BPD were not severe and were not significantly different between the two procedures. Thus, both procedures may be offered to non-superobese patients.

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?		???
	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?	???
	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?	???
3.	Were study groups comparable?		???
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	No
	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?		???
	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
	5.3.	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)?	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?	???
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