EAL

DLM: Hypertension (2010)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the effects on blood pressure and other cardiovascular risk factors of a comprehensive lifestyle intervention in overweight persons with medication-treated hypertension.

Inclusion Criteria:

Systolic blood pressure (SBP) of 130 to 170mmHg and/or diastolic blood pressure (DBP) of 80 to 100mmHg while taking a stable dose (at least three months) of a single antihypertensive medication or a fixed-dose combination pill
Overweight or obesity (BMI greater than 25kg per m²)
Willingness to accept assignment to both groups
Willingness to complete all intervention and data collection procedures.

Exclusion Criteria:

Active/prior cardiovascular disease
Medication-treated diabetes
Random glucose of greater than 180mg per dL
Renal insufficiency
Fasting cholesterol greater than 260mg per dL
Pregnancy or lactation
Unwillingness to stop all vitamin, mineral or weight loss supplements
Unwillingness to stop antacids containing calcium or magnesium
Consumption of more than 14 alcoholic drinks per week.

Description of Study Protocol:

Screening: Fasting blood specimen, 24-hour urine specimen, fitness test and ambulatory BP monitoring
Randomization: Stratified by race
Nine week study period:
- The lifestyle group was provided a hypocaloric version (500kcal per day less) of DASH diet providing 100mmol per day of sodium and supervised moderate-intensity exercise program for 30 to 45 minutes, three times per week.
- Control group received no intervention
- Weight and medication adherence measured biweekly in all participants, dietary and exercise adherence assessed in daily logs
Last week of follow-up: Fasting blood specimen, 24-hour urine specimen, fitness test and ambulatory BP monitoring.

Data Collection Summary:

Mean 24-hour ambulatory BP was the primary outcome, assessed twice by trained certified technicians using a Space Labs 90207 monitor, after abstinence from exercise for at least 24 hours
Daytime and nighttime BP was the average of measured BPs
Manual BP measured by trained observers using random-zero sphygmomanometers and standard protocol\
Fasting blood specimens measured total and HDL cholesterol, triglycerides and glucose
LDL cholesterol was estimated
Twenty- four-hour urine collections for urinary Na and K excretion used to estimate group dietary compliance
Cardiorespiratory fitness was measured using a submaximal treadmill test
Weight measured by blinded personnel using certified balance-beam scale.

Description of Actual Data Sample:

Of 237 individuals screened, 45 adults were randomized
All 23 subjects in control group completed the study
Of the 22 subjects in the lifestyle group, 20 completed the study (91%)
There were no significant differences between the groups.

Summary of Results:

Forty subjects equally allocated across two groups was estimated to provide 80% power to detect net group differences in BP at a=0.05
Of the 20 subjects in the lifestyle group, study foods were eaten on 97% of the 63 total days and attended 86% of the exercise sessions. Average pill compliance was 98.6% in lifestyle group and 97.5% in control group.
At the end of the intervention, mean net weight loss in the lifestyle group was 4.9kg (P<0.001)
Mean net reductions in 24-hour ambulatory SBP and DBP were 9.5mmHg (P<0.001) and 5.3mmHg (P<0.002), respectively. Corresponding changes in daytime SDP and DBP's were 12.1mmHg (P<0.001) and 6.6mmHg (P<0.001).
The lifestyle group experienced net mean reductions in total cholesterol (-25mg per dL, P<0.001), LDL cholesterol (-18mg per dL, P=0.005) and HDL cholesterol (-4.5mg per dL, P<0.001). There was no significant net change in triglyceride levels (7mg per dL [95% CI: -10 to 24, P=0.43]), TC/HD ratio (-0.23 [95% CI: -0.75 to 0.28, P=0.36]) or fasting glucose (-4mg per dL [95% CI: -15 to 7, P=0.47]).
Work Group Conversion: The lifestyle group experienced net mean reductions in total cholesterol (-0.646mmol per L), LDL cholesterol (-0.465mmol per L) and HDL cholesterol (-0.116mmol per L).

Author Conclusion:

This trial demonstrated that a comprehensive lifestyle intervention can substantially lower BP and improve BP control in hypertensive overweight adults taking one antihypertensive agent
Specifically, the lifestyle intervention reduced mean 24-hour SBP by 9.5mmHg and DBP by 5.3mmHg
Blood pressure reductions of this magnitude are similar to those achieved with pharmacotherapy. Yet in contrast to drug therapy, comprehensive lifestyle changes also resulted in additional benefits beyond blood pressure reduction, that is, favorable effects on weight, fitness and serum total and LDL cholesterol levels.

Funding Source:

Government:

NHLBI and National Center for Research Resources of the NIH

University/Hospital:

Johns Hopkins Medical Institutions; Albert Einstein College of Medical of Yeshiva University

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

Well-designed study with low drop-out rate and high adherence levels
Patient population was demographically heterogeneous, but small sample size does not allow for subgroup analyses on certain characteristics
The duration of the intervention was relatively short at nine weeks.

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?	???
	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?	N/A
	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?	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?	Yes
	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?	Yes
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