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National Coverage Determination (NCD)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

Compare the serum lipid level responses to the American Heart Association (AHA) Step 1 Diet between women and men with hypercholesterolemia.

Inclusion Criteria:

Subjects obtained through a community cholesterol screening with:

  • Total cholesterol 5.17 to 8.99mmol per L
  • Triglycerides less than 5.08mmol per L
  • 80% to 130% IBW.
Exclusion Criteria:
  • History of MI
  • CABG surgery in past three months
  • History of unstable angina
  • uncompensated CHF, liver disease, pancreatitis, thyroid disease, cancer or serious GI disease
  • Medications: corticosteroids, oral contraceptives, replacement hormones, fiber supplements, lipid lowering medications, fish oils, tetracycline
  • Pregnant
  • History of alcohol or drug abuse.
Description of Study Protocol:

Recruitment: Recruited subjects 30 to 70 years via community cholesterol screening

Design:  cohort study (subjects divided into tertiles based on initial serum cholesterol level)

Intervention: Instruction on AHA Step I diet by individual and group classes given by RD every two weeks.

Statistical Analysis:

  • within individual changes by t-test
  • between-group comparisons by ANOVA and Tukey test for differences found between groups
Data Collection Summary:

Timing of Measurements: Baseline and final Medical history, lipids, height, weight, three-day diet records after four and eight weeks

Independent Variable:

  • AHA Step 1 diet and bi-weekly individual or group instruction for 8 weeks by a Registered Dietitian

Dependent Variables:

  • Serum lipids
  • Nutrient intake
  • Body weight
Description of Actual Data Sample:

Initial N: 164 (61% male) aged 30 to 70 were counseled for AHA Step I diet

Attrition (final N): 63 women and 99 men (total of 162) completed the study

Anthropometrics Baseline: 80 to 30% of IBW; serum cholesterol between 5.17mmol/L and and 8.99 mmol/L and triglycerides < 5.08 mmol/L

Location: Lexington, KY

Summary of Results:

Overall:

Serum total cholesterol significantly reduced 9.2% for women and 7.2% for men (P<0.05).

LDL-cholesterol significantly reduced 9.2% for women and 9.8% for men (P<0.05).

Triglycerides significantly reduced for women (11.3%; P<0.05) but not for men.

Changes in Blood Lipids (Women)
Outcome

Mild Cohort

initial to final

(% change)

Moderate Cohort

initial to final

(% change)

Severe Cohort

initial to final

(% change)

All Women

initial to final

(% change)
Total Cholesterol (% change)

5.79±0.08 to 5.66±0.10

(-2.2%)

 6.54±0.09 to 5.95±0.13

(-9.0%)a,b

6.54±0.09 to 6.59±0.14

(-12.1)%a,b

6.74±0.09to 6.12±0.09

(-9.2%)b
 LDL-Cholesterol (% change)

3.72±0.10 to 3.62±0.13

(-2.7%)

 4.40±0.06 to 3.96±0.13

(-10%)a,b

5.19±0.08 to 4.51±0.12

 (-13.1)%a,b

4.45±0.08 to 4.04±0.10

(-9.2%)b
 HDL-Cholesterol (% change)

1.47±0.10 to 1.47±0.10

(0%)

1.32±0.08 to 1.24±0.08 

(-6.1%)a

1.37±0.05 to 1.27±0.05 

( -7.3%)a,b

1.37±0.05 to 1.32±0.05 

(-3.6%)b
 Triglycerides (% change)

1.30±0.14 to 1.21±0.17 

(-6.9%)

1.76±0.20 to 1.63±0.14

(-7.4%)a

2.08±0.25 to 1.73±0.15

 (-16.8%)a,b

1.77±0.14 to 1.57±0.09 

(-11.3%)b

a Different from Mild hyperlipidemia cohort (P<0.05)    b Different from initial to final for cohort (P<0.05)

Changes in Blood Lipids (Men)
Outcome

Mild Cohort

initial to final

(% change)

Moderate Cohort

initial to final

(% change)

Severe Cohort

initial to final

(% change)

All Men

initial to final

(% change)
Total Cholesterol (% change)

5.77±0.05 to 5.53±0.08

(-4.2%)b

6.49±0.03 to 5.95±0.10

(-8.3%)a,b

7.40±0.10 to 6.59±0.16

(-10.9%)a,b

6.41±0.08 to 5.95±0.08

(-7.2%)b
 LDL-Cholesterol (% change)

3.98±0.05 to 3.83±0.08

 (-3.8%)b

4.50±0.08 to 4.01±0.10

 (-10.9%)a,b

 5.30±0.13 to 4.53±0.16

(-14.5%)a,b

4.50±0.08 to 4.06±0.08

(-9.8%)a,b
HDL-Cholesterol (% change)

1.01±0.03 to 1.01±0.03

(0%)

  1.06±0.05 to 1.03±0.03

(-2.8%)

1.19±0.05 to 1.11±0.05

 (-6.7%)b

 

1.06±0.03 to 1.03±0.03

 (-2.8%)b

 
Triglycerides (% change)

1.67±0.12 to 1.52±0.09

(-9.0%)

 2.01±0.17 to 1.92±0.15

(-4.5%)

1.94±0.14 to 2.15±0.23

 (+10.8%)

 

1.86±0.09 to 1.82±0.09

 (+10.8%)

 

a Different from Mild hyperlipidemia cohort (P<0.05)    b Different from initial to final for cohort (P<0.05)

Other Findings:

  • Responses of men and women paralleled each other, with greater responses in groups with higher intitial levels.

 

Author Conclusion:
  • Women and men respond similarly to an AHA Step 1 diet
  • Persons with highest initial serum cholesterol levels had the greatest dietary response
  • Aggressive dietary intervention is effective in the treatment of hypercholesterolemia in both men and women.
Funding Source:
Industry:
Proctor & Gamble Co.
Other:
Reviewer Comments:
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.) 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? Yes
  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? 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.) No
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? Yes
  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? 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? 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)? No
  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