MNT: Effectiveness of MNT for Hypertension (2009)


Pritchard DA, Hyndman J, Taba F. Nutritional counselling in general practice: A cost effective analysis. J Epidemiol Community Health. 1999; 53: 311-316.

PubMed ID: 10396539
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To study the clinical and cost outcomes of providing nutritional counseling to patients with one or more of the following conditions: Overweight, hypertension, and type 2 diabetes. The study also examined whether the outcome and drop-out rate was improved if the general practitioner both invited the patient to participate in nutritional counseling and monitored the patient's progress.

Inclusion Criteria:
  • Patients in a general practice were opportunistically screened and those with pre-existing diagnosis of overweight, hypertension or type 2 diabetes, determined from patient notes
  • Patients without a pre-existing diagnosis recorded in the notes, but who appeared to be overweight on presentation at reception were also invited to participate.
Exclusion Criteria:

Patients were excluded if:

  • Mentally ill
  • Intellectually handicapped
  • Terminally ill
  • Acutely ill
  • Pregnant
  • Participating in other health studies.


Description of Study Protocol:


Consecutive patients at a university group general practice set in a lower socioeconomic outer suburb of Perth, Australia, were screened opportunistically for one or more of the following conditions: Overweight, hypertension, and type 2 diabetes.


Randomized controlled trial: The patients, after screening were randomly allocated to one of two intervention groups (doctor/dietitian or dietitian) or a control group. Both intervention groups received six counseling session over 12 months from a dietitian. The control group received the results of the initial measurements and if they had queries were advised to discuss with the doctor with whom they had made the appointment. No counseling was given by the dietitian. If patients asked questions, the doctor provided usual care, including monitoring, advice and prescriptions, but not referral to the dietitian.

Patients allocated to the dietitian group were invited to participate in the study by the dietitian. In the doctor/dietitian group, it was the doctor who invited the patients to join the study and the same doctor reviewed progress at two of the six counseling sessions.

Blinding Used

Doctors were never informed about who was in the control and dietitian groups.


Two intervention groups: Both intervention groups received six counseling sessions over 12 months from a dietitian. The patients in the doctor/dietitian group saw the doctor at two of the six visits to review progress.

Statistical Analysis

  • An X2 test was used to compare demographic composition of the study groups
  • Confidence intervals for differences in means were used to compare groups with respect to outcome measurements
  • Outcomes were subjected to analysis by intent to treat, which assumed a patient's measurements remained unchanged after a patient dropped out of the study (the patient's last measurement was used to populate all subsequent missing values)
  • Costing was estimated in 1993-1994 dollars.
Data Collection Summary:

Timing of Measurements

For the two intervention groups, six measurements were taken in conjunction with dietitian counseling visit, at baseline and at five other visits spaced equally between initiation and 12 months (end) of study time. For control group, at baseline and at end of 12 months.

 Dependent Variables

  • Weight
  • Blood pressure
  • Glycated hemoglobin
  • Medication use (cardiovascular)
  • Cost effectiveness analysis.

Independent Variables

One of two intervention groups (doctor/dietitian or dietitian) or a control group.



Description of Actual Data Sample:
  • Initial N: 273
  • Attrition (final N): 177 (65% completion)
  • Age: Range, 25 to 65 years. 73% less than 50 years old, no significant difference between intervention and control groups.
  • Other relevant demographics: Male=75, female =198; consistent with the practice's overall attendance pattern. No significant difference between groups for socioeconomic status quartiles.


No significant difference between the three groups in the frequency of diagnosis. Overweight accounted for 62% of patients, 31% had overweight and hypertension, 2% were overweight and diabetic, 4% had all three conditions, and remaining 1% had either diabetes or hypertension.


Perth, Australia, university general practice group setting.

Summary of Results:

Comparison of control and interventions groups showing the average final measurement and its percentages change from screening for all patients with each condition, patients completing all sessions and drop-outs. 

Control Mean
Control Percentage Change
Control N
Doctor Dietitian Mean
Doctor Dietitian Percentage Change
Doctor Dietitian N
Dietitian Mean
Dietitian Percentage Change
Dietitian N
All patients
85.0 kg
Hypertension All patients 
112mm Hg
102mm Hg
104mm Hg
112mm Hg
100 mm Hg
98mm Hg
113 mm Hg
108mm Hg
109 mm Hg
Type 2 Diabetes (Percentage Glycated hgb)
All patients

Other Findings

  • Both intervention groups reduced weight and blood pressure compared with the control group
  • The dropout rate of overweight patients in the dietitian group (45%) was significantly greater than the 29% for both the doctor/dietitian group
  • For overweight patients who were not hypertensive, 63% of control, 70% of doctor/dietitian, and 59% of dietitian patients attended all sessions
  • There was no difference between the control and doctor/dietitian groups with respect to the proportion of hypertensive patients who attended all sessions
  • No significant difference was found between control and intervention groups for diabetes by intention to treat analysis
  • No significant difference was found in the average defined daily dose of cardiovascular drug use by patients in the three groups on recruitment or at the final counseling session
  • Cost-effectiveness of weight loss: Compared with the control group, the cost of an extra kg of weight loss for the doctor/dietitian group was $9.76 and for the dietitian group was $7.30
  • Compared with commercial, balanced nutrition weight reduction programs, weight loss was achieved at considerably less cost in both of this study's intervention groups. The associated decreases in blood pressure were achieved at no further cost and without recourse to increased medication.
Author Conclusion:
  • This study indicates that general practice can provide health promotion to improve overweight and hypertension at a reasonable cost, over a 12-month period, with a combination of the skills of the dietitian and the patient's general partitioner. The general practitioner's contribution increases the cost of the health promotion, but leads to fewer dropouts from the programme and outcomes better than those achieved by the dietitian alone.
  • Patients in the doctor/dietitian groups were more likely to complete the program than those in the dietitian group.
Funding Source:
Foundation associated with industry:
Reviewer Comments:
  • Cost was only considered with weight loss. Large dropout rate.
  • There was considerable discussion about related studies of cost and services.
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.) 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? ???
  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? ???
  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? ???
  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)? N/A
  8.6. Was clinical significance as well as statistical significance reported? ???
  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