Pediatric Weight Management

PWM: Physical Activity and Inactivity of Youth (2006)

Citation:
Locard E, Mamelle N, Billette A, Miginiac M, Munoz F, Rey S. Risk factors of obesity in a fiver year old population.  Parental versus environmental factors.  Int J Obes 1992;16:721-9. PubMed ID: 1330951
 
Study Design:
Case-control
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To find correlations between certain environmental factors and obesity in childhood, and to measure the influence of the environmental factors after taking the parental history of obesity into account.

Inclusion Criteria:
not specified
Exclusion Criteria:

‘important data missing’

Description of Study Protocol:

Recruitment

From a population of 9261 children undergoing a medical check-up before entering first grade classes in 202 elementary schools in 1988-89. Not well described, but appear to have been randomly selected.  No formal refusal.  If child selected as a case and no parent, parent invited later.  If selected as control and no parent, or if parents did not answer a second invitation, was replaced by another non-OB child from same class, the next one to be pre-selected on a randomized list. 

Design

Children measured by school doctors and nurses, perinatal data collected from personal health record (data source not described), and child’s mother or father interviewed by doctors for about 20 min.

Statistical Analysis

  • Power calculation provided (estimated 250 cases, 500 controls)
  • Chi2 or Student’s t tests for testing relationship between obesity and other factors
  • Mantel-Haenszel tests to take confounders into account and calculate adjusted ORs
  • Logistic regression model to estimate risk of obesity
Data Collection Summary:

(no blinding)

Independent variables

  • Snacks between meals, Snacks in front of TV (questionnaire)

Dependent variables

  • Obesity based on weight for height Z score (measured; using French weight charts) >2

Other variables

  • Parental data (age, height, weight presently and at age 20, ethnic origin, SES)
  • Family structure (single parent, separated, only child, child born at least 5 years after nearest sibling)
  • Perinatal data (gestational age, birth weight, birth rank, mother’s age, breast feeding)
  • Child’s lifestyle (lunching place from birth to date, after school care, duration of sleep, frequency of TV viewing)

Control variables

  • Parental overweight (parental overweight if one or both had BMI above limits of Rolland-Cachera (1991) at present or at age 20)
  • Birth overweight (overweight at birth if large for gestational age, sex, birth rank, mother’s height and pre-PG weight, using method of Mamelle, 1992)
Description of Actual Data Sample:

Final sample – 1,031 (327 cases, 704 controls; 50% of cases and 52% of controls were boys)

Original sample – 412 of 441 OB, 838 of 8820 non-obese

Age – 5.4 y

Ethnicity – not specified, except that told 8.0% of cases and 4.4% of controls had mother of Southern European origin

Other demographics – SES levels provided for cases and controls (Table 2), but levels [1-IV] not defined; 6.5% of cases and 7.5% of controls from single parent households; % of cases vs. 24.6% of controls had mothers with < secondary school education and 20.4% of cases and 20.2% of controls had mothers with no formal education (none of these demographic variables differed significantly between cases and controls)

Location – 2 French districts (Isere & Rhone)

Summary of Results:

Unadjusted analysis

  • Snacks between meals related to obesity (48.2% cases vs. 41.6 % controls; estimated odds ratio 1.3, 95% CI 1.0-1.7)
  • Snacks during TV viewing not related to obesity (20.1% cases, 21.4% controls, p<.05; estimated odds ratio 0.9, 95% CI 0.7-1.3)
  • Other factors associated with obesity:  Parental overweight, Birth overweight, Southern European origin of mother, Frequency of TV viewing >=4 hr/d, Sleep duration  10-11 or <10 hr/night (see Tables 1-3 for ORs)

Controlling for parental overweight and birth overweight

  • Children with parental overweight take more frequent snacks than in non-overweight families (55% vs 49%, p <.001)
  • But risk of obesity related to snacks is not higher in overweight families (odds ratio = 1.1, ns) than non-overweight families (odds ratio = 1.2, ns)
  • After adjusting for parental overweight, relationship between snacking and obesity disappeared (odds ratio = 1.1, ns)
  • Other factors associated with obesity after adjusting for parental overweight:  high TV viewing, short sleep duration
  • Birth overweight did not appear confounding for snacking (or any other variables examined)

Multifactorial modeling

  • Snacking not included in modeling
  • After controlling for parental overweight, short duration of sleep related to obesity (odds ratio = 1.4, 95% CI 1.0-1.9, p = 0.04), but TV viewing no longer related
Author Conclusion:

The results show that parental overweight and birth overweight are closely related to the child’s obesity at five years of age. The environmental factors which contribute to child obesity are:  southern European origin of the mother, snacks, excessive TV viewing, and more importantly, short sleep duration.  After taking parental overweight into account, the relationship between obesity and short sleep duration persist independently of TV viewing.

Contrary to findings among North American adolescents (Gerbner, 1982), the snacks consumed while watching TV are not linked with obesity in our population, since snack consumption while watching TV is  no more frequent in obese than in non-obese children.  This suggests that TV viewing would act rather by reducing energy expenditure.

Funding Source:
Government: INSERM
Not-for-profit
0
Foundation associated with industry:
Other: GREPS-Groupe de Recherche en Education Pour La Sante,
Reviewer Comments:

Strengths:

  • Examines multiple potential related factors;
  • fairly large sample size;
  • subjects appear to be randomly selected;
  • no difference between cases and controls on most demographic variables tested.

Weaknesses:

  • Definition of snacking not provided,
  • use of French obesity standard precludes comparison of prevalence to other studies,
  • demographics unclear for some variables,
  • no comparison of those included vs. excluded from study.
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) N/A
  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) N/A
 
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? No
  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.) 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? 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%.) No
  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? 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.) No
  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? Yes
  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? Yes
  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? No
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  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? No
  8.7. If negative findings, was a power calculation reported to address type 2 error? Yes
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