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MNT: Comparative Effectiveness of MNT Services (2009)

Citation:

Hebert JR, Ebbeling CB, Ockene IS, Ma Y, Rider L, Merriam PA, Ockene JK, Saperia GM. A dietitian-delivered group nutrition program leads to reductions in dietary fat, serum cholesterol, and body weight: the Worcester Area Trial for Counseling in Hyperlipidemia (WATCH). J Am Diet Assoc. 1999; 99(5): 544-552.

PubMed ID: 10333775
 
Study Design:
Retrospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

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

Inclusion Criteria:

Patients of WATCH physicians were invited to enroll as subjects if they:

  • Had appointments to be seen by their physicians during the 24-month recruitment period from January, 1992 to December, 1993
  • Were between the ages of 20 to 65 years
  • Had no prior drug treatment or recent dietitian referral
  • Did not have preexisting coronary heart disease (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.
Exclusion Criteria:

Excluded if not included above.

Description of Study Protocol:

Recruitment

Subjects with hyperlipidemia were recruited from 12 practice sites of the Fallon Clinic.

Design

Retrospective cohort study; the program was implemented as a complement to a randomized physician-delivered intervention. 

Intervention

  • Physicians had already been randomized to usual care, lipid intervention physician training only and lipid intervention physician training plus office support
  • Two individual and two group sessions conducted over six weeks
  • Dietitian-delivered intervention based on patient-centered counseling model.

Statistical Analysis

  • Multiple linear regression was used to evaluate changes in outcome measures
  • Chi-square tests used for categorical variables
  • T-tests used for continuous variables
  • Chi-square tests and one-way ANOVA used to assess baseline differences in categorical and continuous variables among subjects grouped by referral to the dietitian-based program and attendance at the sessions
  • ANCOVA used to evaluate differences in change scores among the dietitian referral groups.
Data Collection Summary:

Timing of Measurements

Measurements made at baseline and after one year.

Dependent Variables

  • Dietary intakes of total and saturated fats and energy, measured through seven-day dietary recall
  • Serum total and LDL-cholesterol levels measured through standard laboratory methods
  • Body weight (beam balance scale), height and body mass index (BMI)
  • Social desirability and social approval measured by Marlowe-Crowne Social Desirability Scale and Martin-Larsen Social Approval Motivation Scale.

Independent Variables

  • Dietitian-based nutrition counseling and education program
  • Two individual sessions and two group sessions over a six-week period.

Control Variables

  • Demographic variables
  • Cigarette smoking
  • Use of exercise to lose weight
  • Motivation to change diet.
Description of Actual Data Sample:
  • Initial N: 1,162 subjects recruited
  • Attrition (final N): 645 had sufficient data for analyses. 558 had never been referred, 44 had attended fewer than three sessions and 43 had attended three or four sessions. 

Age

  • No referral to RD: Mean age 49.5±10.7 years
  • Fewer than three sessions: Mean age 51.9±10.1 years
  • Attended three or four sessions: Mean age 51.6±9.6 years.

Anthropometrics 

Compared with the counterparts with missing data, the subjects with complete data were more likely to be white (95.9% vs. 91.7%, P=0.04), older (49.5±10.7 years vs. 47.8±10.5 years, P=0.07) and less overweight (BMI 28.4±4.9 vs. 29.6±6.1, P=0.001). No differences at baseline between groups in gender, age, marital status, race, employment status or cigarette smoking.

Location

12 sites of the Fallon Clinic in central Massachusetts.

 

Summary of Results:

 

Variables

No Referral - Adjusted Changes

Attended Fewer than Three Sessions - Adjusted Changes

Attended Three or Four Sessions - Adjusted Changes

Total energy (kcals) -145±30 -119±109 -232±111
Total fat (g)

-8.0±1.7

-12.1±6.2

-24.9±6.3

Saturated fat (g) -2.6±0.6 -5.1±2.0 -8.0±2.1, P<0.05
Energy from fat (%) -0.7±0.4 -5.0±1.4, P<0.05 -8.2±1.4, P<0.05
Energy from saturated fat (%) -0.3±0.1 -2.1±0.5, P<0.05 -2.7±0.5, P<0.05
Serum total cholesterol (mmol per L) 0.01±0.03 -0.15±0.12 -0.43±0.13, P<0.05
Serum LDL-cholesterol (mmol per L) -0.02±0.03 -0.13±0.11 -0.48±0.11, P<0.05
Body weight (kg) -1.05±0.23 -2.12±0.75 -4.47±0.88, P<0.05

BMI

-0.38±0.09

-0.77±0.28

-1.56±0.32, P<0.05

Other Findings

After one year, there were significant reductions in outcome measures for subjects attending three or four nutrition sessions vs. subjects attending fewer than three sessions or those never referred to a nutrition session.

Reductions in saturated fat (as percent of energy) were 2.7±0.5%, 2.1±0.5% and 0.3±0.1%, respectively.

These reductions correspond to roughly a 22% relative change from baseline in those attending three or four sessions.

Corollary reductions were observed for total fat (as percent of energy): 8.2±1.4%, 5.0±1.4%, and 0.7±0.4%; LDL-cholesterol:  0.48±0.11mmol per L, 0.13±0.11mmol per L, and 0.02±0.03mmol per L; and body weight: 4.5±0.9kg, 2.1±0.8kg, and 1.1±0.2kg.

The specified changes were additive to those of the physician-delivered intervention. 

Author Conclusion:

This investigation provides empirical data demonstrating the effectiveness of a dietitian-delivered intervention in the care of patients with hyperlipidemia.

Funding Source:
Government: NHLBI
Reviewer Comments:

Incomplete data for almost half of recruited subjects. Significant differences between those with and without complete data. Intervention lasted six weeks, but measurements not made until one year from baseline. Authors note that rate of referral was much lower than anticipated, indicating physician deviation from the algorithm.

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? ???
  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? ???
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.) 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? N/A
  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? Yes
  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? N/A
  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? ???
  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? ???
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? ???
  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? N/A
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