Hypertension

HTN: Medical Nutrition Therapy (2015)

Citation:

Appel LJ, Champagne CM, Harsha DW, Cooper LS, Obarzanek E, Elmer PJ, Stevens VJ, Vollmer WM, Lin PH, Svetkey LP, Stedman SW, Young DR; Writing Group of the PREMIER Collaborative Research Group. Effects of comprehensive lifestyle modification on blood pressure control: Main results of the PREMIER Clinical Trial. JAMA 2003 Apr 23-30; 289 (16): 2,083-2,093. 

PubMed ID: 12709466
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To determine the effect on blood pressure of two multi-component, behavioral interventions.

 

Inclusion Criteria:
  • Not taking anti-hypertensive medication and had a systolic blood pressure of 120 to 159mmHg and diastolic blood pressure of 80 to 95mmHg
  • Non-hypertensive individuals with systolic blood pressure (SBP) of 120 to 139mmHg and diastolic blood pressure (DBP) of 80 to 89mmHg
  • Individuals with stage one HTN with SBP of 140 to 159mmHg and DBP of 90 to 95mmHg
  • At least 25 years old
  • BMI of 18.5 to 45kg per m2.

 

.

Exclusion Criteria:
  • Regular use of drugs affecting blood pressure
  • JNC-VI risk category C (target organ damage or diabetes)
  • Use of weight loss medications
  • Prior cardiovascular event
  • CHF, angina, cancer diagnosis or treatment in past two years
  • Consumption of more than 21 alcoholic drinks per week
  • Pregnancy or lactation 
  • Vitamin and mineral supplement use was not an exclusion.

 

Description of Study Protocol:
  • Screening: Baseline blood pressure data collected at three screening visits, as well as all measurements obtained at baseline
  • Randomization: Randomly assigned to one of three groups: “advice only” comparison group, “established” behavioral intervention (traditional lifestyle recommendations) and “established plus DASH” behavioral intervention (traditional lifestyle recommendations plus DASH diet)
  • Initial six months: 
    • 18 face-to-face intervention contacts (14 group meetings and four individual counselings) kept food diaries, recorded physical activity and monitored calorie and sodium intake
    • Subjects in “established plus DASH” also monitored intake of fruits, vegetables, dairy products and fat intake
    • Blood pressure measured at three months and six months
    • All measurements obtained at six months.
  • Intervention programs lasted 18 months.

 

 

Data Collection Summary:
  • Primary outcome was change in SBP after six months
  • HTN status and DBP at six months were secondary outcomes
  • Blood pressure measurements obtained by trained certified individuals with random-zero sphygmomanometer
  • Weight measured using calibrated scale and height with wall-mounted stadiometer
  • Other data collected at baseline and at six months include Rose Angina questionnaire, medication questionnaire, symptoms/adverse effects questionnaire, 24-hour urine collections for Na, K, P and urea N, submaximal treadmill tests, waist circumference, 24-hour dietary recalls, fasting blood analysis and seven-day physical activity recalls.
Description of Actual Data Sample:
  • Of 3,964 individuals screened, 810 were randomized. All 273 in the “advice only” group, 268 in the “established” group and 269 in the “established plus DASH” group completed the study. 
  • Mean age was 50 years, 62% women, 34% African Americans
  • Baseline characteristics were similar in the randomized groups. Mean SBP was 134.9±9.6mmHg and DBP was 84.8±4.2mmHg. 
  • Among the 38% of participants with HTN, mean SBP was 143.9±7.6mmHg, DBP was 87.5±4.3mmHg. Non-hypertension participants had SBP of 129.5±5.8mmHg and DBP of 83.2±3.1mmHg.

 

Summary of Results:
  • Based on planned sample size of 800 (267 per group), the study had 90% power to detect pairwise between-group differences in SBP of 1.6 to 1.8mmHg in the whole sample, 3.2 to 3.6mmHg among hypertensive participants and 1.7 to 1.9mmHg among non-hypertensive participants
  • Of 18 intervention sessions offered during initial six months, 70% of participants in the established group attended at least 15 sessions; just 8% attended five sessions or less. In the established plus DASH group, 78% attended at least 15 sessions and 7% attended five sessions or less. 
  • Both behavioral interventions significantly reduced weight, improved fitness and lowered sodium intake. The “established plus DASH” intervention also increased fruit, vegetable and dairy intake. 
  • Across the groups, gradients in blood pressure and hypertensive status were evident. After subtracting change in “advice only,” the mean net reduction in SBP was 3.7mmHg (P<0.001) in the established group and 4.3mmHg (P<0.001) in the established plus DASH group. The SBP difference between the established and established plus DASH groups was 0.6mmHg (P=0.43). 
  • Compared with the baseline HTN prevalence of 38%, the prevalence at six months was 26% in the advice only group, 17% in the established group (P=0.01 compared with the advice only group) and 12% in the established plus DASH group (P<0.001 compared with the advice only group, P=0.12 compared with the established group). 
  • The prevalence of optimal blood pressure was 19% in the advice only group, 30% in the established group (P=0.005 compared with the advice only group) and 35% in the established plus DASH group (P<0.001) compared with the advice only group, (P=0.24 compared with the established group). 

 

Author Conclusion:
  • The PREMIER trial documented that individuals with above-optimal blood pressure, including stage one HTN, can make multiple lifestyle changes that lower blood pressure and control HTN
  • In summary, our trial results demonstrate the feasibility of comprehensive behavioral interventions and their beneficial effects on blood pressure and HTN control. Benefits extend to both non-hypertensive individuals at risk for developing HTN and hypertensive individuals who are not receiving medication therapy.

 

Funding Source:
Government: NIH U01HL605701
Reviewer Comments:
  • Well designed study with most subjects available for measurements and high adherence levels
  • Trial participants were demographically heterogeneous; trial results should be applicable to a large portion of US population.
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? 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? 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? 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? 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? Yes
  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)? Yes
  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