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MNT: Weight Management (2015)


Bradley DW, Murphy G, Snetselaar LG, Myers EF, Qualls LG. The incremental value of medical nutrition therapy in weight management. Manag Care Langhorne Pa. 2013; 22(1): 40-45.

PubMed ID: 23373140
Study Design:
Case Control Study
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To evaluate the incremental cost of, and health benefits attributable to, medical nutrition therapy (MNT) for individuals participating in the Member Health Partnership (MHP) program.
Inclusion Criteria:
  • Overweight or obese individuals
  • Age 18 years or older
  • Enrolled in the MHP program between January 2006 and May 2008
  • Provided information on whether they had diabetes or hypertension.
Exclusion Criteria:
  • Pregnant
  • Had outpatient renal dialysis
  • Had bariatric surgery
  • Treated for cancer.
Description of Study Protocol:


  • No recruitment details were provided
  • Data was collected by Blue Cross/Blue Shield of North Carolina (BCBSNC) through standard quality improvement business processes that did not require approval by an Institutional Review Board (IRB).


Two-year, retrospective, case-control study.


Cases were divided into two groups (MNT vs. no MNT):

  • MNT group: All eligible study participants who received MNT within four weeks of enrolling in the MHP program (specifics of MNT was not provided)
  • No MNT (control group):
    • Created by matching each individual in the MNT group with up to 10 eligible study participants who did not choose to receive MNT
    • Matching was conducted using propensity scores that required an exact match on gender, obesity category, diabetes status and hypertension status, and the closest possible match on age, rage, smoking status, coronary artery disease status and hyperlipidemia status.

Statistical Analysis

  • Data were analyzed using PC SAS version 9.1.3
  • A result was considered to be statistically significant if the observed significance level (P-value) was less than 0.05
  • Study participants who had missing or invalid responses for weight, BMI or waist circumference on either survey were excluded from the outcomes analysis of that parameter
  • Thresholds for valid responses were established based on the empirical experience of the authors and RDs
  • Within-group differences were analyzed using paired T-tests for quantitative variables and the McNemar test for categorical variables
  • Between-group differences were analyzed using ordinary least squares regression for quantitative variables, logistic regression for categorical variables and repeated measures ANOVA with between-subjects factors for the proportion of individuals who exercised at least three days a week
  • Covariates were included in the between-group comparisons to control for clinically relevant differences between the groups
  • Gender, diabetes, hypertension and the time between surveys were included in all comparisons, and the regression models also included the value of the dependent variable at baseline.
Data Collection Summary:

Timing of Measurements

  • Baseline data  were obtained from the MHP program enrollment survey, and follow-up data were obtained from a survey administered approximately two years after program enrollment
  • The mean time between surveys was 20.3 months and was slightly longer among MNTs than no MNTs (21.6 months vs. 20.0 months).

Dependent Variables

  • Self-reported responses to survey questions collected data on changes in:
    • Weight: Clinically significant weight loss defined as at least a 5% decrease in weight
    • Body mass index (BMI)
    • Waist circumference: Clinically significant change in waist circumference was defined as a reduction from a high-risk waist circumference [more than 102cm (40 inches) for men and more than 88cm (35 inches) for women] to a waist circumference below those thresholds
    • Physical exercise: It is considered clinically significant if the participant exercised at least three days per week  for at least 30 minutes doing moderate to vigorous activity.
  •   Utilization and cost of the MNT benefit:
    • MNT claims and membership data were extracted from Blue Cross/Blue Shield of North Carolina's (BCBSNC) database
    • MNT claims data were restricted to allowed claims incurred by MHP program participants, and we measured the total allowed cost including member liability
    • The utilization and cost metrics were the percentage of MHP program participants who used the MNT benefit, the number of MNT claims per user and the MNT claims cost per member per month (PMPM)
    • Member months were calculated by summing the number of members in each measurement month, and PMPM costs were calculated by dividing total costs by total member months.

Independent Variables

Group: MNT vs. no MNT.

Description of Actual Data Sample:

Initial N

Baseline measurement data: N=838 MNTs, 3,103 no MNTs.

Attrition (Final N)

Follow-up survey response rate was 34.7% MNT and 35.6% no MNT.

Characteristic MNT Group (N=291) No MNT Group (N=1,104)
Female 74.6% (217 of 291) 75.7% (836 of 1,104)


Characteristic MNT Group (N=291) No MNT Group (N=1,104)
Age category
Less than 35 years
10.0% (29 of 291) 11.6% (128 of 1,104)
Between 35 years and 44 years
24.4% (71 of 291) 25.9% (286 of 1,104)
Between 45 years and 54 years
36.1% (105 of 291) 35.3% (390 of 1,104)
55 years and above
29.6% (86 of 291) 27.2% (300 of 1,104)


Characteristic MNT Group (N=291) No MNT Group (N=1,104)
20.8% (56 of 269) 19.7% (200 of 1,013)
77.3% (208 of 269) 77.3% (783 of 1,013)
1.9% (5 of 269) 3.0% (30 of 1,013)

Other Relevant Demographics

Characteristic MNT Group (N=291) No MNT Group (N=1,104)
Smoking prevalence 6.9% (20 of 291) 6.4% (71 of 1,104)
Prevalence of medical conditions
19.2% (56 of 291) 15.9% (175 of 1,104)
37.8% (110 of 291) 40.4% (446 of 1,104)
40.8% (117 of 287) 40.4% (446 of 1,104)
Coronary artery disease
2.8% (8 of 289) 2.6% (29 of 1,104)


Characteristic MNT Group (N=291) No MNT Group (N=1,104)
Weight, mean (SD), kg 94.4 (20.5) 95.2 (21.8)
Body mass index, mean (SD) 33.4 (5.9 34.1 (6.9)
Obesity category
Pre-obese (BMI 25.0 to 29.9)
32.3% (94 of 291) 30.3% (334 of 1,104)
Obese Class 1 (BMI 30.0 to 34.9)
36.1% (105 of 291) 34.5% (381 of 1,104)
Obese Class 2 (BMI 35.0 to 39.9)
16.5% (48 of 291) 16.4% (181 of 1,104)
Obese Class 3 (BMI 40.0 or higher)
15.1% (44 of 291) 18.8% (208 of 1,104)
Waist circumference, mean (SD), cm 102.5 (14.4) (N=160) 101.3 (14.4) (N=607)
Exercise 30 minutes a day at least three times a week 46.9% (136 of 290) 43.1% (471 of 1,094)


North Carolina.

Summary of Results:

Key Findings

Within-group Results for Pre-Post Health Outcomes
Parameter Group Baseline Follow-up Difference Heading P-Value
Weight, mean (SD), kg MNT 94.0 (20.4) 90.9 (21.2) -3.1 (10.6) T(278) = -4.9 <0.001
No MNT 94.6 (21.1) 93.1 (21.9) -1.4 (12.3) T(1051) = -3.7 <0.001
Body mass index, mean (SD) MNT 33.4 (6.0) 32.3 (6.3) -1.1 (3.8) T(278) = -4.9 <0.001
No MNT 33.9 (6.6) 33.5 (6.9) -0.4(4.3) T(1041) = -2.9 0.004
Waist circumference, mean (SD), cm MNT 103.3 (14.1) 100.4 (13.1) -2.9 T(134) = -2.8 0.006
No MNT 101.4 (14.2) 100.2 (14.1) -1.1 T(501) = -2.1 0.034
Exercise 30 minutes a day at least three times a week, percent (N) MNT 47.2% (135 of 286) 64.0% (183 of 286) 16.8 percentage points S(1) = 21.3 <0.001
No MNT 43.1% (465 of 1,078) 52.5% (566 of 1,078) 9.4 percentage points S(1) = 27.3 <0.001


Between-group Difference in Pre-Post Health Outcomes
Outcome MNT Group No MNT Group Unadjusted Group Difference Adjusted Group Difference P-Value
Change in the mean weight (kg), baseline to follow-up -3.1 -1.4 -1.7 Beta = -1.75, T(1,314) = -2.21 0.028
Change in mean BMI, baseline to follow-up -1.1 -0.4 -0.7 Beta = 0.79, T(1,314) = -2.88 0.004
Change in mean waist circumference (cm), baseline to follow-up -2.9 -1.1 -1.8 No difference 7.05
Percentage point increase between baseline and follow-up in exercise 30 minutes a day at least three times a week 16.8 9.4 7.4 F(11,358) = 4.07 0.044



Within-group and Between-group Results for Clinically Significant Health Outcomes
Outcome MNT No MNT Group Difference Adjusted OR (95% CI) P-Value
Maintained or lost weight (N) 66.3% (185 of 279) 57.5% (605 of 1,052) 8.8 percentage points 1.5 (-1.2 to 2.0) 0.003
Achieved clinically significant reduction in weight (N) 39.8% (111 of 279) 24.0% (253 of 1,052) 5.8 percentage points 2.2 (-1.7 to 2.9) ≤0.001
Achieved clinically significant reduction in waist circumference (N) 16.7% (15 of 90) 17.8% (57 of 320) -1.1 percentage points No difference >0.1

Other Findings

  • Within-group results for pre-post health outcomes: Both groups achieved statistically significant improvements in weight, BMI, waist circumference and exercise frequency between baseline and follow-up.
  • Between-group differences in pre-post health outcomes:
    • After controlling for clinically relevant baseline characteristics, and measurement time, MNTs experienced greater decreases in weight and BMI than no MNTs
    • There was no difference between the groups in waist circumference
    • The increase in the proportion of individuals who exercise regularly was statistically significantly higher among MNTs (16.8 percentage points) than no MNTs (9.4 percentage points).
  • Within-group and between-group results for clinically significant health outcomes:
    • The percentage of study participants who maintained or lost weight was higher among MNTs than no MNTs, at 66.3% and 57.5%, respectively
    • After controlling for group differences in clinically relevant baseline characteristics and measurement time, MNTs had 1.5 times the odds of maintaining or losing weight than did no MNTs
    • The percentage of individuals who achieved a clinically significant reduction in weight was higher among MNTs (39.8%) than no MNTs (24.0%), with MNTs having twice the odds of achieving this outcome compared with no MNTs
    • The percentage of participants who achieved clinically significant reduction in waist circumference was similar for both groups, at 16.7% for MNTs and 17.8% for no MNTs, and the difference between groups was not statistically significant.
  • Utilization and cost of the MNT benefit:
    • Between January 2006 and May 2008, 109,226 individuals participated in the MHP program
    • Of these participants, 5.0% (5,504 of 109,226) utilized the MNT benefit
    • The average number of MNT visits among these individuals was 2.6
    • Slightly less than half of the individuals (45.2%) used only one visit, while 20.7% used two visits and 34.1% used three or more visits
    • Utilization among the subset of the population who were in the MNT group for the health outcomes analysis was slightly higher than for the overall population, averaging 3.9 visits
    • The cost of the MNT benefit was $0.03 per member per month (PMPM).
Author Conclusion:
  • This research translates previous research from randomized controlled trials showing that MNT provides patient benefits into application in practice, and it is the first published study that evaluates a policy decision by an insurance company to provide coverage for MNT
  • The current study provides encouraging results that MNT is a valuable adjunct to health management programs that can be implemented for a relatively low cost. MNT warrants serious consideration as a standard inclusion in health benefit plans.
Funding Source:
Other: not described
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? ???
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.) N/A
  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%.) ???
  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? N/A
  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.) N/A
  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? N/A
  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? No
  6.6. Were extra or unplanned treatments described? No
  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? No
  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)? 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? 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? ???
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? ???