• Increase Font Size
  • Decrease Font Size
  • View as PDF

HTN: Medical Nutrition Therapy (2015)

Citation:

Rankins JR, Sampson W, Brown B, Jenkins-Salley T. Dietary Approaches to Stop Hypertension (DASH) intervention reduces blood pressure among hypertensive African American patients in a neighborhood health care center. J Nutr Educ Behav. 2005; 37: 259-264.

PubMed ID: 16053815
 
Study Design:
Non-Randomized Controlled Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To test the efficacy of the DASH-Dinner with Your Nutritionist program with poorly controlled hypertensive, low-income African American adults in a university-neighborhood health center setting.

Inclusion Criteria:
  • African American ancestry
  • Ages 45 years to 65 years
  • Systolic blood pressure (SBP) measuring above 140mm HG and diastolic blood pressure (DBP) above 90mm HG on average for last three clinic visits
  • Prescribed antihypertensive medication.
Exclusion Criteria:
  • Terminally ill
  • Mentally ill
  • Diagnosis of end-stage renal disease
  • Reported excessive alcohol consumption (more than 14 alcoholic beverages per week)
Description of Study Protocol:

Recruitment

Patients with a medical diagnosis code for hypertension from one university neighborhood health care clinic were computer generated and compared with the inclusion and exclusion criteria. All eligible participants had given informed consent and entered the study.

Design

Non-randomized trial.

Intervention
  • Six groups of 12 patients to 15 patients and a guest of their choice were given the weekly intervention program of 1.5-hour to two-hour session in each of eight consecutive weeks. The nutritionist supervised program outline:
    • BP and weight monitoring by a clinic nurse: 20 minutes to 25 minutes
    • Nutrition education PowerPoint by nutritionist: 25 minutes to 30 minutes
    • Meal service and "table talk": 30 minutes to 40 minutes
    • Recipe demonstrations and taste-testing by nutritionist: 20 minutes to 25 minutes.
  • Weekly programs used principles of Social Cognitive Therapy.

Statistical Analysis

  • All study participants were divided into four groups based on the number of sessions attended.
    • G1 (N=32): Missed no more than two of eight DASH-Dinners
    • G2 (N=12): Missed three or four of eight DASH-Dinners
    • G3 (N=20): Missed five to seven of eight DASH-Dinners
    • G4 (N=18): Missed all eight DASH-Dinners
  • Statistical outcomes used within-group repeated measures (baseline and post-intervention) for both BP measurements and serum folate.
Data Collection Summary:

Timing of Measurements

BP and serum folate were measured at baseline and after the eight-week intervention.

BP:

  • Initial BP was the average of the last three clinic visit BP measures prior to the study
  • Post-BP was the average of two BP measures taken during clinic visit and within 30 days after the study ended.

Folate: Fasting samples of initial and post-serum folates were drawn just prior to and within 30 days after the study ended.

Dependent Variables

  • SBP
  • DBP.

Independent Variables

Dietary intervention.

Control Variables

Attendance at sessions.

 

Description of Actual Data Sample:
  • Initial N: N=82
  • Attrition (final N): N=82
  • Age: 55.2±6.1 years
  • Ethnicity: African American
  • Other relevant demographics: Low income.

Anthropometrics

  • BP (mm Hg):
    • Systolic: 147.6±15.1
    • Diastolic: 90.0±12.0
  • BMI (kg/m2: 34.0±8.3
  • Weight (kg): 93.5±21.2kg
  • Mean body mass index (BMI) was significantly higher than the mean BMI for G2 and G3 (P<0.01).

Location

United States, University-neighborhood health care center.

Summary of Results:

 

Key Findings

Comparisons

G1
(N=32)

G2
(N=12)

G3
(N=20)

G4
(N=18)
Systolic BP, T1 151.0±15.5** 148.0±11.4 140.3±21.0 148.4±12.7
Systolic BP, T2

142.6±10.2**

(N=32)

148.7±15.5

(N=11)

140.9±24.4

(N=12)

146.4±22.4

(N=16)
Diastolic BP, T1 90.0±11.7* 86.5±11.4 83.8±9.6 93.3±14.1
Diastolic BP, T2

85.7±8.4*

(N=32)

85.4±10.7

(N=11)

84.0±10.3

(N=12)

89.0±15.9

(N=16)
Serum Folate, T1 17.1±3.7* Too small N to report Too small N to report Too small N to report
Serum Folate, T2 18.8±3.4 Too small N to report Too small N to report Too small N to report

* P<0.05

** P<0.01

  • For G1, both the mean systolic and diastolic blood pressures decreased significantly (P<0.01 and P<0.05, respectively) between pre-measurement and post-measurements
  • For G1, serum folate also increased significantly (P<0.05) between pre-measurements and post-measurements
  • Serum folate pre-measurement and post-measurements were not reported in any other group due to small sample size.
Author Conclusion:

Regular participation (missing no more than two of eight sessions) in the DASH-Dinner intervention significantly lowered both systolic blood pressure and diastolic blood pressure in low-income hypertensive African Americans in a university-neighborhood health center setting.

Funding Source:
Not-for-profit
Women and Minorities Access to Research grant from the American Heart Association
Other non-profit:
Reviewer Comments:
  • Small number of participants in sub-groupings limits ability to find statistical differences
  •  Participants choose to be included in the study, which may have an influence on motivation of participants
  •  Unclear when the three blood pressure measurements used for the initial BP average were taken prior to the study 
  • Attrition at follow-up for G2, G3, and G4 was not described, yet it significantly affected the ability to report pre-intervention and post-intervention on the secondary outcome (serum folate)
  • Other factors that could have affected BP during the eight-week study intervention were not reported, specifically any changes in BP medication or dosage.
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? 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? N/A
  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? No
  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? No
  4.4. Were reasons for withdrawals similar across groups? N/A
  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? Yes
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? 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? 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? 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)? 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? 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