PWM: School-based Programs to Prevent Overweight (2006)

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

To reduce NIDDM risk factors among Zuni high-school-age youths.


Inclusion Criteria:
  • Zuni Indian Reservation High-School aged youth
Exclusion Criteria:
  • Not described
Description of Study Protocol:


  • Zuni Indian Reservation High-School aged youth were recruited from two high schools: 1) Zuni High Scool (ZHS) and Twin Buttes High School (TBHS).


  • Non-Randomized Trial
  • Program created after literature review & 6 months of formative assessment in community.
  • Multiple cross-sectional measures of all 11th & 12th graders at baseline, end of 2 y, and end of 4 y (only ht, wt, knowledge/attitudes assessed in all 9th & 10th graders)
  • Intervention for 4 school years (fall 1993- spring 1997), but results presented for midpoint (after 3 y).

Statistical Analysis

  • Student t-tests used to test differences in Zuni vs. Anglo adolescents (Anglos recruited from same age cohort residing in Tucson area; no other information provided)
  • Other statistical tests not described
Data Collection Summary:

Timing of Measurements:

  • Program created after literature review & 6 months of formative assessment in community.
  • Multiple cross-sectional measures of all 11th & 12th graders at baseline, end of 2 y, and end of 4 y (only ht, wt, knowledge/attitudes assessed in all 9th & 10th graders)
  1. School food supply modification: sugar-free beverages in vending machines (transitioned in so that at onset 0 available and by year 3 only sugar-free beverages available); water coolers installed (beginning year 2); healthy snacks sold by wellness center (beginning year 2; no snack vending machines on campus ever); 3-h workshop, provision of recipes & list of alternative vendors provided to foodsvc staff)
  2. School classroom education: integrated into existing curriculum (pilot education units, diabetes ed resource center, 2-d faculty training workshops [years 1 & 2; voluntary but paid attendance], one-on-one work sessions with interested faculty [years 2 & ], team teaching)
  3. School wellness facility: (at larger high school) outfitted with free weight equipment, treadmills, exercise bikes, stair step machines, exercise mats, boxing equipment, mountain bikes, roller blades, pool table & video machines (periodically turned off) to encourage facility use; hiking, biking, roller blading, & swimming trips to public pool let by staff & teen network leaders (frequency not stated)
  4. Supportive social networks: community network (via presentations to Parent-Teacher Organizations and attending meetings of other youth-oriented organizations), faculty network (via presentations at orientation meeting, regularly scheduled faculty meetings and at 1 & 2-d interactive workshops), youth network (6-12 youths who are paid hourly to assist with data collection, plan program-related school events, & monitor wellness center activities)

Dependant Variables:

  • Obesity (BMI and BIA)
  • Body fat distribution (waist & hip circumference)
  • Insulin resistance (partial [30-min] OGTT; received $ for this measure)
  • PA (1-2 activity recalls)
  • Physical fitness (1-2 d heart rate monitoring, step test & recovery heart rate)
  • Consumption of sweetened beverages (24-hr recall)
  • Consumption of high-fiber foods (24-hr recall)
  • Knowledge/attitude/beliefs (questionnaire)

Independant Variables:

  • Zuni Diabetes Prevention Program (see above)

Control Variables:

  • None

Statisical Analysis:

  • Student t-tests used to test differences in Zuni vs. Anglo adolescents (Anglos recruited from same age cohort residing in Tucson area; no other information provided)
  • Other statistical tests not described
Description of Actual Data Sample:

Initial N: Not described

Attrition: 119 adolescents in year 1 (66 female, 53 male), 173 adolescents in year 3 (83 females, 90 male), 9th – 12th grades

Age: 119 adolescents in year 1 (mean age 17.2 y), 173 adolescents in year 3 (mean age 17.9 y), 9th – 12th grades

Ethnicity: 100% Zuni Native American

Anthropometrics: BMI Group Anglo Female and Male: 20-23 with majority above 24

Location: Zuni Indian reservation New Mexico (population 10,000); 2 high schools (enrollment 300-350 in one, 70-90 in the other)

Summary of Results:

Significant Findings:


  • BMI higher at year 1 for Zuni vs. Anglo comparison group, p<0.05 for females, p<0.01 for males)

Beverage Consumption:

  • Decreased sweetened beverage intake (>80% of beverages consumed by >60% of students were sweetened in year 1, <50% of beverages consumed were sweetened in year 3, p<0.05)

Other findings:

  • Selected preliminary midproject results of the Program suggest that using an insidious and pervasive intervention model can result in physiological and behavioral change.
  • Within 2 years of intervention, Zuni high school students had decreased BMI, decreased consumption of sugared beverages, increased consumption of dietary fiber, decreased sitting pulse rates (suggesting improved cardiovascular fitness), and increased glucose/insulin ratios (suggestion a decline in the prevalence of hyperinsulinemia).
  • Although only the changes in beverage consumption and insulin levels are statistically significant, the trends noted from a comparison of year 1 and year 3 assessment measures indicate that behaviors are changing in a direction commensurate with goal designed to reduce the prevalence of NIDDM risk factors in youth.
  • No change in fiber intake (g/d; though trend in expected direction)
  • Increased fitness (decreased sitting pulse rate, p<0.05)Increased fasting plasma glucose (p=0.001 for females; NS for males)
  • No change in 30-min postprandial plasma glucose (though trend in expected direction)
  • Decreased fasting & 30-min postprandial plasma insulin (p=0.005 and 0.05, respectively for males; NS for females)
  • No change in BMI from year 1 to 3 (though trend in expected direction)
Author Conclusion:
  • Midpoint results indicate a significant reduction in soft drink consumption and an increase in glucose/insulin ratio's. suggesting a decline in the incidence of hyperinsulinemia.
Funding Source:
Government: NIH, NIDDK, Zuni Public School District
University/Hospital: University of Arizona
Reviewer Comments:
  • Multi-compnent Trial
  • No control group
  • Comparison of year 1 and year 3 groups not controlled for potential confounders & limited comparison of differences between groups
  • Inclusion/exclusion criteria not well described Participation rate not provided Statistics not well described.
  • Program in 4th year of implementation at time of publication. Additional results in: Ritenbaugh C., Teufel-Shone NI, Aickin MG, Joe JR, Poirier S, Dillingham DC, Johnson D, Henning S, Cole SM, Cockerham D: A lifestlye intervention improves plasma insulin levels among Native American high school youth. Prev Med 2003; 36: 309-19.
  • Difficulty employing qualified staff for short-term program Frequent turnover in school faculty/staff; faculty network composed primarily of 4-5 core faculty
  • Physical distance b/t local program personnel & program directors at university
  • Conflicts b/t school administrators & program directors (e.g., program PE period not implemented because of concern over decreased academic time)
  • Concern over lack of adult supervision with teen workers
  • Difficulty involving PTO
  • Wellness center being opened during day provided some students with place to ‘hide out’ and cut classes
  • Limited weekend use of center
  • Limited integration of diabetes education into curriculum due to frequency faculty turnover & inadequate administrative support
  • Limited modification of school cafeteria foods
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? No
  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? No
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) No
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  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? No
  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.) No
  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? No
  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? No
  4.4. Were reasons for withdrawals similar across groups? No
  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? 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? No
  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? No
  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? ???
  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? 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)? N/A
  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