NGHC: Prevention of Chronic Disease (2013)

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

This study tested the hypothesis that a year long, school-based education program can result in lifestyle changes that decrease risks for heart disease such as hypercholesteroiemia, obesity, sedentary lifestyles, hypertension, and exposure to tobacco smoke. The following questions were addressed:

  1. To what extent did knowledge scores about healthy lifestyles and prevention of CHD change from beginning to the end of each program, and between experimental and control groups.
  2. What portion of children in each group demonstrated risk factors for CHD? Were there changes?
  3. What information about healthy lifestyles and prevention of CHD did children share with their families to improve parental lifestyle?
Inclusion Criteria:
Students enrolled in the 3rd grade in the fall of 1999 who were able to read and write in English at the appropriate grade level, had parental consent, at least one parent who was involved in the study and assented to participate.
Exclusion Criteria:
See inclusion criteria above.
Description of Study Protocol:

American Heart Association’s school-based program HeartPower! focuses strictly on risk factors for heart disease and includes a family component. The HeartPower! kit for grades 3-5 includes a teacher resource book, posters, instructional activities on how the heart works, audiocassette tapes, videocassette tapes, stethoscopes and alcohol swabs. For 30 minutes per week, throughout the 1999-2000 school year, pediatric nursing students from the Ohio State University taught the AHA HeartPower! Program in one school and taught other health-related topics in the comparison school.

Data Collection Summary:


  • Knowledge of healthy lifestyles and CHD (student survey & 10-question knowledge test),
  • Cholesterol level (measured with a Chemcard),
  • Nutritional assessment – number of servings of foods high in sugar and/or fat (24-hour food recall),
  • Obesity measured by height & weight & Body fat % - > 20% = > normal range for boys & > 24% = > normal range for girls (Bio-electric-impedance analysis),
  • Sedentary lifestyle (survey containing questions about exercise habits),
  • Hypertension - > 95th % for age on 3 separate occasions(measured BP),
  • Exposure to cigarette smoke (scale for assessing the intensity of exposure to ETS) & Parental involvement (parents were asked to complete two activities related to the structure of the heart & nutrition – prior to implementing the intervention, all parents were asked to complete a 29-item survey with questions related to family history, risk factors for CHD and lifestyle choices).


School-based intervention HeartPower! Program.

Control Variables

Results were reported by gender. Otherwise no control variables were noted.

Statistical Analysis

Independent t-tests were used to test the differences between groups, and dependent t-tests were used to test differences over time within groups. ANOVA was used to examine the interaction between time and group.

Description of Actual Data Sample:

Original Sample: A convenience sample of 58 3rd grade children participated in the study (33 in the experimental group & 25 in the comparison group).

Withdrawals/Drop-Outs: One student from each group withdrew from the study.

Final Sample: 32 children in the experimental group (19 males & 13 females) and 24 children in the control group (9 males & 15 females)

Location: a large metropolitan area in a Midwestern city (likely to have been in Ohio).

Race/Ethnicity: Experimental sample: 51.5% Caucasian, 39.4% African-American, 3% Hispanic & 6.1% other. Control group: 28% Caucasian, 40% African-American, 4% Hispanic & 23% other.

SES: not stated.

Summary of Results:

Knowledge of healthy lifestyles

Students who participated in the HeartPower! Program showed improvement (p<0.025) in their knowledge of the cardiovascular system and health risk factors that may lead to heart disease.


Cholesterol levels were relatively consistent throughout the study.

Body fat percentage

Males: In the experimental group, one male converted from abnormal levels to normal levels, whereas none of the males in the control group changed to normal levels.

22% of the control group males moved into the high-risk category by the end of the study.

Females: During the course of the program, 7% of the females in each group moved into the elevated body fat % category. However. 13% of the females in the control group moved from the high-level to the normal level category by the end of the program.

Experimental group body-fat percentages held steady over the school year, while children in the control group developed higher body fat percentages. (Whether or not these were statistically different between groups was not reported.)


Students who participated in the HeartPower! Program showed modest improvements in hypertension.

  • 8-year-old males: 14% in the experimental group has a Diastolc Blood Pressure greater > 95th % for age but decreased to normal by the end of the study. In the control group, 14% maintained elevated Diastolc Blood Pressure .
  • 8-year-old females: Of the 50% in the experimental group with elevated Diastolc Blood Pressure , only 10% had elevated levels in the spring. Diastolc Blood Pressure were elevated in 23% of 8-year-old females in the control group in autumn, decreased to 8% in winter, then elevated to 15% by spring.
  • 9-year-old males & females: All in the experimental group maintained normal Diastolc Blood Pressure throughout the study.   All 9 y.o. males maintained normal levels. Half of the 9-year-old females had elevated Diastolc Blood Pressure , but they decreased to normal levels.  

Exposure to Tobacco

Students who participated in the HeartPower! Program showed modest improvements in exposure to tobacco smoke. No homes in the control group eliminated levels of ETS by the end of the study. 6% of the children in the experimental group reported a decrease in the amount of smoking in the household throughout the year.

Consumption of sweets and fat

By the end of the study, 12% of the experimental group & 20% of the control group reported eating at least 2 servings of sweets and fat per day. In the experimental group, 21% of the children had decreased their consumption of fats by the end of the study. Similar results for decreasing consumption of fat were found in the control group; however, more children maintained or developed abnormal dietary habits during the study.

Self-report Exercise

No significant results.

Author Conclusion:

CHD disease has a multidimensional etiology and a year-long program, 30-minutes per week will not be sufficient to reach all of the goals for prevention of CHD.

Funding Source:
University/Hospital: Ohio State University
Foundation associated with industry:
Reviewer Comments:
  • Generalizability was limited in this study as a convenience sample was used.
  • Calories and the amount of saturated fat were not calculated due to the children’s inability to verbalize portion sizes.
  • Exercise was assessed using self-reports, which is not likely to capture the true amount of aerobic engaged in by children.
  • Parents’ interest in the study declined over time.
  • It was unknown if the study groups were comparable. Authors did not test – based on race/ethnicity study groups did not appear to be comparable.
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.) Yes
  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? No
  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%.) No
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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? No
  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)? 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? 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