DLM: Medical Nutrition Therapy (2010)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To assess the effectiveness of a dietitian-based nutrition counseling and education program for patients with hyperlipidemia.

Inclusion Criteria:
  • Had appointments to be seen by their physicians during the 24-month recruitment period from January 1992 through December 1993
  • Were between the ages of 20 and 65 years
  • Had no prior drug treatment or recent dietitian referral
  • Did not have pre-existing CHD
  • Had a total serum cholesterol level in the upper quartile of the age-, gender- and seasonally adjusted distribution on the basis of the mean of two successive fingersticks during a screening visit
  • Patients at or above the 90th percentile for LDL-C value in the population from which WATCH subjects were recruited (i.e., the upper 40% of WATCH subjects) should receive physician counseling and immediate referral to a registered dietitian (RD).

 

 

Exclusion Criteria:

Did not meet inclusion criteria.

Description of Study Protocol:

Recruitment

Patients referred to RDs had an individual visit followed by two group education sessions and then a final individual visit to the dietitian.

Design

Cohort study

  • Physicians associated with an HMO were randomly assigned to one of three groups
    • 1) MD usual care, 2) MD trained in lipid intervention or 3) MD trained in lipid intervention plus office support. Patients received a referral to the RD when LDL-cholesterol was greater than the 90th percentile for patients in the study (about upper 40% of patients). Those patients who did not meet the 90th percentile criteria for immediate referral to the RD were re-evaluated for serum lipids by their physicians after three months. If LDL-cholesterol remained above NCEP guideline, the patient then received referral to a dietitian.
  • Data were analyzed by number of dietitian sessions: None, attended fewer than three, or attended three or four.

Intervention

Medical Nutrition Therapy

Statistical Analysis

  • X2 test for categorical variables
  • T-tests for continuous variables within groups
  • One-way ANOVA to test for differences between groups 
  • Analysis of covariance
  • Multiple regression to adjust for physician condition.

 

Data Collection Summary:

Timing of Measurements

  • Baseline: Questionnaire to assess demographic variables, smoking, exercise, motivation to change diet at baseline
  • Baseline and one year: Serum lipids, dietary intakes of total and saturated fats, body weight.

Dependent Variables

  • Serum lipid levels including total cholesterol, LDL-cholesterol
  • Body weight
  • Dietary intake.

Independent Variables

Number of MNT sessions attended


 

Description of Actual Data Sample:
  • Total N: 645 categorized into three cohorts: 558 no RD referral; 44 attended one or two sessions; 43 attended three or four sessions
  • Anthropometrics: No significant differences in cohorts at baseline
  • Demographics: Subjects who had attended college were less likely to receive referral to RD (P=0.04)
  • Location: Massachusetts.
Summary of Results:

 

Adjusted Changes by Number of MNT Sessions
Outcome No RD Referral One to Two MNT Sessions Three to Four MNT Sessions
Dietary change (N=645)
Total energy (kcal) -145±30  -119±109 -232±111
Energy from fat (g) -8.0±1.7  -12.1±6.2 -24.9±6.3
Total saturated fat (g) -2.6±0.6  -5.1±2.0 -8.0±2.1a 
Energy from fat (percent) -0.7±0.4  -5.0±1.4a -8.2±2.4a 
Energy from saturated fat (percent) -0.3±0.1 -2.1±0.5 -2.7±0.5a 
Serum lipids change (N=555) 
Total cholesterol (mmol/L)

 0.01±0.03

 0.15±0.12  -0.43±0.13a
LDL-cholesterol (mmol/L) -0.02±0.03  -0.13±0.11  -0.48±0.11ab
Body weight change (N=404)   
Body weight (kg) -1.05±0.23  -2.12±0.75  -4.47±0.88ab
BMI (kg/m2) -0.38±0.09  -0.77±0.28  -1.56±0.32a

a Significantly different from patients never referred

b Significantly different from patients who attended fewer than three sessions

Other Findings

Using an expanded data set of using results from all participants for whom paired data on serum lipids (N=893) and body weight (N=539) were available, reductions were greatest for patients who attended three or more MNT sessions.

  • Total serum cholesterol: -0.37±0.11mmol/L (P<0.001)
  • LDL-cholesterol: -0.40±0.10mmol/L (P<0.0001)
  • Weight: -3.1±0.9kg (P<0.003).
Author Conclusion:

Dietitian-delivered intervention is effective for patients with hyperlipidemia.

Funding Source:
Government: NHLBI RO1 grant
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? ???
  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? Yes
  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.) Yes
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? Yes
4. Was method of handling withdrawals described? ???
  4.1. Were follow-up methods described and the same for all groups? ???
  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%.) ???
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? ???
  4.4. Were reasons for withdrawals similar across groups? ???
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? ???
5. Was blinding used to prevent introduction of bias? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  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.) ???
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? ???
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? ???
  5.5. In diagnostic study, were test results blinded to patient history and other test results? ???
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? N/A
  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? Yes
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)? ???
  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? ???
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