Hypertension

HTN: Medical Nutrition Therapy (2015)

Citation:

Applegate WB, Miller ST, Elam JT, Cushman WC, El Derwi D, Brewer A, Graney MJ.  Nonpharmacologic intervention to reduce blood pressure in older patients with mild hypertension. Arch Intern Med. 1992; 152: 1162-1166.

PubMed ID: 1599343
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To determine if nonpharmacologic interventions are effective in older patients with hypertension.

Inclusion Criteria:
  • Men and women aged 60 to 85 years
  • Mild diastolic hypertension, with diastolic blood pressure of 85 to 100mm Hg
  • At least modestly overweight (115% of ideal body weight or greater by 1983 Metropolitan Life Insurance Company tables)
  • Folstein Mini-Mental State score of more than 22 of 30
  • Adequate physical health
  • Adequate vision (20/60 or better)
  • Willingness to participate in the lifestyle interventions, including moderate physical activity and signed informed consent.
Exclusion Criteria:
  • History of myocardial infarction within the past year
  • Previous diagnosis of angina pectoris or congestive heart failure
  • Stroke within the last year
  • Other serious cardiovascular disease
  • Diabetes mellitus
  • Other serious chronic illnesses
  • Random serum glucose concentration of more than 12.2mmol per L
  • Serum creatinine level of more than 150μmol per L
  • Serum cholesterol level of more than 6.85mmol per L
  • Severe physical handicaps
  • Disorders that may interfere with implementation of dietary interventions
  • Use of medications that could affect blood pressure
  • Patients were discontinued from the trial at any point for the following reasons: Systolic blood pressure of more than 199mm Hg or diastolic blood pressure of more than 105mm Hg on two consecutive visits, one to two weeks apart, inability to tolerate intervention due to intolerable side effects, or the patient elected to discontinue participation.
Description of Study Protocol:

Recruitment

Volunteers were recruited from the community by advertising and by using community blood pressure screening programs.

Design

Randomized controlled clinical trial. 

Blinding Used

Certified blood pressure technicians were blinded to group assignment. 

Intervention

  • Experimental arm was a nonpharmacologic intervention combining weight reduction, sodium restriction and increased physical activity, consisting of eight weekly group sessions and two individual sessions during the intensive 10-week phase, followed by four monthly group sessions during the maintenance phase
  • Food records were reviewed each week and returned to participants with suggestions for improvement
  • All intervention sessions were conducted by a Registered Dietitian who had previous experience with conducting group sessions involving weight management and sodium restriction
  • Control group received no treatment during the study.

Statistical Analysis

  • Each response variable was analyzed separately using repeated measures ANOVA with one grouping factor, group assignment, allowing determination of the significance of group effects, time effects and interaction effects
  • All statistical tests were nondirectional
  • Equivalent results were obtained using analysis of absolute values, analysis of change from baseline values or change relative to baseline values (proportion change)
  • For comparisons of baseline characteristics of intervention and control groups, two sample T-tests were used for continuous variables and chi-square tests for categorical variables.
Data Collection Summary:

Timing of Measurements

  • Clinic visits occurred monthly, ending at six months after randomization
  • History and physical exam, weight, blood pressure, blood samples and 24-hour urine samples collected at baseline
  • Blood pressure and weight were measured at each clinic visit
  • 24-hour sodium excretion was measured at baseline and at two, three and six months.

Dependent Variables

  • Blood pressure was assessed by certified technicians using random zero sphygmomanometers
  • Weight
  • 24-hour sodium excretion.

Independent Variables

  • Nonpharmacologic intervention vs. control (no treatment)
  • Diet recalls were used to determine intake.

 

 

Description of Actual Data Sample:
  • Initial N: 56 participants randomized
  • Attrition (final N): 47 completed the trial (84%). 21 in intervention group (12 females, nine males), 26 in control group (14 females, 12 males). Three dropped out of the intervention group prior to the second session, stating they were no longer interested, two (one from each group) were given antihypertensive medications for elevated blood pressure, two from the intervention group were given antihypertensive medications but blood pressure was normal, one from the control group was diagnosed with cancer, one from the intervention group was restarted on antihypertensive medication.
  • Age: Mean age 65±3.8 years in intervention group, mean age 64±4.5 years in control group 
  • Ethnicity: 57% Caucasians in intervention group; 65% Caucasians in control group
  • Anthropometrics: Differences between groups at baseline in diastolic blood pressure (experimental 86±1.7mm Hg vs. 88±3.6mm Hg, P=0.03) and weight (experimental, 89±16.0kg vs. control, 81±11.4kg, P=0.07)
  • Location: Tennessee.

 

Summary of Results:

Blood Pressure Outcomes

Variables

SBP

Experimental (N=21)

SBP

Control (N=26)

DBP

Experimental (N=21)

DBP

Control (N=26)

Baseline

142.6±11.7 144.5±9.7 86.5±1.7 88.4±3.6

One-month change

-1.2

-1.7

-1.7

-1.3

Two-month change -7.6 -4.3 -7.5 -1.7
Three-month change -9.3 -1.5 -5.3 -0.9
Four-month change -11.4 -1.6 -7.4 -0.8
Five-month change -8.2 -3.9 -5.8 -3.7
Six-month change -8.7 -4.5 -6.8 -1.9

Other Findings

Attendance at the intervention sessions was excellent.

The intervention group lost more weight (-2.1kg) over six months than the control group (+0.3kg), P=0.0009.

Trends for decreasing 24-hour urine sodium excretion in both the intervention and control groups, with greater trend in the intervention group, were not statistically significant.

The intervention group experienced more reduction in systolic (P=0.02) and diastolic (P=0.003) blood pressure than did the control group (mean differences between groups at six months, 4.2 vs. 4.9mm Hg, respectively).  

Author Conclusion:

Our data demonstrate that a lifestyle modification program will lower blood pressure levels in older people with borderline or mild elevations of diastolic blood pressure. The participants attended the intervention sessions and were compliant with the interventions. The magnitude and significance of the changes in systolic and diastolic blood pressure in this study make it likely that nonpharmacologic therapy requiring only modest behavior change is both achievable and effective in older patients with hypertension.

Funding Source:
Other: Not reported
Reviewer Comments:

Differences between groups at baseline, but differences in baseline DBP and weight were adjusted for in the analysis. Authors note the following limitations:

  • Small sample size was not large enough to allow analyses by race and gender subgroups 
  • Study involved a volunteer cohort
  • Results may not apply to all older persons, particularly those with multiple co-morbid problems, since those people were excluded from the study.
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? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? ???
  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%.) 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? 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)? N/A
  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? 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