HTN: Medical Nutrition Therapy (2015)
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
To determine the effect on blood pressure of two multi-component, behavioral interventions.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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).
- 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.
- 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
|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|
|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|