EAL

MNT: Effectiveness of MNT for Hypertension (2009)

Citation:

Ramsay LE, Ramsay MH, Hettiarachchi J, Davies DL, Winchester J. Weight reduction in a blood pressure clinic. British Medical Journal. 1978; 2: 244-245.

PubMed ID: 678886

Study Design:

Randomized clinical trial.

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To compare the efficacy of methods used by individual doctors in the Glasgow Blood Pressure Clinic, including referral to the hospital dietitian, giving the patient a fact sheet or simply advising the patient to lose weight.

Inclusion Criteria:

Hypertensive patients attending the Glasgow Blood Pressure Clinic
Overweight (on clinical judgment)
Had not attended a dietitian within six months
Did not need a specific diet, such as for diabetes.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Patients attending the Glasgow Blood Pressure Clinic.

Design

Randomized clinical trial.

Blinding Used

In two-thirds of patients, readings were made by a trained nurse who was unaware of the study.

Intervention

Four clinicians agreed to randomly allocate subjects to one of three strategies for attaining weight reduction and were followed for one year:

Advice only: Doctor asked the patient to lose weight, giving whatever advice and encouragement he wanted
Diet sheet: Doctor instructed patient on how to use the diet sheet, 800kcal diet promoted on sheet
Referral to a dietitian: Referred to the hospital dietitian requesting that an 800kcal weight reduction diet be prescribed. Methods used and follow-up in the dietetic clinic were left entirely to the discretion of the dietitians, who were not aware of this study.

Statistical Analysis

Results were analyzed with Mann-Whitney U-test for comparison of means and the Spearman rank coefficient for correlations
Significance levels are for two-tailed tests.

Data Collection Summary:

Timing of Measurements

Management during the year of follow-up was entirely routine. Initial weight, blood pressure and treatment were recorded upon randomization, and endpoint data at the attendance nearest to one year after randomization within nine to 15 months.

Dependent Variables

Weight was measured routinely in clinics after outdoor clothing had been removed
Blood pressure measured with a standard cuff and sphygmomanometer
Average body weight for sex, height and age was obtained from tables of the Society of Actuaries Build and Blood Pressure Study.

Independent Variables

Advice only
Diet sheet
Referral to a dietitian.

Description of Actual Data Sample:

Initial N: 67 originally included in study
Attrition (final N): 49 subjects (73% completion). 20 in advice only, 14 in diet sheet, and 15 in dietitian groups. Seven subjects defaulted, two were discharged and nine had no examination at nine to 15 months.
Anthropometrics: The three treatment groups did not differ significantly in sex, age, weight, height, percentage weight above average, number of patients lost from the study or duration of follow-up. However, patients in the advice only group had a higher mean diastolic blood pressure than the others, and a higher systolic blood pressure than those referred to the dietitian (all P<0.05).
Location: Glasgow.

Summary of Results:

Changes in the Three Treatment Groups After One Year After Randomization

Variables	Advice Only (N=20)	Diet Sheet (N=14)	Dietitian (N=15)
Duration of follow-up (months)	12.7	12.4	12.9
Weight change (kg)	-2.15	-2.64	-5.10, P<0.05 vs. Advice Only
Change in SBP (mm Hg)	-11.2	-5.7	-11.9
Change in DBP (mm Hg)	-5.3	-3.0	-6.9
Treatment increased	10	1	3
Treatment decreased	3	1	2
Change in number of drugs per patient	+0.35	-0.14	+0.08

Other Findings

Weight fell by a mean of 3.2kg in all 49 patients.

Those referred to a dietitian lost more weight (mean 5.1kg) than those given a diet sheet (mean 2.64kg) or simply advised by the doctor to reduce weight (mean 2.15kg).

One-third of all patients lost 6.0kg or more.

Changes in blood pressure over the year were not significantly different in the three groups, but anti-hypertensive treatment was increased more often in those given advice only.

Author Conclusion:

Successful weight loss was associated with a highly significant and substantial improvement in blood pressure control and with less frequent increases in anti-hypertensive treatment.

Funding Source:

Other:

Not reported

Reviewer Comments:

Small numbers of subjects in groups, only 73% completion. Significant differences between groups at baseline. Methods used and follow-up in the dietetic clinic were left entirely to the discretion of the dietitians, who were not aware of this study. Authors note that the results did not provide direct evidence that intervention by a dietitian improved blood pressure control, largely because of a chance mismatching of the groups as regards initial blood pressure.

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?	No
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		No
	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?	No
	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?		???
	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?	???
	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?	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?		???
	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?	???
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	???
	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)?	N/A
	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?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
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