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Mediterranean Diet and the Prevention and Treatment of CVD

Citation:

Toobert DJ, Glasgow RE, Strycker LA, Barrera M Jr., Radcliffe JL, Wander RC, Bagdade JD. Biologic and quality-of-life outcomes from the Mediterranean Lifestyle Program: a randomized clinical trial. Diabetes Care, 2003 Aug; 26 (8): 2,288-2,293.

PubMed ID: 12882850
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To study the effectiveness of the Mediterranean Lifestyle Program, a comprehensive lifestyle self-management program (Mediterranean low-saturated-fat diet, stress management training, exercise, group support and smoking cessation), in reducing cardiovascular risk factors in post-menopausal women with type 2 diabetes.

Inclusion Criteria:
  • Female
  • Diagnosis of type 2 diabetes for at least six months
  • Post-menopausal
  • Living independently
  • Having a telephone
  • Able to speak English
  • Not developmentally disabled
  • Living within 30 miles of Eugene, Oregon.
Exclusion Criteria:
  • Being under 75 years of age
  • Planning to move from the area within the study's time span.
Description of Study Protocol:

Recruitment

Letter was sent to eligible participants from their primary care providers, followed by a follow-up phone call inviting them to participate. 

Design

  • Participants were randomized to either a usual care or treatment (MLP) condition
  • MLP participants took part in an initial three-day retreat, followed by six months of weekly meetings to learn and practice program componenets.

Blinding Used

No. 

Intervention

  • Mediterrean Lifestyle Program (MLP), which addressed diet, physical activity, stress management, social support and smoking
  • The program context, materials, logo, music, intervention space and key components (including diet) were designed to produce a "Mediterranean feel"
  • To build a sense of community, a social support intervention delivered by professional and lay leaders was included.

Statistical Analysis

  • ANOVAS
  • MANCOVAS.
Data Collection Summary:

Timing of Measurements

  • Baseline
  • Six months.

Dependent Variables

  • HbA1C: Ion-exchange high-performance liquid chromatography, using the BioRad Variant II Instrument 
  • Plasma fatty acids: Extracted twice with five ml chloroform/methanol and transesterified with boron trifluoride and methanol
  • BMI: Converted from morning digital scale
  • Waist-to-hip circumference: Hip girth was measured at the maximum circumference of the buttocks. To compute waist-to-hip ratio, waist was measured in centimeters was divided by hips measured in centimeters
  • Blood pressure: A random-zero sphygmomanometer, using the Heritage protocol
  • Flexibility: Trunk flexion and shoulder range of motion
  • Quality of life: Medical Outcomes Study (MOS) Short-Form General Health survey.

Independent Variables

MLP (Meditarranean Lifestyle Program).

Control Variables

Usual care.

Description of Actual Data Sample:
  • Initial N: 279
  • Attrition (final N): 245 (12% attrition rate)
  • Age: Post-menopausal women 75 years of age or younger
  • Ethnicity: Not stated
  • Other relevant demographics: Living within 30 miles of Eugene, Oregon
  • Anthropometrics: No differences between groups on these measurements
  • Location: Eugene, Oregon.
Summary of Results:

Variables

Treatment Group
Measures and confidence intervals

Control Group
Measures and confidence intervals

Statistical Significance of Group Difference

HbA1C

Baseline

7.43 ± 1.3

7.40 ±1.48

Yes
P=0.001

6 months 7.07 ± 1.11 7.38 ± 1.33

Triglyceride

Baseline

202.38 ± 149.06 171.59 ±110.56

No

6 months

176.82 ± 113.98

157.93 ± 88.2

Total Cholesterol

Baseline

191.57 ±37.84

181.77 ±36.69

No

6 months 187.61 ±35.60 180.72 ±39.73
BMI

Baseline

35.34 ±7.93 34.87 ±8.20

Yes
0.015 MANCOVA

6 months

34.97 ± 7.85

35.07 ±7.85

Other Findings

  • Six-month differences on serum lipids between UC and MLP did not acheive statistical significance, but favored the MLP condition
  • MANCOVA across all quality-of-life dimensions revealed overall improvements in favor of the MLP participants
  • MLP participants' blood pressure and flexibility improved and UC participants' conditions slightly worsened
  • MANCOVA for the plasma fatty acid profile neared statistical significance (P=0.059).
Author Conclusion:
  • The authors did demonstrate that the MLP produced consistent and significant greater improvements than the UC in all the five targeted behavioral risk factors: Eating patterns, physical activity, social support, stress management and coping, smoking cessation.
  • The authors did state their limitations in ethnic diversity, even though their sample was heterogenous in socio-economics, income, education and 96% covered by medical insurance
  • The authors also stated that they reduced the intensity of their MLP from their initial study because of the inverse relation between program intensity and reach.
Funding Source:
Government: NHLBI
Reviewer Comments:
  • This research article was very organized in its written delivery, stated clinical improvements and limitations and also stated other research questions to pursue
  • The authors were very honest about the concerns with intensity of an MLP and participation interest also.
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? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
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.) 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.) 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? 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? 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? ???
  6.6. Were extra or unplanned treatments described? ???
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? ???
  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? ???
  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)? ???
  8.6. Was clinical significance as well as statistical significance reported? N/A
  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