MNT: Comparative Effectiveness of MNT Services (2009)


Timlin MT, Shores KV, Reicks M. Behavior change outcomes in an outpatient cardiac rehabilitation program. J Am Diet Assoc. 2002; 102: 664-671.


PubMed ID: 12008991
Study Design:
Non-Randomized Controlled Trial
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To evaluate the effectiveness of nutrition education delivered by a dietitian within a cardiac rehabilitation program.


Inclusion Criteria:
  • Men and women; age range between 35 to 85
  • Physician referral to an outpatient cardiac rehabilitation program following diagnosis or treatment for myocardial infarction, percutaneous transluminal coronary angiography, coronary artery bypass graft or stable angina.
Exclusion Criteria:

Exclusion criteria included:

  • Attending fewer than 12 cardiac rehabilitation sessions
  • Heart or lung transplant diagnosis
  • Valve replacement diagnosis only
  • Atrial septal defect diagnosis only
  • Recent diagnosis of transient ischemic accident or cerebral vascular accident
  • Active psychiatric complications
  • Untreated psychosocial/behavioral problems
  • Illiteracy
  • Limited English language proficiency.
Description of Study Protocol:


All eligible outpatients in the cardiac rehabilitation programs at Fairview Southdale and Fairview Ridge hospital were asked to participate in the study during a five- to six-month period.


Subjects were assigned according to participation in cardiac rehabilitation programs in two community hospitals within an integrated health care system. Subjects enrolled at Fairview Southdale were assigned to the control group. Those enrolled at Fairview Ridges were assigned to the treatment group.

Constraints on physical space and clinician time dictated the non-randomized nature of the study design.


  • Control Group: Patients received usual non-individualized nutrition education from cardiac rehabilitation therapists. Nutrition education included exposure to handouts, viewing of videotapes and access to recipe and reference books on an inconsistent basis. Occupational therapists or exercise physiologists led group discussions or showed videotapes during the subjects' scheduled one-hour cardiac rehabilitation session.
  • Treatment Group: Attended two group nutrition education classes and one individual diet counseling session, all led by the same dietitian. Nutrition education classes were developed based on results from a needs-assessment process involving interviews with previous cardiac rehabilitation program participants. Learning objectives focused on developing behavioral capability needed to comply with the American Heart Association Step II diet recommendations. The individual diet counseling session involved a review of diet habits and goal-setting.  

Statistical Analysis

  • Analysis of variance was used to analyze differences between three time periods
  • Differences in categorical variables between control and treatment groups were assessed using X2 test
  • Pearson's correlation analysis was also performed to examine relationships among variables
  • The significance level was P<0.05.
Data Collection Summary:

Timing of Measurements

Subject participation in a six-week cardiac rehabilitation program. Measurements were taken at baseline, six weeks and at a three-month follow-up.

Dependent Variables

  • Changes in fat, saturated fat, cholesterol
  • Carbohydrate intake
  • Restaurant eating habits, as assessed by the diet habit survey
  • Changes in cardiac diet self-efficacy
  • Changes in health-related quality of life.

Independent Variables

  • Control Group: Received usual non-individualized nutrition education from cardiac rehabilitation therapists
  • Treatment Group: Attended two group nutrition education classes and one individual diet counseling session, all led by the same dietitian.
Description of Actual Data Sample:
  • Initial N: 130 subjects entered the study. 104 completed (20% drop-out rate, 82% male)
    • Treatment Group, N=54
    • Control Group, N=50.
  • Attrition (final N): 86 subjects returned questionnaires at three months (Treatment Group, N=47; Control Group, N=39)
  • Age: Mean age in both groups, 62 years
  • Ethnicity: Not described
  • Other relevant demographics: Mean between groups: 81% married; 17% high school or less; 40% some college; 21.5% college graduate; 22% post-graduate studies.


  • No significant differences between control and treatment groups, except in education
  • Weight
    • Control Group: 196±42 lbs
    • Treatment Group: 193±35 lbs.
  • BMI
    • Control Group: 29.4±5.4
    • Treatment Group: 29.3±4.7.


St. Paul, Minnesota, USA.

Summary of Results:

Dietary Intake Scores Bases on Responses to the Diet Habit Survey

Dietary Score Control Group Treatment Group Analysis of Variance (P-Value)
Program entry (N=39) Discharge from program (N=39) 3-month follow-up (N=39) Program entry (N=47) Discharge from program (N=47) 3-month follow-up (N=47) Time Group-by-time
Cholesterol-Saturated Fat Index (CSI) per Day
Percentage of Energy from Carbohydrate
Restaurants and Recipes
Total Diet Habit Survey Score

  • CSI significantly decreased in both groups, with most subjects moving toward a dietary fat intake in line with current recommendations of 30% or less of total energy from fat
  • Percentage of energy from carbohydrate significantly increased in both groups from entry to discharge, with most subjects moving toward a dietary carbohydrate level of 55% of energy or more
  • The treatment group did not improve to a greater extent than in the control group, over time, in the effects for either the CSI or percentage of energy from carbohydrate
  • Younger age was associated with greater improvement in the total diet habit survey scores for the control (P< .05) and treatment (P<0.0001) groups and with improvement of energy from carbohydrate in the control (P<0.05) and treatment (p<0.0001) groups
  • BMI decreased over time was positively correlated with improvements in the CSI for the control (P<0.05) and treatment (P<0.05) groups
  • There were no differences between groups over the three time periods (baseline, six weeks, and three-month follow-up).
Author Conclusion:

Nutrition education within an outpatient cardiac rehabilitation program can improve dietary choices at restaurants and boost self-confidence in the ability to adhere to a lipid-lowering diet.




Funding Source:
University/Hospital: University of Minnesota
Reviewer Comments:
  • In both groups, education level was significantly different at baseline, however an initial repeated-measures analysis of variance, with education level included as a factor, showed that level of education did not impact results in eating behavior or self-efficacy scores between groups
  • Dropout rate was 20%
  • Non-random design allows for the possibility of selection bias, which could account for differences found.
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? 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.) 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