Hypertension

HTN: Medical Nutrition Therapy (2015)

Citation:

Eriksson KM, Westborg CJ, Eliasson MCE. A randomized trial of lifestyle intervention in primary healthcare for the modification of cardiovascular risk factors. The Bjorknas study. Scand J Public Health. 2006; 34(5): 453-461. 

PubMed ID: 16990155
 
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 evaluate the feasibility and the effects on cardiovascular risk factors, physical activity and quality of life of a lifestyle intervention program consisting of supervised endurance and circuit training, diet counseling and regular follow-up meetings for high-risk patients in primary care.

Inclusion Criteria:
  • Men and women aged 18 to 65 years
  • Diagnosis of hypertension, dyslipidemia, type 2 diabetes, obesity or any combination thereof. 
Exclusion Criteria:

Subjects with a diagnosis of coronary heart disease, stroke, transient ischemic attacks (TIA), blood pressure more than 180 over 105mm Hg, dementia or severe psychiatric disease.

Description of Study Protocol:

Recruitment

Subjects were selected from the catchment population of the Bjorknas primary healthcare centre in Boden, Sweden. Potential participants were identified by computerized case records because the healthcare centre has no specific screening program. 340 met inclusion criteria and received an invitation by letter. 52% gave written consent to participate.

Design

Randomized controlled parallel group trial with one-year follow-up. Subjects were randomized by computer-generated random numbers kept in sealed, opaque envelopes opened at the healthcare centre after the baseline investigation.

Intervention

  • Subjects randomized to intervention group or control group
  • Intervention group received supervised endurance and circuit training in groups three times a week for three months, five 20-minute group sessions of diet counseling with a dietitian and follow-up meetings with a physiotherapist monthly thereafter
  • Control group received usual care and treatment and were invited to one single meeting where they were informed about the relationship between lifestyle and health, and a physician, physiotherapist and dietitian took part in the meeting.

Statistical Analysis

  • With the inclusion of 120 subjects, the study had 90% chance of finding a clinically relevant difference in weight development of 3kg
  • Parametric statistical methods were used for quantitative, continuous variables
  • A two-tailed paired T-test was used for analysis of within-groups changes at 12 months, compared with baseline
  • Unpaired T-tests were used for analysis between groups
  • Mean changes and their 95% confidence intervals were calculated
  • For ordinal data such as questionnaires, non-parametric methods were used: A Wilcoxon signed-ranks test was used to detect within-groups changes from baseline to 12 months and a Mann-Whitney U test was used for analysis between groups.
Data Collection Summary:

Timing of Measurements

Subjects visited the health centre on three occasions, at baseline and at three and 12 months, for examinations and blood sampling. 

Dependent Variables

  • Weight in light indoor clothing without shoes
  • Height measured without shoes
  • BMI was taken
  • Hip and waist circumference and waist:hip ratio
  • Maximal oxygen uptake estimated as described by Astrand
  • Health-related quality of life assessed through EuroQol instrument
  • Self-reported physical activity assessed through questionnaire
  • Blood pressure performed by standard auscultatory method
  • Blood samples analyzed for serum lipids, fasting blood glucose, HbA1c, and urine microalbumin

Independent Variables

Intervention or control group.

 

Description of Actual Data Sample:
  • Initial N: 151 middle aged men and women; 75 in the intervention group (48% male, 52% female), 76 in the control group (38.2% male, 61.8% female)
  • Attrition (final N): 123 completed the one-year follow-up (81% completion); 60 in the intervention group, 63 in the control group. Of the seven assigned to the intervention group, one moved from the area, one had a MI, one had another disease, two had pain and two did not show up. Of the six assigned to the control group, one moved from the area, two dropped out and three did not show up.
  • Age: 55.3±6.9 years in the intervention group, 53.0±8.2 years in the control group.

Anthropometrics

Significant baseline differences between groups:

  • Intervention group had more subjects taking lipid-lowering drugs (29.3% vs, 11.8%, P<0.01)
  • Intervention group had a higher waist:hip ratio (0.96±0.09 vs. 0.93±0.09, P<0.05)
  • Control group rated total quality of life higher (P=0.023). 

Location

Primary healthcare centre in Northern Sweden.

 

Summary of Results:

 

Variables

Intervention Group (N=60) Control Group (N=63)

Difference Between Groups (95% CI)

Weight (kg)

-1.5±2.8, P<0.001 -0.7±2.9

-0.8 (-1.86 to 0.20)

BMI -0.5±1.0, P<0.001 -0.2±1.1 -0.3 (-0.62 to 0.20)
Waist circumference (cm) -2.0±2.8, P<0.001 -0.2±2.5 -1.9 (-2.80 to -0.90), P<0.001
Hip circumference (cm) -1.1±1.6, P<0.001 -0.5±2.2 -0.7 (-1.35 to  0.05)
Waist:hip ratio -0.01±0.02, P<0.01  -0.00±0.00 -0.01 (-0.02 to -0.004), P<0.01
SBP (mm Hg) -4.7±10.5, P<0.001 -1.6±11.7 -3.1 (-7.09 to -0.83)
DBP (mm Hg) -3.8±5.0, P<0.001 -1.5±4.9 -2.3 (-4.04 to -0.51), P<0.05
Maximal VO2 (L per minute) 0.14±0.30, P<0.01 0.03±0.31 0.11 (-0.03 to 0.24)
Maximal VO2 (ml per kg) 1.6±3.3, P<0.01 0.7±4.0 0.9 (-0.60 to 2.49)
Total cholesterol (mmol per L) 0.14±0.67 0.16±0.67 -0.02 (-0.33 to 0.30)
HDL cholesterol (mmol per L) -0.03 0.19 -0.01±0.17  -0.03 (-0.09 to 0.42)
LDL cholesterol (mmol per L) 0.3  0.83, P<0.01 0.19±0.50 0.16 (-0.09 to 0.42)
Triglycerides (mmol per L) -0.2  1.00, P<0.05 -0.05±0.77 -0.23 (-0.55 to 0.09)
Fasting blood glucose (mmol/ per L) 0.0±0.49 0.17±0.40, P<0.05 -0.09 (-0.26 to 0.09)

HbA1c (%)

-0.54±0.74, P<0.01

-0.57±1.03

0.03 (-0.67 to 0.71) 

Urine microalbumin (mg per L) 5.62±19.31 10.00±15.27, P<0.05 -4.38 (17.88 to 9.13)
EQ VAS (0 to 100) 8.1±15.7, P<0.001 2.3±17.9  5.3 (-1.10 to 11.65)

Other Findings

After one year, the intervention group significantly increased maximal oxygen uptake, physical activity and quality of life and significantly decreased body weight, waist and hip circumference, BMI, waist:hip ratio, systolic and diastolic blood pressure, triglycerides and glycosylated hemoglobin.

There were significant differences between groups, mean changes (95% confidence intervals) in waist circumference of -1.9cm (-2.80 to -0.90, P<0.001), in waist:hip ratio of -0.01 (-0.02 to -0.004, P<0.01) and in diastolic blood pressure of -2.3mm Hg (-4.04 to -0.51, P < 0.05).  

Author Conclusion:

We conclude that lifestyle intervention in primary healthcare consisting of aerobic exercise and circuit resistance training, in combination with diet counseling and regular follow-up, has favorable effects on several cardiovascular risk factors in patients with a moderate to high risk of cardiovascular disease. The level of physical activity increases and health-related quality of life improves. Such intervention can be implemented in the primary healthcare system.

Funding Source:
Other: Not described
Reviewer Comments:

Significant differences between groups at baseline. Subjects were also taking medications for dyslipidemia, hypertension and diabetes. Authors note the following limitations:

  • No quantitative method for measuring physical activity and the level was assessed only by self-reported questionnaires
  • Control group received information on associations between health and lifestyle on one occasion
  • Study subjects were recruited by letter and may reflect subjects with a greater interest in lifestyle changes, thus the study groups may not be truly representative of the population at risk.
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? No
  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? 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? ???
  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? ???
  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? 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? No
  10.2. Was the study free from apparent conflict of interest? Yes