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MNT: Weight Management (2015)

Barratt R, Frost G, O'Boyle A, Millward J, Truby H. Use of sibutramine to assist obese women with weight loss can be successful in dietitian-led clinics: another tool in the dietitian's toolbox. J Human Nutrition and Dietetics. 2008; 21: 248-255. PubMed ID: 18477180
Study Design:
Case Control Study
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • To investigate differences in weight loss outcomes in obese women with type 2 diabetes (T2D) compared to those without T2D attending a dietitian-led lifestyle clinic
  • To investigate whether there were any beneficial effects on weight loss by the addition of sibutramine in women who had failed to achieve weight loss goals in the lifestyle clinic
  • To compare effects of sibutramine on weight loss in obese women with and without T2D. 
Inclusion Criteria:
  • Attendance at dietitian-led lifestyle or pharmacotherapy clinics at Hammersmith Hospital NHS Trust, London
  • Female.
Exclusion Criteria:
  • No attendance at dietitian-led lifestyle or pharmacotherapy clinics at Hammersmith Hospital NHS Trust, London
  • Male.
Description of Study Protocol:


Recruited from Hammersmith Hospital NHS Trust, London.


Retrospective case-control study analyzing the data generated from the dietitian-led lifestyle and pharmacotherapy clinics at the Hammersmith Hospital NHS Trust, London. Practice at the Hammersmith Hospital is to initially offer a six-month lifestyle intervention to patients referred for weight loss. The intervention was led by a dietitian and focused on setting goals and achieving changes to diet and activity using motivational techniques to achieve a energy deficit. The six-month intervention included six one-on-one sessions with the dietitian and the overall aim was to achieve a 10% body weight loss over the intervention period. Those unsuccessful in losing weight using the lifestyle approach were screened by the dietitian for their suitability for pharmacotherapy using sibutramine. The patients continued to meet with the dietitian six times over the six-month intervention period with similar practices to the lifestyle clinic. Patients in the pharmacotherapy group had their blood pressure and heart rate measured every two weeks. Patients attending the lifestyle clinic had blood pressure and heart rate measured at baseline and again at six months. In both groups, weight was recorded at each appointment and fasting blood was drawn at baseline and at six months for analysis of glucose, glycohaemoglobin (HbA1c), cholesterol (high density and low density) and triacylglycerol. To allow for comparison across groups, the patients in the pharmacotherapy group were pair matched with those in the lifestyle group for age, ethnicity and presence or absence of diabetes.


Lifestyle and pharmacotherapy interventions led by a dietitian.

Statistical Analysis

  • Within group differences were explored using paired T-tests
  • Between group differences explored using either independent T-tests or analysis of variance
  • Prior weight loss achieved during unsuccessful lifestyle intervention was not included in analysis.
Data Collection Summary:

Timing of Measurements

  • Blood pressure and heart rate were measured every two weeks for patients in the pharmacotherapy group and at baseline and six months for patients in the lifestyle group
  • Weight was recorded at each appointment for both groups
  • Fasting blood was drawn at baseline and six months for analysis of glucose, glycohaemoglobin (HbA1c), cholesterol (high density and low density) and triacylglycerol for both groups.

Dependent Variables

  • Weight change (kg)
  • BMI change (kg/m2)
  • Percentage of body weight loss
  • Glycemic control (mmol per L-1)
  • HbA1c (percent)
  • Blood pressure (mm Hg)
  • Cholesterol (mmol per L-1)
  • High density cholesterol (HDL) (mmol per L-1)
  • Low density cholesterol (LDL) (mmol per L-1)
  • Total cholesterol (mmol per L-1)
  • Triacylglycerol (mmol per L-1).

Independent Variables

Method of nutrition intervention.

Control Variables

  • Diabetes diagnosis
  • Age
  • Ethnicity.
Description of Actual Data Sample:
  • Initial N: N=38 females
  • Attrition (final N): N=38 females


  • Sibutramine non-diabetic (SIO): 40.4±8.88 years
  • Sibutramine diabetic (SID): 43.67±11.84 years
  • Lifestyle non-diabetic (LO): 38.8±10.16 years
  • Lifestyle diabetic (LD): 48.89±8.72 years.


  • Sibutramine non-diabetic (SIO): Six white, three black and one Asian
  • Sibutramine diabetic (SID): Five white and four black
  • Lifestyle non-diabetic (LO): Seven white, two black and one Asian
  • Lifestyle diabetic (LD): Five white and four black.


No statical differences in age, weight, BMI or blood pressure between the groups at baseline


London, England.


Summary of Results:

Key Findings

  • All groups lost a significant amount of weight over the six-month treatment period
  • In the lifestyle-treated groups, those with T2D lost significantly less weight than those without T2D [5.26kg (4.54%) vs. 9.89kg (9.55%) (P<0.05)]
  • None of the patients with T2D managed to achieve the 10% weight loss target compared to 50% of those with simple obesity
  • For obese women who failed to lose weight via the lifestyle intervention, the addition of sibutramine resulted in similar body weight loss as their pair matched lifestyle-only successful counterparts (9.66% vs. 9.55%)
  • The corresponding T2D group who failed to lose weight via the lifestyle intervention indicated that the addition sibutramine resulted in significantly greater weight loss early on in its prescription (between week one and week 15, P<0.05) compared to those who were not taking this pharmacotherapy
  • After six months, difference in total weight loss between the T2D groups was not statically significant and mean weight loss of all T2D in the study was 6.4kg (5.81% body weight)
  • There was a non-significant trend of improvement in most biochemical markers and reduction in blood pressure for all groups 
  • Significant reduction from baselines levels of HbA1c and plasma glucose in those with T2D when treatment conditions were combined.
Variables BMI (kg/m2) % body weight loss Glucose (mmol L-1) HbA1C (%)
      Start End Start End
Sibutramine non-T2D group 4.07±2.98 9.66±1.74 5.24±0.66 5.24±0.86 5.41±0.62 5.09± 0.6*
Sibutramine T2D group 2.32±1.12 5.81±0.91 8.83±3.27 7.56±2.24 7.79± 1.5 6.78±2.16
Lifestyle non-T2D group 3.66±2.76 9.55±2.08 5.28±0.78 5.29±0.94 5.46±0.7 4.89±0.68*
Lifestyle T2D group 1.9±1.2 4.54±0.94 7.12±1.77 6.2±1.28 7.09±1.31 6.5±0.76
All T2D 2.11±1.15 5.18±2.77 7.93±2.65 6.84±1.87* 7.44±1.41 6.64±1.58*
All non-T2D 3.86±2.0 9.6±5.91 5.26±0.7 5.26±0.87 5.44±0.64 4.98±0.63**
All subjects 3.03±2.33 7.51±5.15 6.59±2.34 6.05±1.65* 6.47±1.49 5.83±1.46**

(* P<0.05, ** P<0.01).


Author Conclusion:
Not all obese women, particularly those with T2D, will derive benefit from lifestyle advice; those who are resistant to this approach may be assisted by pharmacotherapy.This study demonstrates that dietitians are able to take a lead role in the recommendations of prescription sibutramine and it is another tool for assisting those with obesity and T2D to achieve favorable outcomes where other interventions have failed.
Funding Source:
Government: UK Medical Research Council
Reviewer Comments:
Limitations include:
  • Small number of subjects
  • Unable to match subjects for all obesity-related co-morbidities such as arthritis that may impact the ability to lose weight.
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) 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.) Yes
  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%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  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? Yes
  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? Yes
  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? 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? 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? 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)? No
  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? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes