MNT: Disorders of Lipid Metabolism (2015)

Citation:

Delahanty LM, Sonnenberg LM, Hayden D, Nathan DM. Clinical and cost outcomes of medical nutrition therapy for hypercholesterolemia: A controlled trial. J Am Diet Assoc. 2001 Sep; 101(9): 1,012-1,023.

PubMed ID: 11573752
 
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 results and cost-effectiveness of a cholesterol-lowering protocol implemented by a registered dietitian with cholesterol lowering advice by physicians.

Inclusion Criteria:
  • 21 to 65 years of age
  • TC more than 5.2mmol per L
  • Less than 8.84mmol per L.
Exclusion Criteria:
  • Secondary medical conditions that can influence lipid levels (pregnancy, perimenopause, diabetes, thyroid disease or renal failure)
  • Use of medication that influence lipid levels (hypolipidemic drugs, thiazide diuretics, beta-blockers, estrogen therapy)
  • Hypertrigluceridemia (more than 4.52mmol per L)
  • Nutrition counseling for hypercholesterolemia by a registered dietitian in the previous year.
Description of Study Protocol:

Recruitment

Study candidates were identified through the Mass General Hospital Clinical Laboratory Information Center.

Design

Randomization using permuted bock randomization for either MNT from Registered Dietitian (RD) or usual care (UC) from physicians.

Intervention

  • MNT: Cholesterol-lowering counseling and treatment based on NCEP protocol developed from Ambulatory Nutrition Service at the Massachusetts General Hospital. Volunteers were to meet with RD from two to three visits in two to three months. If lipids were not in the target range after initial treatment, volunteers had an additional two to three follow-up visits to provide a full six-month diet intervention. The number of visits was based on an assessment of each volunteer’s eating habits, lifestyle, capabilities and motivation for change. They also received usual care by MD.
  • UC: Customary cholesterol-lowering advice from their healthcare provider in the ambulatory care setting, no contact with a RD. Use of lipid lowering drugs was prohibited in the six-month intervention.

Statistical Analysis

Analysis of covariance to control for gender and baseline value of variables used to assess group differences in change in dietary intake and the blood lipids at three, six and 12 months. T-tests (continuous variables) and Fisher's exact test (categorical variables) were used for baseline comparisons. T-tests were used for within group comparisons. Dietary intake and clinical outcomes correlations by Pearson product moment test. Wilcoxson test was used to compare patient satisfaction (groups) at baseline and at six months. All inter-group comparisons based on intent-to-treat analyses.

Data Collection Summary:

Timing of Measurements

Baseline, month three, six and 12.

Dependent Variables

  • Fasting lipids
  • Weight
  • Height
  • Patient satisfaction
  • Nutrient analysis of energy, fat, SF, PUFA, MUFA, cholesterol and fiber based on random 24-hour recalls. Nutrition interviewers did 24-hour recalls using the multiple pass interview methodology and a visual aid. Interviewers were blinded to interventions.
  • Physical activity recalls (total minutes of exercise) were done. Time spent with physician discussing cholesterol was recorded. Time spent with the RD was also recorded.

Independent Variables

  • MNT: Cholesterol-lowering counseling and treatment based on NCEP protocol developed from Ambulatory Nutrition Service at the Massachusetts General Hospital. Volunteers were to meet with RD from two to three visits in two to three months. If lipids were not in the target range after initial treatment, volunteers had an additional two to three follow-up visits to provide a full six month diet intervention. The number of visits was based on an assessment of each volunteer’s eating habits, lifestyle, capabilities and motivation for change. They also received usual care by MD.
  • UC: customary cholesterol-lowering advice from their healthcare provider in the ambulatory care setting, no contact with a RD. Use of lipid lowering drugs was prohibited in the six-month intervention.

 

Description of Actual Data Sample:
  • Initial N: 90 (60 men, 30 women) randomly assigned
  • Attrition (final N): 88 subjects; two men dropped out, one from each group
  • Anthropometrics: At baseline there were no differences in lipids, weight, BMI, activity levels or diet between treatment groups
  • Location: Massachusetts.
Summary of Results:

Diet Changes

  • At three and six months, the MNT group, compared to UC, achieved lower fat intakes (24% vs. 30% at three months, P<0.001; 25% vs. 29% fat at six months, P<0.01; 7% vs. 10% saturated fat, P<0.001)
  • Compared with baseline, MNT sustained a 7% to 8% decrease in total fat intake and a 4% decrease in SF intake at three months and six months. Reductions in total fat (P<0.01), SF (P<0.01), cholesterol (P<0.05) and energy (P<0.001) were seen at one year compared to baseline. However, the differences between the groups for energy and total fat were not significant.

Lipid Changes

  • MNT: 6% reduction in TC (6.19mmol per L at baseline vs. 5.77mmol per L at three and six months) and LDL-C (4.29mmol per L at baseline vs. 4.00mmol per L at three months and 3.98mmol per L at six months) at three and six months (P<0.05)
  • UC: No significant reduction in TC and LDL-C
  • The difference in change between groups was significant at three (P<0.001) and six (P<0.05) months.

Weight Loss

MNT lost 1.9 kg at 3 months, sustained at 6 months vs. no weight loss in UC (P<0.001).

Activity

  • MNT reported higher activity at three months compared to UC (P<0.05)
  • At one year, differences between groups for serum lipids, weight and activity were no longer significant. MNT received no additional counseling between six months and one year; however, they sustained a reduction in LDL-C (P<0.01) compared with baseline.

Time Spent Counseling

  • MNT: 90 minutes per volunteer in the first three months and 30 minutes in the second three months
  • Time spent with RD by month three was correlated with reductions in serum TC (R=-0.47, P=0.001) and LDL-C (R=-0.39, P=0.08) and with weight reduction (R=-0.34, P=0.02)
  • UC: One to two minutes per volunteer spent discussing TC and diet therapy.

Cost Outcomes

  • The calculated cost of dietitians’ effort for 90 minutes per volunteer during the first three months was an average of $217 to achieve a 6% reduction in total and LDL-C levels and an extra 3% reduction in saturated at intake
  • In the second three months, 30-minute average cost was $98, which sustained the decrease in total and LDL-C
  • The cost effectiveness ratio for MNT was $36 for each 1% decrease in total and LDL-C and $72 for each extra 1% decrease in saturated fat intake.

Satisfaction

MNT subjects were more satisfied with clinic visits, dietitian vs. physician understanding of lifestyle and eating habits, their knowledge of cholesterol, ability to manage cholesterol and eating habits than the UC groups (P<0.001). One third of the UC group sought out counseling, joined a weight loss group or went on medication (N=7) in the last six months of the trial.

Need for Lipid-lowering Drugs

At the end of 12 months, no subjects in the MNT group had lipid-lowering drugs while six of the 44 in the UC group needed medication that cost an average of $446 for months seven to 12 of the trial.

Author Conclusion:
  • The MNT group had a 6% decrease in total and LDL-cholesterol levels at month three compared with the UC group. The changes in total cholesterol levels were significantly greater in the MNT volunteers at three months and at six months compared with UC volunteers.
  • The MNT group lost more weight at three and six months and reported more activity at three months compared with the UC group. The MNT group achieved and sustained an 8% decrease un total fat (32% to 24%) and a 4% decrease in saturated fat intake (11% to 7%), which was statistically significant at three and six months.
  • To achieve the MNT results, dietitian spent an average of 90 minutes per volunteer during the first three months and 30 minutes in the next three months of therapy
  • Volunteers assigned to MNT were counseled with individuated approaches.
Funding Source:
University/Hospital: Massachusetts General Hospital
Not-for-profit
0
Foundation associated with industry:
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? 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? 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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? No
  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