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PDM: Metabolic Syndrome (2013)

Citation:

Zhang SX, Guo HW, Wan WT, Xue K. Nutrition education guided by Dietary Guidelines for Chinese Residents on metabolic syndrome characteristics, adipokines and inflammatory markers. Asia Pac J Clin Nutr. 2011; 20(1): 77-86.

PubMed ID: 21393114
 
Study Design:
Cluster Randomized Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To test whether the Dietary Guidelines for Chinese Residents have beneficial effects on anthropometric and metabolic variables in patients with the metabolic syndrome.

Inclusion Criteria:
  • Metabolic syndrome patients in two urban districts in Shanghai
  • Subjects with metabolic syndrome defined by International Diabetes Federation guidelines.
Exclusion Criteria:
  • Those with severe psychological disorders, physical disabilities, cancer, cardiovascular diseases, Type 1 diabetes, Alzheimer's disease or dementia
  • Those currently diagnosed with tuberculosis, AIDS and other communicable diseases.
Description of Study Protocol:

Recruitment

  • 2,800 subjects aged 30 to 65 years were randomly selected from candidates listed in the residential registration records from two urban districts in Shanghai
  • A standardized questionnaire was administered by a home interviewer to screen possible metabolic syndrome patients, resulting in 612 eligible participants
  • Eligible participants underwent a physical exam and lab measurements, which yielded 272 subjects with diagnosed metabolic syndrome
  • Patients in one district were chosen as the intervention group (N=130) and the other as the control group (N=142). 

Design

Randomized controlled trial.

Blinding Used

Implied with measurements, no blinding was reported.

Intervention

  • The intervention group received a monthly lesson on Dietary Guidelines for Chinese Residents, as well as monthly individual consultation for a period of one year
  • Energy intake was recommended to the intervention subjects according to age range and physical activity, and quantities and kinds of food for each energy level  were suggested 
  • Subjects were also advised to reduce sodium, simple sugar and fat intake, and to increase intake of whole grain, deep colored vegetables and fruits
  • Recommended composition of dietary regimen was:
    • Carbohydrate: 55% to 60%
    • Protein: 12% to 15%
    • Fat: Less than 30%
    • Saturated fat: Less than 10%
    • Cholesterol: Less than 300mg per day
  • The control group received instruction on choosing healthy food every four months but were not offered individualized consultation. 

Statistical Analysis

  • Pearson chi-square test was used to test the male and female difference between the two groups
  • Wilcoxon rank sum test was used to test the age difference between groups
  • Linear mixed-effects model (XTREG procedure in Stata software) was used to test differences of change between groups
  • Significance was defined at the level of P<0.05.
Data Collection Summary:

Timing of Measurements

Measurements were taken at baseline and at the end of the one-year study.

Dependent Variables

  • Anthropometric (weight, height, waist circumference and hip circumference): BMI and waist:hip ratio calculated
  • Biochemical measurements for fasting glucose and lipids were determined and the homeostasis model assessment of insulin resistance was then calculated by the formula: FG (mmol per L) x Fasting insulin (μ IU per ml)/22.5
  • Human adiponectin, tumor necrosis factor-α, leptin and C reactive protein in serum were determined
  • Nutrition knowledge, attitude and practice was evaluated using a KAP questionnaire and physical activity survey (International Physical Activity Questionnaire-short-IPAQ-s).

Independent Variables

  • The intervention group received a monthly lesson on Dietary Guidelines for Chinese Residents, as well as monthly individual consultation for a period of one year. 

    • Energy intake was recommended to the intervention subjects according to age range and physical activity, and quantities and kinds of food for each energy level  were suggested 
    • Subjects were also advised to reduce sodium, simple sugar and fat intake, and to increase intake of whole grain, deep colored vegetables and fruits
    • Recommended composition of dietary regimen was:
      • Carbohydrate: 55% to 60%
      • Protein: 12% to 15%
      • Fat: Less than 30%
      • Saturated fat: Less than 10%
      • Cholesterol: Less than 300mg per day
  • The control group received instruction on choosing healthy food every four months but were not offered individualized consultation
  • Nutrition intake data was collected via a 24-hour recall for three days (two week days and one weekend day) for nutrient analysis. 

Control Variables

For the intervention group, those currently on medication were reminded of the importance of taking medication for hypertension. Those who made any changes in medication were excluded in further evaluation.

Description of Actual Data Sample:
  • Initial N: 272 (intervention group N=130, control group N=142)
  • Attrition (final N): 235 
    • Intervention group: N=115 (34 male, 81 female)
    • Control group: N=120  (41 male, 79 female)
  • Age: 30 to  65 years old
  • Ethnicity: Chinese
  • Other relevant demographics: Living in two urban districts of Shanghai
  • Anthropometrics: Comparison of mean anthropometric measures and biochemical measures for the intervention and control groups were similar
  • Location: Shanghai, China.
Summary of Results:

Key Findings

  • Significant differences in waist circumference and waist-to-hip ratio were observed between two groups with the intervention group showing the greatest mean improvement
  • HDL-C increased only in the intervention group and this change was significantly different compared to the control group
  • Mean adiponectin increased significantly in the intervention group and the change was significantly different within that group compared to the control group
  • Leptin and tumor necrosis factor-a decreased in both groups but the change of tumor necrosis factor-a in the intervention group was significantly different compared to that of the control group.

 

Anthropometric and Metabolic Variables with Medication-changed Patients Excluded

 
Variables Time Point Control Group   Intervention Group  Comparison Between Group P Value  Change Difference Between Group P Value
Sex, male/female   35/68 23/51 0.685♦  -
Age baseline 52±6 56±5 <0.001♦♦  -
BMI, kg/m²

baseline 

 26.7±2.9 27.0±3.1 0.639  
0.869
  one year 26.5±2.9* 26.7±3.0* 0.687
Waist circumference, cm baseline 93.9±7.9 92.4±7.6 0.211 0.001
 
  one year 91.9±7.6*** 88.4±8.1*** 0.003
Waist-to-hip ratio baseline 0.92±0.06 0.90±0.05 0.261 <0.001 
 
  one year 0.92±0.06 0.89±0.06*** <0.001
Blood pressure, mm Hg  Systolic baseline 129±14 130±15 0.340 0.489
 
  one year 130±15 130±15 0.782
mm Hg diastolic baseline 86±9 87±9 0.383 0.721
 
  one year 85±9 87±10 0.216
Glucose, mmol per L baseline 5.5±1.7 5.4±1.7 0.637 0.193
 
  one year 5.4±1.5 5.1±1.1* 0.146
Insulin, μIU per L baseline 11.7±5.0 12.7±9.2 0.500 0.429
 
  one year 12.7±8.1 12.5±7.3 0.846
HOMA-IR baseline 2.9±2.0 3.3±3.8 0.508 0.239
 
  one year 3.1±2.6  2.8±2.0  0.489
Serum Lipids, mmol per L Triglyceride baseline 2.1±1.2 2.0±1.2 0.450 0.330
 
  one year 1.9±1.0** 1.6±1.0*** 0.119
Total cholesterol baseline 5.5±1.0 4.3±1.1 <0.001 <0.001
 
  one year 4.9±0.9*** 4.6±0.8** 0.081
HDL-C baseline 1.2±0.4 1.2±0.4 0.332 0.343
 
  one year 1.2±0.2 1.3±0.3 0.028
Adiponectin, ug per ml baseline 4.8 ±3.7 4.2±2.9 0.283 0.176
  one year 4.9 ±4.3 5.2±4.2* 0.784
Leptin, ng per ml baseline 15.9 ±9.1 14.4±8.7 0.202 0.052
  one year 14.9 ±6.8 11.4±6.3*** 0.003
CRP, ug per ml baseline 8.6 ±11.2 9.1±11.4 0.804 0.821

 

 

 one year 8.5 ±11.0 9.3±14.0 0.609
TNF-α, pg per ml baseline 112 ±23 117±30 0.171 <0.001
  one year 106 ±23* 90±13*** <0.001

For P range when comparing the difference within group. * P<0.05; **P<0.01; ***P<0.001; Pearson x² test; ♦♦ Wilcoxon rank sum test. BMI, body mass index; HOMA-IR, homeostasis model assessment of insulin resistance; HDL-C, high density lipoprotein cholesterol; CRP, C-reactive protein; TNF-a, tumor necrosis factor-a. 

Other Findings

  • Knowledge, attitude and practice improved in the intervention group
  • Sitting hours decreased similarly in both groups during the study, but no differences were observed between two groups
  • Nutrient intake analysis revealed that means of energy intake, fibers, carbohydrates and proteins increased significantly and were higher in the intervention group compared to the control group
  • The vegetable-to-total-energy ratio and fruits-to-total-energy ratio were significantly higher in the intervention group than in the control group
Author Conclusion:

This study confirmed that Dietary Guidelines for Chinese Residents had beneficial effects on anthropometric, lipids, adipokines and inflammatory markers in patients with the metabolic syndrome.

Funding Source:
University/Hospital: Dept. of Nutrition and Food Hygiene, School of Public Health, Fudon University, Shanghai, China
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.) 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? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  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? 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? 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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. 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