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SSPSM: Compliance (2014)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To compare a nutritionally complete prepared meal plan that meets national dietary guidelines to usual-care dietary therapy for hypertension, dyslipidemia and glycemic control.
Inclusion Criteria:
  • People with essential hypertension, dyslipidemia, type 2 diabetes mellitus or any combination of these conditions
  • Between the ages of 25 years and 70 years of age
  • Body mass index up to 42kg/m2
  • Meet one of the criteria for diagnostic measures of hypertension, dyslipidemia and type 2 diabetes mellitus
  • Provide written informed consent.
Exclusion Criteria:
  • Chronic life-threatening diseases
  • Serious abnormality on physical examination or diagnostic testing
  • Insulin treatment
  • Gastrointestinal disorders that would interfere with the absorption or excretion of dietary products
  • Women who were pregnant, lactating or not practicing birth control
  • Substance or alcohol abuse.
Description of Study Protocol:
  • Recruitment: People with essential hypertension, dyslipidemia, type 2 diabetes mellitus or any combination of these conditions were recruited through outpatient clinical advertisements
  • Design: Randomized controlled trial
  • Blinding used: Implied with measurements.

Intervention

  • Subjects randomized to one of two groups for 10 weeks
    • Cardiovascular Risk Reduction Dietary Intervention Group (CCNW)
      • Participants completed a four-week baseline period that preceded the 10-week treatment period. During this time, participants were asked to maintain their usual diets, were seen weekly for blood pressure and weight management and completed two three-day food records.
      • The prescription for the CCNW diet was calculated using the Harris-Benedict equation and self-reported height, weight, age and sex to estimate the person's energy needs adjusted for activity level and desire for weight maintenance or loss. The macronutrient composition was 22% energy from fat, 58% energy from carbohydrate and 20% energy from protein. The meals include five breakfast selections, 12 lunches and 10 dinners plus 10 snacks.
      • Participants ordered their choice of meals according to the amount of prescription weekly via phone
      • This group was instructed to consume one CCNW breakfast, lunch and dinner supplemented with one self-selected serving each of fruit, vegetables and low-fat dairy. One selection from a bonus list of alcohol or fruit and dairy was allowed. The CCNW meal plan was fortified to meet 100% of the RDA for most nutrients for adults, with the exception of vitamin D (77% RDA) and copper (91% RDA).
    • Usual Diet Group
      • This group followed the same as above, except the diet was prescribed a set number of servings from the American Dietetic Association's exchange list categories comprised of breads and starches, fruits, low-fat dairy, vegetables and lean meats. Participants could select one serving daily from the bonus list in the CCNW program.
  • Participants received nutrition education and diet adherence support during visits at Weeks Two and Eight and by telephone at Weeks Four and Six
  • Nutrition counseling including written instructions was provided to all participants at Week Zero.

Statistical Analysis

  • The primary end-points for the effect of the diet were blood pressure, plasma lipids, glucose and change in body weight
  • The study had 80% power with a two-sided alpha error level of 5% to detect differences between treatment groups of two mmHg in systolic blood pressure
  • A repeated-measures analysis of variance model stratified by diagnosis was used to analyze differences between baseline and treatment periods
  • An analysis of covariance model was developed to adjust for the effect of weight on study outcome measures, but an interaction between weight change and treatment group was observed compromising the validity of the model.
Data Collection Summary:

Timing of Measurements

Participants were seen at eight and 10 weeks for clinical and laboratory measurement and to review three-day food records.

Dependent Variables

  • Blood pressure
  • Weight
  • Total cholesterol was measured using the colorimetric enzymatic endpoint method
  • High density lipoprotein (HDL) was analyzed using the heparin manganese method
  • Low density lipoprotein (LDL) was calculated using the Friedewald algorithm
  • Insulin was measured using a solid phase radioimmunoassay
  • Total serum homocysteine levels were determined using high performance liquid chromatography (HPLC).
Independent Variables
  • Subjects randomized to one of two groups for 10 weeks
    • Cardiovascular Risk Reduction Dietary Intervention Group (CCNW)
      • Participants completed a four-week baseline period that preceded the 10-week treatment period
      • During this time, participants were asked to maintain their usual diets, were seen weekly for blood pressure and weight management and completed two three-day food records
      • The prescription for the CCNW diet was calculated using the Harris-Benedict equation and self-reported height, weight, age and sex to estimate the person's energy needs adjusted for activity level and desire for weight maintenance or loss
      • The macronutrient composition was 22% energy from fat, 58% energy from carbohydrate and 20% energy from protein
      • The meals include five breakfast selections, 12 lunches and 10 dinners plus 10 snacks
      • Participants ordered their choice of meals according to the amount of prescription, weekly via phone
      • This group was instructed to consume one CCNW breakfast, lunch and dinner supplemented with one self-selected serving each of fruit, vegetables and low-fat dairy. One selection from a bonus list of alcohol or fruit and dairy was allowed.
      • The CCNW meal plan was fortified to meet 100% of the RDA for most nutrients for adults, with the exception of vitamin D (77% RDA) and copper (91% RDA).
    • Usual Diet Group
      • This group followed the same as above, except the diet was prescribed a set number of servings from the American Dietetic Association's exchange list categories, comprised of breads and starches, fruits, low-fat dairy, vegetables and lean meats
      • Participants could select one serving daily from the bonus list in the CCNW program.
  • Participants received nutrition education and diet adherence support during visits at Weeks Two and Eight and by telephone at Weeks Four and Six
  • Nutrition counseling, including written instructions, was provided to all participants at Week Zero
  • Food records were analyzed at the coordinating center with a licensed copy of Nutrition Data System, v. 2.8.
Description of Actual Data Sample:
  • Initial N: 251 randomized (127 to CCNW Meal Plan Group, 65% women; 124 to Usual Care Diet Group, 60% women)
  • Attrition (final N): 243 subjects. No follow-up information was available for five subjects in the CCNW Group and three in the Usual Care Diet Group.
  • Age: Mean age in the CCNW Meal Plan Group, 51.1±10.3 years vs. 53.9±9.5 years in the Usual Care Diet Group.

Ethnicity

  • CCNW Group: 9% black, 3% Hispanic, 2% Native American, 2% Asian or Pacific Islander, 84% white
  • Usual Care Group: 3% black, 6% Hispanic, 2% Native American, 1% Asian or Pacific Islander, 88% white.

Other Relevant Demographics
Not reported.

Anthropometrics
Groups were similar at baseline.

Location
The trial was conducted at six medical centers in the United States and Canada.

 

Summary of Results:

Key Findings

  • Lipoproteins, carbohydrate metabolism, blood pressure and weight improved on both plans
  • Mean estimated energy intake in men decreased by 761±75.0kcal per day with the CCNW plan and by 550±74.6kcal per day with the usual care diet (P<0.001 within each group)
  • Mean estimated energy intake in women decreased by 423±56.0kcal per day with the CCNW plan and by 461±54.4kcal per day with the usual care diet (P<0.001 within each group)
  • There were no significant differences in energy intake between groups
  • While there were no differences in protein intake between groups, subjects on the CCNW plan had a greater decrease in fat (men, 12.8±7.0%; women, 11.6%±6.8%), compared with the Usual Care Group (men, 6.9±7.4%; women, 7.0±6.8%; P<0.001), related to a greater increase in carbohydrate
  • Mean differences between baseline and follow-up for the CCNW plan and the usual-care plan respectively, were:
    • Total cholesterol, -0.41±0.64mmol and -0.20±0.50mmol per L (between group, P<0.01)
    • Plasma glucose, -0.7±1.7mmol and -0.3±1.3mmol per L (P<0.05)
    • Systolic blood pressure, -5.2±10.0mmHg and -4.7±9.0mmHg (P=0.67)
    • Diastolic blood pressure, -3.8±5.9mmHg and -2.2±5.5mmHg (P<0.05)
    • Homocysteine, -1.3±3.8mcmol and 0.2±3.4mcmol per L (P<0.01).
  • The CCNW plan led to greater weight loss than the usual care diet (-5.5±3.8kg vs. -3.0±3.2kg, P<0.0001)
  • With the CCNW diet plan, there was a greater decrease in sodium (P<0.001) and cholesterol (P<0.001) than in the Usual Care Group
  • Both groups had significant decreases in total fat and saturated fat intakes (both, P<0.01)
  • Increases in the dietary intakes of calcium, iron, potassium, magnesium, folic acid and vitamins A, B6, B12, C, D and E were all significantly greater in the CCNW plan (P<0.001)
  • The CCNW plan resulted in higher serum levels of vitamin B12, vitamin E and folic acid than the usual care diet, but there were no differences for vitamins A, B6 or C
  • Serum vitamin A declined in both groups (P<0.001)
  • Despite comparable self-reported compliance with prescribed energy intake (within ±100kcal per day) in both groups, a significantly higher proportion of CCNW participants achieved recommended goals for fat consumption (P<0.001), compared to those following the usual care diet.
Author Conclusion:
The nutritionally complete CCNW plan offers greater improvements in lipids, blood sugars, homocysteine and weight loss than usual-care diet therapy. This pre-packaged comprehensive nutrition program can augment both the prescription and practice of optimal dietary therapy.
Funding Source:
University/Hospital: Oregon Health Sciences University
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? 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? 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? 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)? No
  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