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NC: Cardiovascular Disease Risk Factors (2007-2008)

Citation:

Kuller LH, Simkin-Silverman LR, Wing RR, Meilahn EN, Ives DG. Women's Healthy Lifestyle Project: A randomized clinical trial: results at 54 months. Circulation 2001 Jan 2; 103 (1): 32-37.

PubMed ID: 11136682
 
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 test the hypothesis that reducing saturated fat and cholesterol consumption and preventing weight gain by decreased caloric and fat intake and increased physical activity would prevent the rise in LDL cholesterol and weight gain in women during peri-menopause to post-menopause.

Inclusion Criteria:
  • Women
  • Age 44 to 50 years.
Exclusion Criteria:
  • Prior hysterectomy
  • Hormone replacement therapy.
Description of Study Protocol:

Recruitment

  • Sample derived from voter registration lists in Allegheny County, Pennsylvania between 1992 and 1994
  • Phone interview and baseline screening to determine eligibility. 

Design

Randomized to assessment only or lifestyle intervention group.

Blinding Used

None. 

Intervention

Five-year cognitive-behavioral program aimed at preventing the increase in LDL cholesterol levels, preventing weight gain and increasing leisure-time physical activity. Goals included:

  • Modest weight loss goal of five to 15 pounds (reduce kcal intake to 1,300kcal until weight goal achieved)
  • Decrease fat intake to 25% of kcal
  • Lower saturated fat intake to 7% of kcal
  • Lower dietary cholesterol intake to 100mg daily
  • Increase physical activity to 1,000 to 1,500kcal expended weekly

Intensive group program during the first six months and follow-up individual or group sessions from six through 54 months.

Statistical Analysis

  • Descriptive statistics to describe baseline and socio-demographic variables
  • T-tests and ANOVA to test differences between intervention and control groups on risk factors.
Data Collection Summary:
  • Timing of measurements:
    • Baseline, six, 18, 30, 42 and 54 months
    • Main endpoint difference in the change in LDL cholesterol and weight between intervention and assessment-only groups at the end of the 54 months
  • Dependent variables: None
  • Independent variables: Five-year cognitive-behavioral program aimed at preventing the increase in LDL cholesterol levels, preventing weight gain and increasing leisure-time physical activity
  • Control variables: None.

 

Description of Actual Data Sample:
  • Initial N: N=535 (intervention group N=260; assessment group N=275)
  • Attrition (final N): Not available
  • Age: 47±1.6 years
  • Ethnicity: 92% White
  • Other relevant demographics: None
  • Anthropometrics: No significant difference in the groups on blood pressure, lipid levels, BMI, waist to hip ratio, fasting glucose and physical activity
  • Location: Pennsylvania, USA.

Comparison of Baseline Characteristics in Intervention and Assessment Groups
Variable Assessment Group Mean (SD)

Intervention Group Mean (SD)

BMI 25±3 25±3
Physical Activity, kcal per week 1,412±1,386 1,248±1,064
Total Cholesterol 190±24 190±24
LDL Cholesterol (mg/dL) 116±22 115±22

  • In both groups, 56% of participants were pre-menopausal (menstruating regularly), 10% were peri-menopausal (having missed three to 11 consecutive periods) and 35% were post-menopausal (having missed 12 consecutive periods or having had a hysterectomy)
  • 13 in the intervention group and 14 in the assessment group had hysterectomies at 54 months
  • 30% (80 of 263) in the assessment group and 32% (79 of 245) in the intervention group were on hormone replacement therapy.

 

Summary of Results:

 

Variables

Six-Months

Mean

 L**

Six-Months

Mean 

 A

54-Months

Mean

   L

54-Months

Mean

A

* Indicates Statistical Significance

Weight, pounds

-10.7*

-0.049

-0.18*

5.2

P<0.01

Waist Circumference, cm

 -4.2*

-0.36

 -2.9*

 -0.46

P<0.01

LDL Cholesterol, mg/dL

-10.6*

-0.06

  3.5

 8.9

P<0.01

HDL Cholesterol, mg/dL -2.4* -0.10  2.3 3.1

P<0.01

Triglycerides, mg/dL -4.0*  4.9  18.2*  29.9

P<0.01

ApoB, mg/dL -6.5* 0.27  5.9* 10.5

P<0.01

Systolic BP, mmHg -3.5*  -1.2 -1.2  0.20

P<0.01

Diastolic BP, mmHg -2.2*  -0.08  1.5  2.2

P<0.01

** L = Lifestyle intervention group; A = Assessment-only group 

Change from Baseline in Risk Factor Levels By Group

  • At 54 months, 27% of the intervention group compared with only 16% of the assessment-only group had LDL cholesterol levels less than 100mg per dL, whereas 40% of the assessment-only group and only 32% of the intervention group had LDL cholesterol levels greater than 130mg per dL (P=0.007, Mantel-Haenszel test for linear-comparison between the assessment and intervention groups)
  • At the 54-month exam
    • There was a 3.5mg per dL increase in LDL cholesterol in the intervention group and an 8.9mg per dL increase in the assessment-only group (P=0.009)
      • Weight decreased 0.2 pounds in the intervention and increased 5.2 pounds in the assessment-only group (P=0.000)
      • Triglycerides and glucose also increased significantly more in the assessment-only group than in the intervention group
      • Waist circumference decreased 2.9cm in the intervention compared with 0.5cm in the assessment-only group (P=0.000).

Distribution of Change in Reported Dietary Intake Based on Food Frequency Assessment: Intervention (I) Compared with Assessment-Only Group (A)
Variables

Baseline

   A

Baseline

L

54 months

   A

54 months

                 L

Statistical significance

I vs. A at 54 months

Percentage Saturated fat of Total Kcal 11.5 11.8 10.9 9.0 P=0.000
Percentage Total Fat of Total Kcal 32.5 32.6 30.4 25.6 P=0.000
Dietary Cholesterol, mg per day 196 197 212 154 P=0.000

Change in Risk Factors by Menopausal Status at 4.5 Year Follow-Up
Variables

Pre-menopausal (N=282)

 L

Pre-menopausal (N=282)

                A

Pre-menopausal (N=282)

                    P

Post-menopausal (N=177)

 L

Post-menopausal (N=177)

                 A

Post-menopausal (N=177)

P

LDL Cholesterol, mg/dL 3.4 7.4  NS 3.2  11.9 0.031
Total Cholesterol, mg/dL 9.1 15.1 0.022 12.2 22.5 0.015
Triglycerides, mg/dL 13.0  25.0  0.023 24.1 35.9 NS
ApoB, mg/dL 5.0   9.3 0.037 6.1 12.6 NS
Weight, pounds -3.0 0.25 0.000 -2.5 -1.3 NS

Change in systolic blood pressure and diastolic blood pressure were not significant at 54 months. 

Author Conclusion:
  • A five-year cognitive behavioral program that combined dietary changes, a reduction in calories and total fat calories, and a decrease in both saturated fat and total fat calories, along with increasing leisure time physical activity, resulted in a significantly smaller increase in LDL cholesterol levels over 54 months in the intervention compared with the assessment-only group. 
  • There were also significant differences in triglycerides, blood glucose and insulin for the intervention compared with assessment-only group 
  • Differences in weight gain were also maintained over the 54 months of the trial
  • The trial was successful in reducing the rise in LDL cholesterol during peri-menopause to post-menopause but could not completely eliminate the rise in LDL cholesterol 
  • The trial was successful in preventing the increase in weight from pre-menopause to peri-menopause to post-menopause.

 

Funding Source:
Government: NIH
Reviewer Comments:
  • No mention of blinding
  • Very well-matched controls.
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.) N/A
  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? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  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.) ???
  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? N/A
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  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? N/A
  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? N/A
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