PWM: Family Influences (2006)
Agras WS, Hammer LD, McNicholas F, Kraemer HC. Risk factors for childhood overweight: a prospective study from birth to 9.5 years. J Pediatr. 2004 Jul;145(1):20-5.PubMed ID: 15238901
To prospectively assess many of the established and hypothesized risk factors for the development of childhood overweight.
- (Eligibility described in journal article: Hammer LD, Bryson S, Agras WS. Development of feeding practices during the first 5 years of life. Arch Pediatr Adolesc Med 199;153;189-94)
- Infants were eligible for participation if they were born at term (>37 weeks' gestational age) and had Apgar scores of at least 7 at 1 and 5 minutes after birth.
- At risk for overweight: above the 85th percentile of BMI.
- Overweight: above the 95th percentile of BMI.
Any congenital abnormalities or experienced any illness during newborn hospitalization.
Newborn infants and their parents recruited from well newborn nurseries at a university hospital, community hospital, and a health maintenance organization in the San Francisco Bay Area.
The following data were collected:
- parental height and weight,
- infant weight and length,
- infancy feeding behaviors (sucking pressure and burst duration),
- early infant weight gain,
- maternal expectations of infant feeding (maternal pushiness) and body habitus (images of male & female infants from thin to plump),
- parent/infant feeding practices,
- parent eating behaviors (dietary restraint, hunger, and disinhibition),
- maternal return to work,
- childhood eating behaviors (picky eating, rapid eating, tantrums over food, non-nutritive food uses),
- 24 hour child caloric intake,
- child activity level and duration of TV viewing,
- child temperament,
- sleep time,
- maternal weight gain (over a five year period, from infant’s age of 0.5 to 5.5 years),
- parent’s concern about child’s weight (underweight and overweight), parent feeding behaviors (non-nutritive food uses and use of food limits),
- laboratory measures of parental behaviors,
- parenting behaviors (authoritarian, authoritative, permissive styles).
Parent behaviors in feeding their children included non-nutritive food uses and the use of food limits, by using an annual questionnaire at ages 2 through 5 years. The scales for parental concerns and nonnutritive food uses were stable over that period, and the results were averaged; however, the measure of food limits varied across time and hence each year was entered separately.
Statistical AnalysisLogistic regression (association between each possible risk factor and the binary outcome above or below the 85th percentile of BMI at 9.5 years), stepwise regression (to understand the mechanism through which low parental concern about their child’s weight may affect overweight), recursive partitioning analysis (to identify subgroups with a differential risk of having a BMI =85th percentile at 9.5 years of age)
Timing of Measurements
Infant weight assessed at 2 weeks of age and six months, infant sucking behavior at 2 and 4 weeks, parent/infant feeding practices collected for the first 3 days of each month until the child was weaned from both breast and bottle, childhood eating behaviors at ages 2, 3, 4, and 5, child temperment at age 5, maternal weight and height at the 5.5 year visit, caloric intake, child activity and laboratory measures of parental behaviors at ages 3 and 5, and sleep time, parent feeding behaviors and parent concerns about child's weight at ages 2, 3, 4, and 5. Parental Attitudes: The parental authority questionnaire was used to measure parenting style, including authoritarian, authoritative, and permissive styles of behavior (Buri’s questionnaire). Parent concerns about child’s weight (overweight & underweight) were assessed by annual questionnaire at ages 2 through 5 years – this is the extent of the explanation of the questionnaire. Data were not separated by gender of child.
Body mass index
Child’s temperament, activity level, hours of sleep, parental concerns about thinness, parental overweight, early feeding measures, early growth, maternal attitudes
Initial N: 216
Attrition (final N): 150 (74 boys, 76 girls)
Age: Birth to 5 years
Ethnicity: Assessed but not stated
Anthropometrics: Of the 150 children, 38 (25.3%) were above the 85th percentile of BMI at 9.5 years of age, including 14 (9.0%) above the 95th percentile.
Location: San Francisco Bay Area
Predicting Child Overweight
Strongest relation was with parental BMI (W=13.7, p<0.001), which was mediated by temperament of the child assessed as a combination of approach and impulsivity (W=6.6, p<0.01). This factor is correlated with an active personality and anger/frustration, indicating highly emotional behavior.
The remaining risk factors were:
- low parental concern about their child’s thinness (in other words, the parents are not worried that their child was too thin) (W=5.2, p<0.02);
- children with persistent tantrums over food (W=9.3, p<0.002);
- children’s hours of sleep at ages 3 to 4 years (W=6.6, p<0.01).
Explaining Parental Concern
We noted above that the authors identified one aspect of parental concern that was associated with (though, not in a causal manner) childhood overweight: low concern over thinness. A clearer statement of this variable would be: parents not worried about their child being underweight.
The authors examined the factors associated with different kinds (and levels) of parental concern about their child's weight. Four possibilities for parental concern were examined:
- High concern over child underweight (that is, worried that the child was too thin)
- Low concern over child underweight (that is, not worried about underweight)
- Low concern over child overweight (that is, not worried about overweight)
- High concern over child overweight (that is, worried that the child was too fat)
Of the four possible types and levels of concern, only #2 (low concern about child being underweight) was found to be associated with child overweight. So, the authors examined what factors seemed to be associated with this type of parental concern.
The predictors of low concern about child being underweight were:
- weight gain in the first 6 months of life (B= -0.3, t(118)= -3.6, p=0.001) (strongest predictor),
- followed by birth weight (B= 0.24, t(118)= -2.8, p=0.006),
- maternal preference for a thin baby (B= 0.19, t(118)= 2.8, p=0.006).
Low concerns about thinness seemed to reflect a parent with a preference for a thin child faced with a developmental pattern of higher birth weight, rapid weight gain in the first 6 months of life, and as show by the correlates of this risk factor, an eating pattern comprising rapid eating and a high interest in food.
In other words, if the parent wants a thin child, but has a big baby who gains weight quickly, chances are the parent is not going to be worried that their child is underweight.
Other Factors Associated with Child Overweight
Tantrums over food were positively related to overweight, with persistent tantrums about 3 times more likely to occur in those who would become overweight. Although 82% of children had such tantrums at some time during childhood, only 19% had persistent tantrums reported annually from 2 through 5 years of age.
Hours of sleep reported annually from 3 through 5 years were negatively related with overweight; children who were to become overweight were reported to sleep about 30 minutes less on average than those who would remain normal weight. This difference was almost entirely due to shorter daytime sleep, with only 5 minutes’ difference in night-time sleep.
A child with an overweight/obese parent had a 48.1% chance of becoming overweight obese, whereas a child with normal weight parents had a 13.3% chance of becoming overweight or obese.
For parents who were not overweight, if their child had persistent temper tantrums over food during years 2 through 5, 31.2% would become overweight compared with 9.8% for those without tantrums.
For children with overweight parents who were not worried that their child was underweight, reflecting the developmental pattern described above, 62.9% would become overweight/obese compared with 33.6% for those without this temperamental profile.
Parental attitudes toward their child’s weight may lead to behaviors that increase the risk of their child becoming overweight.
Child’s behaviors such as temper tantrums and the behavior difficulties posed by the highly emotional child, which in turn may lead to overfeeding, are amenable to parental counseling. The findings of this study suggest that at-risk children and their parents may be identifiable in the first few years of a child’s life, affording the opportunity for early preventive interventions.
- Prospective design of 10 years
- Authors' method of gathering information on parental attitudes does not indicate that parental attitudes (such as being worried about underweight) are prior to child weight changes. Thus, the statement that parental attitudes "may lead" to childhood overweight are out of place. Indeed, in explaining parental attitudes it is child weight gain patterns that influence parental attitudes and not the other way around.
- Small sample size.
- Level of parental education is higher than that of the general population.
- Percentage of minorities is lower than that of the general population.
- Some of the critical assessments (i.e. childhood personality attributes) were obtained by parental report, possibly biasing the results of this assessment.
- A substantial number of the original participants dropped out by 9.5 years of age or provided incomplete data. Those who dropped out tended to be less well educated than those who did not, again potentially biasing the results.
Other commentsControl variables not clearly stated, if assessed.
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?||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|
|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)||N/A|
|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?||???|
|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.)||???|
|5.3.||In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?||???|
|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?||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)?||???|
|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|