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MNT: Comparative Effectiveness of MNT Services (2009)

Citation:

Reid R, Fodor G, Lydon-Hassen K, Slovinec D'Angelo M, McCrea J, Bowlby M, Difrancesco L. Dietary counselling for dyslipidemia in primary care: results of a randomized trial. Can J Diet Prac Res. 2002; 63: 169-175.

PubMed ID: 12493139
 
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 compare the effectiveness of physician advice vs. dietitian advice for a fat-reduced diet (AHA Step II) and compare the effectiveness of dietitian advice for a fat-reduced diet (AHA Step II) vs. dietitian advice for a soluble fiber-enhanced diet (more than 10g per day).

Inclusion Criteria:
  • Physicians approached patients they thought would be candidates for dietary therapy on the basis of recent blood lipid results and other risk factors for CAD, as per Canadian recommendations.
  • Volunteers from the practices of 18 primary care physicians
  • Men aged 40 to 70 and women aged 50 to 70, free of CVD, were eligible. 
Exclusion Criteria:

People with LDL-cholesterol above six mmol per L, triglycerides (TG) above four mmol per L or diabetes mellitus and those using lipid-lowering medications.

Description of Study Protocol:

Recruitment

A total of 188 patients were asked by their physician to participate and were contacted by a study coordinator. Following telephone prescreening, 156 potential participants were scheduled for a screening session; of these 148 attended and 37 were excluded (10 were diabetic and 27 had lipid profiles that did not meet eligibility criteria). The remaining 111 volunteers were randomly assigned to a study group.  

Design

A medical and lifestyle history (smoking status, exercise habits, stress and coping, alcohol and caffeine intake) was taken: A fasting (more than 12 hours) blood sample was drawn to determine a lipid profile and body weight was measured.  A three-day food record (from two weekdays and one weekend day) was obtained to assess eating behaviors. Participants were randomly assigned to a physician advice fat-reduced diet group, a dietitian advice fat-reduced diet group or a dietitian advice fiber-enhanced diet group using a random numbers table.

Blinding Used

Not described.

Intervention

  • Physician advice fat-reduced diet group and the dietitian advice fat-reduced diet group received dietary advice based on the American heart Association Step II guidelines
  • Dietitian advice soluble fiber enhanced diet consumed one-third cup per day of psyllium-containing cereal and was advised to increase soluble fiber intake to over 10 grams per day.

Statistical Analysis

  • Baseline characteristics between groups were compared using one-way ANOVA and chi-square tests
  • End-of-treatment dietary behaviors were compared between groups using analysis of covariance (ANCOVA).
Data Collection Summary:

Timing of Measurements

Patients were followed for 26 weeks.

Dependent Variables

Changes in blood lipid parameters:

  • Total cholesterol (TC)
  • Low-density lipoprotein cholesterol (LDL-C)
  • High-density lipoprotein cholesterol (HDL-C)
  • TC and HDL ratio
  • Triglycerides.

Independent Variables

  • The physician-advised fat-reduced diet group received dietary counseling based on the AHA step II diet from their primary care physician during three office visits. Physicians were advised to devote each of the office visits entirely to dietary counseling. The first office visit, lasting 30 minutes, occurred within one week of baseline screening and the other two visits, each lasting 15 minutes, occurred eight and 16 weeks after first visit.
  • The dietitian-advised fat-reduced diet group received dietary counseling based on the AHA step II diet from a registered dietitian during three one-hour group sessions (10 participants per group) within one week and two and six weeks after baseline screening and during three 15-minute telephone sessions at 10, 18 and 23 weeks
  • The dietitian-advised fiber-enhanced diet group received counseling from a registered dietitian during three one-hour group sessions (10 participants per group) within one week and two to six weeks after baseline screening and during three 15-minute telephone calls at 10, 18, and 23 weeks.
Description of Actual Data Sample:
  • Initial N: 111 volunteer participants (41.2% female)
  • Attrition (final N): 86 volunteer participants
  • Age: 53.8 years
  • Ethnicity: Not described
  • Other relevant demographics: Daily smokers, 30.9%; exercising more than twice per week, 29%.

Anthropometrics

Mean body weight

  • Dietitian-advised fat-reduced diet group (N=35): 82.4 kg
  • Physician-advised fat-reduced diet group (N=38): 80.8 kg
  • Dietitian-advised fiber-enhanced diet group (N=38): 82.9 kg.

Mean BMI

  • Dietitian-advised fat-reduced diet group: 28.4
  • Physician-advised fat-reduced diet group: 28.7
  • Dietitian-advised fiber-enhanced diet group: 28.4.

Location

Ottawa, Canada.

Summary of Results:

Summary of ANCOVA Comparing Adjusted Mean Values (with 95% CI) for Percentage Change in Blood Lipid and Body Weight Parameters Over the 26-Week Treatment Period Considering Only Participants with Complete Data at Baseline and 26 Weeks (Efficacy Analysis)

  Dietitian-Advised Fat-Reduced Diet Group (N=26) Physician-Advised Fat-Reduced Diet Group (N=27) Dietitian-Advised Fiber-Enhanced Diet Group (N=33)

ANOVA
P-Value

Percentage Change in TC
-5.5
(9.3,1.7)
-3.4
(-5.4,0.6)
-5.6
(-9.0,-2.3)
0.62
Percentage Change in LDL-C
-7.9
(-12.8,-3.0)
-6.3
(-11.1,-1.5)
-5.6
(-10.0, -1.2)
0.79

Percentage Change in HDL-C

3.3
(-1.8, 8.5)
3.1
(-2.0,8.2)
-0.9
(-5.4,3.7)
0.38
Percentage Change in TC/HDL
-6.9
(-11.5,-2.2)
-5.4
(-10.0,-0.8)
-4.3
(-8.4,-0.1)
0.70
Percentage Change in TG
-6.2
(-19.4,7.0)
5.8
(-5.2,15.9)
-4.4
(-16.4,7.5)
0.40
Percentage Change in Body Weight
-3.6
(-4.9,-2.3)
-2.3
(-3.5,-1.1)
-1.3
(-2.4,-0.1)
0.003

Other Findings

  • All groups showed significant reductions in LDL cholesterol, TC-to-HDL ratio and body weight, compared to baseline. The magnitude of these changes was not significantly different between groups.
  • Reductions from baseline in TC and TG occurred only in the dietitian advice groups
  • None of the interventions caused a change in HDL cholesterol.

 

Author Conclusion:
  • Using dietary interventions that are potentially feasible within the health care system, both dietitians and physicians can help dyslipidemic patients make clinically meaningful changes in blood lipid levels
  • Soluble fiber enhancement of the usual diet lead to similar reductions in LDL cholesterol and TC-to-HDL cholesterol, compared to interventions focused on fat reduction.
Funding Source:
Industry:
Kellogg Canada
Food Company:
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? 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? 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? 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? 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? 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