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MNT: Weight Management (2015)

Riecke B, Christensen R, Christensen P, Leeds A, Boesen M, Lohmander L, Astrup A, Bliddal H. Comparing two low-energy diets for the treatment of knee osteoarthritis symptoms in obese patients: a pragmatic randomized clinical trial. Osteoarthritis and Cartilage / OARS, Osteoarthritis Research Society, 2010; 18: 746-754. PubMed ID: 20206314
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To compare whether there would be an advantage in using a very-low energy diet (VLED, 415kcal per day), compared with a low-energy diet (LED, 810kcal per day) on short-term follow-up in obese patients with knee osteoarthritis.
Inclusion Criteria:
  • This report is part of the larger randomized controlled trial on the influence of weight loss or exercise on cartilage in obese knee osteoarthritis (OA) patients
  • Patients were recruited from the outpatient clinic at the Department of Rheumatology at Frederiksberg Hospital, Frederiksberg, and through newspaper and website advertisements from November 2007 to August 2008.
Eligible participants were:
  1. Obese, with body mass index greater than 30kg/m2
  2. Over 50 years of age
  3. Primary knee osteoarthritis, diagnosed according to the American College of Rheumatology criteria with clinical signs and symptoms, as well as radiologically or arthroscopically verified OA in one or both knees.
Exclusion Criteria:
Patients were excluded if there was:
  • Previous or planned total knee replacement in the target knee
  • Surgical procedures on a knee within three months prior to enrollment
  • Phamacological therapy with weight reducing drugs
  • Lack of motivation to lose weight
  • Inability to speak Danish fluently
  • Mental state impeding compliance with the program.
Description of Study Protocol:


  • Patients were recruited as existing patients in an outpatient rheumatology clinic, through newspaper ads or through a website
  • Interested participants were screened in a phone interview.


  • Random assignment to one of two treatment groups: LED or VLED
  • Both groups received identical nutrition education and behavior therapy in 1.5-hour weekly sessions through the first eight weeks of specified diet and an additional eight weeks of hypo-energy diet consisting of normal food plus meal replacements
  • Nutrition education and management was provided by dietitians.

Blinding Used

  • Formula packets for the LED and VLED were not marked for nutritional content
  • Assignment was randomized and assessment criteria were the same for all participants.


  • The VLED and the LED consisted of the the Cambridge Diet (the Cambridge Health and Weight plan, UK)
  • VLED participants were instructed to mix the formula with water, while the LED participants were instructed to mix the packet with skim milk: The VLED diet provided 415kcal per day and the LED provided 810kcal per day.

Statistical Analysis

  • Randomization based on minimization according to gender, BMI and age to ensure homogeneity between intervention groups
  • SAS software (v. 9.1.3 Service Pack 4; SAS Institue Inc., Cary, NC, USA)
  • Intention-to-treat analysis of data
  • Wald Z-test for proportions
  • Wald test for statistical significance (P<0.10) with chi-square and Fisher's exact test, when needed.
Data Collection Summary:

Timing of Measurements

  • Enrollment, eight weeks and 16 weeks
  • Participants in this study will be monitored for a full year as part of the larger study.

Dependent Variables

  • OMERACT-OARSI response (Outcome Measures in Rheumatology Clinical Trials and Osteoarthritis Research Society International)
    • Pain
    • Disability
    • Global
    • Weight change
    • Weight change percentage
    • Change in BMI.?
  • KOOS (Knee injury and Osteoarthritis Outcome Score)
    • Pain change
    • Symptom change
    • Change in Activities of Daily Living (ADL)
    • Change in sports or recreation
    • Change in Quality of Life (QOL)
    • SF-36.
  • Change in physical component
  • Change in mental component.

Independent Variables

  • Age
  • Sex
  • Duration of OA
  • Bone mineral content
  • Smoker status
  • Plasma glucose
  • C-reactive protein
  • Kellgren and Lawrence radiographic reading (grades 1 through 4).

Control Variables

The Low Energy Diet Group was the "control" in the assessment of potential advantage between the two groups.

Description of Actual Data Sample:
  • Initial N: 388 pre-screened for participation; 187 were not eligible, nine declined to participate, 192 enrolled (37 men, 155 women)
  • Attrition (final N): 175 completed (91%)
  • Age: 62.5±6.4 (50.0 to 77.9) years
  • Ethnicity: Danish
  • Other relevant demographics: All similar between groups, except smoking status (12.5% in the VLED Group and 3.6% in the LED Group)
  • Anthropometrics: Groups were similar, with an initial BMI of 37.3±4.8kg/m2 (30.1kg/m2 to 54kg/m2)
  • Location:  Frederiksburg Hospital, Denmark.
Summary of Results:

Key Findings

  • Both groups were similarly and overall compliant with program
  • Both groups lost an average of 12% body weight
  • There were no statistically significant differences between the groups in response to the OMERACT-OARSI criteria
  • There were no statistically significant differences between the groups in KOOS responses, though both showed minimal perceptible clinical improvements in pain, symptoms, function in daily living, sports or recreation and quality of life
  • There was an overall improvement in both the physical and mental components of the SF-36 in both groups, but there was statistically significant greater improvement in the mental component of the SF-36 in the VLED Group (P=0.01).
Author Conclusion:
  • The study showed a highly significant improvement in symptoms in obese patients with knee osteoarthritis following a 16-week intervention consisting of Low Energy Diet program leading to a majority of the participants losing more than 10% of their body weight
  • There was not a significant difference in weight losses between Low Energy and Very Low Energy Diet treatment groups.
Funding Source:
Cambridge Manufacturing Company
Food Company:
Pharmaceutical/Dietary Supplement Company:
University/Hospital: The Parker Institute, Frederiksberg Hospital, Denmark
In-Kind support reported by Industry: Yes
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? 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")? Yes
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? 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? 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
  5.4. 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? 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
  6.2. 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? 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
  7.2. 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? 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? No