The epidemiology of overweight and obesity among Australian children and adolescents, 1995-97

A study attempts to determine the population prevalence of overweight and obesity among Australian children and adolescents, based on measured body mass index (BMI) to determine if overweight and obesity are distributed differentially across the population of young Australians. Data from three independent surveys were analyzed and results indicate that the population prevalence and distribution of overweight, obesity and overweight/obesity combined were 79%-81%, 14%-16%, 5% and 19%-21% (boys) respectively, and 76%-79%, 16%-18%, 5%-6% and 21%-24% (girls). There were no consistent relationships between the prevalence of overweight/obesity and sex, age or SES. It is concluded that some 19%-23% of Australian children and adolescents are either overweight or obese. Only cultural background differential warrant a targeted health promotion response.

Parent-reported health status of overweight and obese Australian primary school children: a cross-sectional population survey

Introduction: Childhood overweight/obesity is associated with poor physical and psychosocial health in clinical samples. However, there is little information on the health status of overweight and obese children in the community, who now represent a large proportion of the child population. We examined parent-reported child health and well-being and parent concern about child weight by body mass index (BMI) category in a population sample of primary school children.

Design: A stratified two-stage random cluster sample of 24 primary schools representative of the state of Victoria, Australia.

Measures: BMI (weight/height2) transformed to normalised Z-scores using the 1990 UK Growth Reference; the Child Health Questionnaire (CHQ), a 13-scale 50-item parent-completed measure of health and well-being; parent self-reported height and weight; parent concern about child's weight.

Results: Data were available for 2863 children aged 5-13 y (50.5% male), of whom 17% were overweight and 5.7% obese. Using logistic regression analyses with 'normal weight' as the referent category, obese boys were at greater risk of poor health (ie <15th centile) on seven of the 12 CHQ scales: Physical Functioning (odds ratio (OR) 2.8), Bodily Pain (OR 1.8), General Health (OR 3.5), Mental Health (OR 2.8), Self Esteem (OR 1.8), Parent Impact¾Emotional (OR 1.7) and Parent Impact¾Time (OR 1.9). Obese girls were at greater risk of poor health on only two scales: General Health (OR 2.1) and Self Esteem (OR 1.8). Forty-two percent of parents with obese children and 81% with overweight children did not report concern about their child's weight. Parents were more likely to report concern if the child was obese (OR 21.3), overweight (OR 3.5) or underweight (OR 5.4) than normal weight (P<0.05). Concern was not related to child gender, parental BMI or parental education after controlling for child BMI. Perceived health and well-being of overweight/obese children varied little by weight category of the reporting parent (overweight vs non-overweight).

Conclusions: Parents were more likely to report poorer health and well-being for overweight and obese children (particularly obese boys). Parental concern about their child's weight was strongly associated with their child's actual BMI. Despite this, most parents of overweight and obese children did not report poor health or well-being, and a high proportion did not report concern. This has implications for the early identification of such children and the success of prevention and intervention efforts.

Overweight and obesity from childhood to adulthood: a follow-up of participants in the 1985 Australian Schools Health and Fitness Survey

Objective: To examine overweight and obesity in Australian children followed through to adulthood.

Design and participants: A cohort study of 8498 children aged 7–15 years who participated in the 1985 Australian Schools Health and Fitness Survey; of these, 2208 men and 2363 women completed a follow-up questionnaire at age 24–34 years in 2001–2005.

Main outcome measures: Height and weight were measured in 1985, and self-reported at follow-up. The accuracy of self-reported data was checked in 1185 participants. Overweight and obesity in childhood were defined according to international standard definitions for body mass index (BMI), and, in adulthood, as a BMI of 25–29.9 and ≥ 30 kg/m2, respectively, after correcting for self-report error.

Results: In those with baseline and follow-up data, the prevalence of overweight and obesity in childhood was 8.3% and 1.5% in boys and 9.7% and 1.4% in girls, respectively. At follow-up, the prevalence was 40.1% and 13.0% in men and 19.7% and 11.7% in women. The relative risk (RR) of becoming an obese adult was significantly greater for those who had been obese as children compared with those who had been a healthy weight (RR = 4.7; 95% CI, 3.0–7.2 for boys and RR = 9.2; 95% CI, 6.9–12.3 for girls). The proportion of adult obesity attributable to childhood obesity was 6.4% in males and 12.6% in females.

Conclusion: Obesity in childhood was strongly predictive of obesity in early adulthood, but most obese young adults were a healthy weight as children.

Overweight, obesity and metabolic syndrome in rural south-eastern Australia

Aims & rationale/Objectives : To measure the prevalence of overweight, obesity and the metabolic syndrome in rural Australia.</p>

Methods :Two cross-sectional population surveys of chronic disease risk factors were carried out in rural Victoria (Corangamite Shire) and South Australia (Limestone Coast) in 2004-05. For both surveys, a stratified random sample of the population aged 25 to 74 years was drawn from the electoral roll. The surveys comprised a self-administered questionnaire, physical measurements and laboratory tests.</p>

Principal findings : A total of 841 individuals had complete questionnaire, health check and measured MetS data. The prevalence of overweight and obesity was 75% in males and 64.7% in females defined by BMI. Using waist circumference, the prevalence of overweight and obesity was higher in females (72.9%) than in males (63.2%). The overall prevalence of obesity of was 30.1% when defined by BMI, but 44.8% when defined by waist circumference. The prevalence of metabolic syndrome according to NCEP ATP III 2005 criteria was 29.0% in males and 28.5% in females. According to IDF criteria, the prevalence for males and females were 30.5% and 36.3%, respectively. The prevalence of metabolic syndrome and central (abdominal) obesity, hyperglycaemia, hypertension, and hypertriglyceridaemia increased with age.

Discussion : The prevalence of overweight and obesity, in particular central obesity, in rural Australia is very high as is the prevalence of metabolic syndrome.

Implications : Urgent population wide action is required to turn this trend around and regular monitoring of the trends in response to such action is essential.

Economic Evaluation of a Primary Care Trial to Reduce Weight Gain in Overweight/Obese Children: The LEAP Trial

Background:- A common policy response to the childhood obesity epidemic is to recommend that primary care physicians screen for and offer counseling to the overweight/obese. As the literature suggests, this approach may be ineffective; it is important to document the opportunity costs incurred by brief primary care obesity interventions that ultimately may not alter body mass index (BMI) trajectory.

Methods:- Live, Eat and Play (LEAP) was a randomized controlled trial of a brief secondary prevention intervention delivered by family physicians in 2002-2003 that targeted overweight/ mildly obese children aged 5 to 9 years. Primary care utilization was prospectively audited via medical records, and parents reported family resource use by written questionnaire. Outcome measures were BMI (primary) and parent-reported physical activity and dietary habits (secondary) in intervention compared with control children.

Results:- The cost of LEAP per intervention family was AU $4094 greater than for control families, mainly due to increased family resources devoted to child physical activity. Total health sector costs were AU $873 per intervention family and AU $64 per control, a difference of AU $809 {P < .001). At 15 months, intervention children did not differ significantly in adjusted BMI or daily physical activity scores compared with the control group, but dietary habits had improved.

Conclusions:- This brief intervention resulted in higher costs to families and the health care sector, which could have been devoted to other uses that do create benefits to health and/or family well-being. This has implications for countries such as the United States, the United Kingdom, and Australia, whose current guidelines recommend routine surveillance and counseling for high child BMI in the primary care sector.

Cost-effectiveness of a family-based GP-mediated intervention targeting overweight and moderately obese children

Objective
 To assess from a societal perspective the incremental cost-effectiveness of a family-based GP-mediated intervention targeting overweight and moderately obese children. The intervention was modelled on the LEAP (live, eat and play) trial, a randomised controlled trial conducted by the Centre for Community Child Health, Melbourne, Australia in 2002–2003. This study was undertaken as part of the assessing cost-effectiveness (ACE) in obesity project which evaluated, using consistent methods, 13 interventions targeting unhealthy weight gain in children and adolescents.
Method
A logic pathway was used to model the effects of the intervention compared to no intervention on body mass index (BMI) and health outcomes (disability-adjusted life years—DALYs). Disease costs and health benefits were tracked until the cohort of eligible children reached the age of 100 years or death. Simulation-modelling techniques were used to present a 95% uncertainty interval around the cost-effectiveness ratio. The intervention was also assessed against a series of filters (‘equity’, ‘strength of evidence’, ‘acceptability’, ‘feasibility’, sustainability’ and ‘side-effects’) to incorporate additional factors that impact on resource allocation decisions.
Results
The intervention, as modelled, reached 9685 children aged 5–9 years with a BMI z-score of ≥3.0, and cost $AUD6.3M (or $AUD4.8M excluding time costs). It resulted in an incremental saving of 2300 BMI units which translated to 511 DALYs. The cost-offsets stemming from the intervention totalled $AUD3.6M, resulting in a net cost per DALY saved of $AUD4670 (dominated; $0.1M) (dominated means intervention costs more for less effect).
Conclusion
Compared to a ‘no intervention’ control group, the intervention was cost-effective under current assumptions, although the uncertainty intervals were wide. A key question related to the long-term sustainability of the small incremental weight loss reported, based on the 9-month follow-up results for LEAP.

Double disadvantage : the influence of ethnicity over socioeconomic position on childhood overweight and obesity: findings from an inner urban population of primary school children

Objective: To examine the relationship between overweight/obesity in children, socioeconomic status and ethnicity/cultural background.

Design: Cross-sectional survey of children aged 4–13 years.

Setting: A total of 23 primary (elementary) schools in an inner urban municipality of Melbourne, Australia.

Participants: A total of 2685 children aged 4–13 years and their parents.

Main exposure measures: Ethnicity/cultural background – maternal region of birth; socioeconomic position (SEP) indicators – maternal and paternal educational attainment, family employment status, possession of a healthcare card, ability to buy food, indicator of disadvantage (Socioeconomic Index for Areas, SEIFA) score for school; parental weight status.

Main outcome measure: Prevalence of overweight/obesity.

Results: Prevalence of overweight/obesity approached 1 in 3 (31%) in this sample. Prevalence of overweight/obesity was greater for children of both North Africa and Middle Eastern background and children of Southern, South Eastern and Eastern European background compared with children of Australian background. This difference remained after adjusting for age, sex, height, clustering by school, SEP indicators and parental weight status; odds ratio, OR=1.57 (95% confidence interval, CI 1.12–2.19) and 1.88 (95%CI 1.24–2.85), respectively.

Conclusions: There is a clear independent effect of ethnicity above and beyond the effect of socioeconomic status on overweight and obesity in children. Further research is required to explore the mediators of this gradient.

A prospective examination of children's time spent outdoors, objectively measured physical activity and overweight

Objective: This study aimed to determine whether time spent outdoors was associated with objectively measured physical activity, body mass index (BMI) z-score and overweight in elementary-school aged children, cross-sectionally and prospectively over 3 years.
Methods: Three-year cohort study with data collected during 2001 and 2004. Nineteen randomly selected state elementary schools across Melbourne, Australia. One hundred and eighty eight 5–6-year-old and 360 10–12-year-old children. Baseline parent reports of children’s time spent outdoors during warmer and cooler months, on weekdays and weekends. At baseline and follow-up, children’s moderate and vigorous physical activity (MVPA) was objectively assessed by accelerometry, and BMI zscore and overweight was calculated from measured height and weight.
Results: Cross-sectionally, each additional hour outdoors on weekdays and weekend days during the cooler months was associated with an extra 27 min week^-1 MVPA among older girls, and with an extra 20 min week^-1 MVPA among older boys. Longitudinally, more time outdoors on weekends predicted higher MVPA on weekends among older girls and boys (5 min week^-1). The prevalence of overweight among older children at follow-up was 27–41% lower among those spending more time outdoors at baseline.
Conclusion: Encouraging 10–12-year-old children to spend more time outdoors may be an effective strategy for increasing physical activity and preventing increases in overweight and obesity. Intervention research investigating the effect of increasing time outdoors on children’s physical activity and overweight is warranted.

The provision of compulsory school physical activity : associations with physical activity, fitness and overweight in childhood and twenty years later

Background
To determine whether the provision of higher levels of compulsory school physical activity is associated with higher physical activity and fitness levels and less overweight in childhood and 20 years later.

Methods
As part of the 1985 Australian Schools Health and Fitness Survey, 109 schools reported how much compulsory physical education (PE) and school sport they provided and were classified as low (<110 and <150 minutes/week for primary and secondary schools, respectively), medium (110–149 and 150–189 minutes/week for primary and secondary schools, respectively) or high (≥150 and ≥190 minutes/week for primary and secondary schools, respectively) compulsory physical activity schools by tertile cutpoints. 6,412 children reported frequency and duration of school (PE and sport) and non-school (commuting and non-organised exercise) physical activity and had height and weight measured; overweight was defined using body mass index (BMI) (m/kg²) cutpoints. 9, 12 and 15 year-olds (n = 2,595) completed a cycle ergometer fitness test (physical working capacity at heart rate 170, PWC₁₇₀). At follow-up in 2004–5, 2,346 participants kept a pedometer record, completed the International Physical Activity Questionnaire and/or a PWC₁₇₀ fitness test; and had height and weight measured (overweight = BMI≥25 m/kg²).

Results
At baseline and follow-up, median total physical activity, fitness and BMI were similar in participants who attended low, medium and high physical activity schools, and those attending high physical activity schools reported only modestly higher school physical activity. There was no difference in the prevalence of high total physical activity and fitness levels in childhood or adulthood across compulsory school physical activity categories. The prevalence of overweight in childhood and adulthood was similar across low, medium and high compulsory physical activity schools.

Conclusion
The amount of compulsory physical activity reported by schools was not associated with total physical activity, fitness or overweight in childhood or in adulthood. Policies promoting amounts of compulsory school physical activity in this range may not be sufficient to increase physical activity and fitness or reduce the prevalence of obesity in children.

Overweight children have poor bone strength relative to body weight, placing them at greater risk for forearm fractures

Introduction: Obesity is thought to be a protective factor for bones in adults but not in children based on the evidence of the greater incidence of forearm fractures in obese children. Our objective was to investigate the effect of adiposity on bone strength in relation to the mechanical challenge placed onto the forearm bones in case of a fall.

Methods: Cross sectional areas (CSA) were obtained at the mid- and distal radius by peripheral quantitative computed tomography in 486 children (241 boys), mean age 8.3 years (range 6.9–9.7), participating in the LOOK Project. The following parameters were measured: bone mass and bone CSA (both sites), and muscle and fat CSA (mid-forearm only). Bone strength indices combining bone size and total volumetric density were calculated at each site.

Results/Discussion: Overweight children (BMI > percentile equivalent to 25 kg/m² in adults) have higher bone parameters than normal-weight peers (Z-scores +0.6 to +0.9SD, p < 0.0001). These differences disappear after adjustment for muscle CSA. Adiposity (fat CSA/muscle CSA) was negatively correlated with bone mass, size and strength at the distal radius only (r = −0.1, p < 0.05). After adjustment for body weight (estimate of the load during a fall), the negative correlations were stronger and observed at both the mid- and distal radius (r = −0.37 to −0.55, p < 0.0001).

Conclusion. Overweight children have stronger bones due to greater muscle size. However, children with high fat mass relative to muscle mass (increased adiposity) have poorer bone strength, independent of weight, which may contribute to the increased risk of fracture in obese children.