PWM: Physical Activity and Inactivity of Youth (2006)
Obarzanek E, Schreiber GB, et al. Energy intake and physical activity in relation to indexes of body fat: National heart, lung, and blood institute growth and health study. American Journal of Clinical Nutrition 1994; 60: 15-22.PubMed ID: 8017331
To examine the relationship between obesity, energy intake & physical activity in a large cohort of black & white girls.
- Black or white girls, within 2 weeks of age 9 or 10 years at the time of the first clinic visit,
- Parents of guardians who identified themselves as being of the same race as she was and
- Her parents or guardians completed a household demographic information form and gave informed consent.
Berkeley & Cincinnati sites recruited participants from public & parochial schools that were racially & socioeconmically diverse. Westat recruited participants primarily from the Group Health Association membership listing of families who had girls ages 9-10 years.
Dependent: BMI (height & weight measured following standardized protocol) & Sum of 3 skinfold-thickness measurements.
- Total energy intake, total fat intake & % of energy from total fat & saturated fatty acids (consecutive 3-day food records), Physical activity (3-day physical activity diaries & Physical activity patterns questionnaires), Sedentary activity (assessment of # of hours of television & video watched);
- Income (questionnaire) & Level of education (questionnaire).
Control Variables: Race/ethnicity, Age, Income & Level of education.
Statistical Analysis: Multivariate regression analyses analysis.
Original Sample: 2379 black & white girls (1166 white, 1213 black).
Final Sample: 2147 girls (1044 black, 1103 white)
Location: 3 field centers (Berkeley, CA, Cincinnati, OH & Rockville, MD).
Race/Ethnicity: Black & white girls.
Age: 9-10 y.
- BMI & skinfold thickness were highly correlated in this study (r=0.89).
- Compared with white girls, black girls had higher intakes of energy, grams of total fat, & % of energy from total fat. However, black girls had slightly lower intakes of % of energy from saturated fatty acids.
- Multivariate-regression analyses showed that age, number of hours of television & video watched, percent of energy from saturated fatty acids & the activity patterns score best explained the variation in BMI & sum of 3 skinfold-thickness measurements for black girls (R2 for this model – BMI as outcome - was 0.04 (P<0.0001).
- The best model for white girls included age, # of hours of television & video watched & percent of energy from total fat (R2 for this model – BMI as outcome - was 0.05 (P<0.0001).
- (BMI) For both races, total energy intake, total grams of fat intake & the activity diary scores were not found to be significantly & independently related to BMI.
- (Skinfold thickness) For each race the regression models describing the variation in skinfold thickness were similar to those of BMI.
- For both races, total energy, total grams of fat intake & the physical activity diary scores were not found to be independently related to skinfold thickness.
Total energy intake was not independently & significantly associated with BMI & skinfold thickness in either black or white girls.
- Significant interaction term between race & dietary fat in the regression analysis for skinfold led to different regression models for black & white girls.
- It is possible that racial differences in eating patterns result in different sources of fat being prominent in the diet or better identified & quantified by the food record.
|University/Hospital:||University of California, Berkeley, Children’s Hospital Medical Center, Group Health Association, Maryland Medical Research Institute,|
- Large sample size,
- Study sample included both black & white girls.
- The median levels of physical activity measured in two ways were not fully consistent with each other.
- High intra-individual variation encountered in dietary estimate.
Quality Criteria Checklist: Primary Research
|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)||N/A|
|2.||Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?||N/A|
|3.||Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?||N/A|
|4.||Is the intervention or procedure feasible? (NA for some epidemiological studies)||N/A|
|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?||N/A|
|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?||N/A|
|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)||N/A|
|3.2.||Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?||N/A|
|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?||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?||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%.)||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?||N/A|
|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.)||N/A|
|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?||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?||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?||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?||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?||N/A|
|8.3.||Were statistics reported with levels of significance and/or confidence intervals?||N/A|
|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)?||N/A|
|8.6.||Was clinical significance as well as statistical significance reported?||N/A|
|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|