¹Centre for Community Child Health, Royal Children's Hospital, Melbourne, Australia

²Department of Paediatrics, Royal Children's Hospital, Melbourne, Australia

Correspondence to: M Wake, Director, Research and Public Health Unit, Centre for Community Child Health, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052, Australia. E-mail: wakem@cryptic.rch.unimelb.edu.au

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.

International Journal of Obesity (2002) 26, 717-724. DOI:10.1038/sj/ijo/0801974

child health status; obesity; overweight; body mass index; population survey; parent concern

Introduction

Childhood overweight/obesity is associated with a range of adverse health impacts that can affect children in the short and longer term. Most importantly, childhood obesity strongly predicts adult obesity, although the independent contribution of early obesity to adult obesity-associated morbidity and mortality is debated.^1,2 For individual children, immediate psychosocial effects of childhood obesity may include social isolation, discrimination, and peer problems in childhood.³ By adolescence lower self esteem,^4,5 associated with increased rates of sadness, loneliness and nervousness,⁶ have been reported. Common physical health problems with long-term implications include advanced growth, hyperlipidaemia and glucose intolerance, and there is a wide range of less common conditions. Despite measurement difficulties limiting research in this area, overweight/obesity has also been directly linked to a reduction in level and amount of physical activity^7,8 and participation in active sporting activities. With more than 20% of Australian primary school-aged children now overweight or obese,⁹ what are the impacts of overweight and obesity on child health at a population level.

There are a number of limitations with the current research literature in this area. Firstly, the available evidence is commonly derived from clinical rather than epidemiological samples, and at least one study has indicated a much lower level of psychological concern in a non-clinical than a clinical sample of obese children.¹⁰ Many overweight/obese children present to primary care or paediatric clinics with established co-morbidities, so that existing research may be heavily biased towards obese children with the most severe physical and/or mental health problems.¹⁰ Secondly, studies have tended to examine very specific issues (eg dietary fat, eating patterns and behaviours, self esteem, energy expenditure) hypothesised to be related to obesity. At a population level, adult obesity appears to be related to poorer self-reported general health, vitality and increased bodily pain as measured by general health measures such as the SF-36,¹¹ a widely used multi-dimensional adult measure of self-reported health and well-being. The impact of obesity on children's overall health and well-being, and/or health-related quality of life, or the well-being of their parents and families has not been well studied. The observation that many parents of obese young children may neither recognise nor feel concerned about a child's established weight problems^12,13 suggests that many parents may also not perceive an impact on their child's health and well-being. This is supported in at least one highly selected population comprising mainly overweight and obese children,¹⁴ and could have important implications for the uptake of prevention or intervention efforts.

With the advent of short, valid and reliable generic measures of child health and well-being suitable for use in large-scale epidemiological studies, it is now possible to assess health correlates of overweight/obesity for children in community settings. Typically, these instruments contain measures of physical, emotional and social health and well-being, and may also cover illness-related stress, social and behavioural functioning, and assessment of impact of the child's health on parent and family well-being.¹⁵ Such generic instruments are not designed to tap all domains that may be specifically related to obesity, but are able to give an overall picture of how parents perceive the health and well-being of their children across multiple dimensions of health.

A recent large epidemiologic survey of Australian primary school children provided an opportunity to examine relationships between parent perceptions of child health/well-being and overweight/obesity in a representative population sample. We hypothesised that parents would report poorer health and family functioning for overweight/obese children than for children of acceptable body mass index (BMI). We also explored parent concern about their child's weight, and whether perception of the health of their overweight child was related to parents' own BMI status.

Methods

This study was conducted within the Health of Young Victorians Study (HOYVS), a school-based epidemiological study of the health and well-being of children aged 5-18 y. Data were collected between July and December 1997 across the state of Victoria, Australia (population 4 689 800 in 1998¹⁶). A two-stage stratified random sampling design was used to draw the sub-sample of 24 primary schools. In the first stage schools were stratified by sector (government, Catholic and independent) and selected with a probability proportional to size. In the second stage, one intact class at each year level (preparatory¾grade 6) was randomly selected at each school to participate in the study (where the total school population was less than 240 students the entire school was sampled). Subjects were all HOYVS primary school children for whom complete height and weight information and parent questionnaires were available.

Using standard protocols based on the 1985 Australian Health and Fitness Survey,¹⁷ trained observers weighed and measured each participating child in light clothing without shoes. The portable rigid Invicta stadiometer was used to measure height. This instrument measures to the nearest 0.1 cm to 207 cm and needs no calibration.¹⁸ Regularly calibrated digital scales (Tanita model 1597) were used to measure weight. Calibration showed the scales to be reliable to the nearest 20 g. BMI was calculated as weight in kilograms divided by the square of height in meters (weight/height²).

Child BMI was transformed to standard deviation (Z) scores based on exact age using the British 1990 Growth Reference incorporating Cole's 'LMS' method to reduce right skew and adjust for physiological changes in BMI with age.¹⁹ Essentially, the Z-score represents a point on the 'normal' BMI distribution curve that corresponds to a specified cut-off point; for example, a Z-score of 1.0 would represent a BMI of one standard deviation above the mean in the population from which the scores were derived. Thus children were grouped into underweight, normal weight, overweight and obese categories using BMI Z-score cut-off points linked to BMI values of 18.5, 25 and 30 at age 18 for the UK reference population,²⁰ one of the six datasets contributing to new international cut-off points for children. This was used in preference to the six datasets combined because of the availability of software with which to calculate Z-scores based on exact age, rather than by fixed 6 month age brackets. Thus for boys, a Z-score <-1.22 was designated underweight,>1.3 to 2.37 overweight, and >2.37 obese, with normal weight categorised as -1.22 to 1.3. For girls, the Z-score values were <-1.17, >1.19 and >2.25, respectively. Although there is no evidence that thinness per se leads to morbidity in adults²¹ or children, anecdotally many parents are concerned about perceived underweight in young children and it thus seemed unwise to include very thin children in the 'normal weight' category. Meaningful BMI cut-off points for child underweight have yet to be defined and their short and long-term relationships with child health status studied; the selected cut-off point reflects one suggested criterion for adults.²¹

The Child Health Questionnaire,²² a multi-dimensional, generic measure of child health and well-being, was completed at home by a parent/guardian of each child. The parent-report version (CHQ-PF50) comprises 50 items from which are derived two single and 11 multi-item scales that tap concepts contributing to overall functioning and well-being of children in the context of their family and social environments (see Table 1 for description of scales). Scales are transformed to a range of 0-100, with the highest score (100) assigned to the best possible health and the lowest score (0) to the poorest possible health. Time referenced scales are based on a 4-week recall, with the exception of the Change in Health scale, which is based on the past year and was not included in the analysis for this paper. Population data and psychometric properties are available for Australian children aged 5-18 y.^22,23 However, the available Physical and Psychosocial Summary scores were not used since prior analysis did not support their psychometric validity in this population based sample.²³

Parents also answered a single yes/no question ('Are you concerned about your child's weight?'), reported the height and weight of the child's biological parents, and provided socio-demographic information.

The statistical packages SPSS for Windows (Release 6.1)²⁴ and Stata (Version 5.0)²⁵ were used for all analyses. Because of marked left skew on some of the CHQ scales, ranked scores for each CHQ scale were compared for each BMI category using the Kruskal-Wallis test. Logistic regression was used to examine the odds of children in different BMI categories differing in parent-reported health, using 'normal weight' as the referent category. The 15th centile of observed responses for each scale was used to differentiate children with significantly worse health (those with responses below the 15th centile value for each scale) from those with better health (the remainder) in this largely healthy population. The 15th centile falls just below the parametric concept of one standard deviation below the mean, and avoided all ceiling effects. Finally, for each scale we calculated the relative risk of overweight/obese children (dichotomised; BMI Z-score equivalent >25) being in 'poor health' if their responding parent was also overweight/obese (dichotomised; BMI >25, calculated from respondent self-reported height and weight).

Previous analyses of this dataset have shown slight differences in CHQ scores by child gender and age.²³ In addition, mothers reported child health status differently from fathers,²⁶ a possible source of bias since families were free to choose which parent completed the questionnaire. Therefore all analyses were conducted for males and females separately, and multivariate analyses were also adjusted for gender of reporting parent and age of child. Since we wished to examine parent perceptions of health status we did not adjust for other demographic variables which reflected the diversity of this population-representative sample even when they may have influenced BMI.

Ethics approval for the study was obtained from the Royal Children's Hospital Ethics in Human Research Committee. Informed consent was obtained from a parent or guardian for each participant.

Results

A total of 3174 primary school children participated in HOYVS (75% response), with BMI-related questionnaire and measurement data available for 2863 children (50.5% male). Classifications were 4.4, 72.8, 17.0 and 5.7% as underweight, normal weight, overweight and obese, respectively (see Table 2 for breakdown for boys and girls separately). Sociodemographic sample characteristics of the sample are presented in Table 2.

Ranked CHQ scale scores for parent-reported child health generally differed little when compared across the four BMI categories using the Kruskal-Wallis test. For some scales this may have been due to the very high proportion of ceiling scores. For boys, significant rank differences by BMI category were seen for only three scales (Physical Functioning (P=0.01), Self Esteem (P=0.01) and General Health (P=0.0001)). For girls, significant differences were seen for only two scales (General Health (P=0.001) and Self Esteem (P=0.01)). Box and whisker plots by weight category for these scales are presented graphically in Figure 1. For boys, the median for the Physical Functioning scale was 100 for all BMI groups, and the significant rank difference is due to the lower tail of the distribution in the obese category.

Table 3 presents logistic regression analyses with 95% confidence intervals for parent-reported health of boys and girls separately. There was a significantly greater likelihood of parent scores for obese boys falling below the 15th centile on seven of the 12 scales: Physical Functioning (OR 2.8), Bodily Pain (OR 1.8), Mental Health (OR 2.8), Self Esteem (OR 1.8), General Health (OR 3.5), Parent Impact¾Emotional (OR 1.7) and Parent Impact¾Time (OR 1.9). In addition, low scores were more likely for overweight than normal weight boys on the Role/Social-Physical (OR 1.5) and Mental Health (OR 1.7) scales. Low scores for obese compared to normal weight girls were significantly more likely on only two scales, Self Esteem (OR 1.8) and General Health (OR 2.1), and for overweight girls on the Role/Social-Emotional and Self Esteem scales (OR 1.5 and 1.8 respectively). While not the focus of this report, we also note that underweight girls were more likely to receive low scores on four scales (Physical Functioning, OR 1.9; Role/Social-Physical, OR 1.9; General Health, OR 2.2; and Parent Impact¾Emotional, OR 1.8), and underweight boys on the Bodily Pain scale (OR 2.1).

In general, overweight/obese parents did not appear to view the health of their overweight/obese children differently from non-overweight parents of overweight/obese children, with two exceptions. Overweight/obese daughters of overweight/obese parents were more likely to receive poor Mental Health scores (RR 1.8, 95% CI 1.0, 3.2, P=0.04), while overweight/obese sons were more likely to receive poor Physical Functioning scores (RR 1.7, 95% CI 1.0, 2.9, P=0.04).

Overall, only 12% of parents were concerned about their child's weight. Figure 2 shows that concern was more likely if the child was obese (OR 21.3), overweight (OR 3.5) or underweight (OR 5.4) than normal weight (P<0.05). Child gender, parental BMI and parental education were not related to the presence of concern after controlling for child BMI. Forty-two percent of parents with obese children, 81% with overweight children and 70% with underweight children did not report concern. Parental BMI, parental education and child gender did not distinguish 'unconcerned' from 'concerned' parents for obese, overweight or underweight children.

Discussion

Some important differences were found between parent-reported health of overweight/obese boys and boys of normal weight, whereas few differences were noted for girls. General health was the only domain for which parents reported poorer health for obese children of both genders. However, the magnitude of differences was generally small and no significant impact was evident on many of the domains; the majority of overweight and obese children were rated as being as healthy as their normal weight peers. These results support the proposition that parents of obese children in the community are less likely to report adverse effects in community samples than in clinically derived samples. In general, parents of overweight/obese children differed little in their perception of their child's weight or health according to their own BMI status.

We also note a low level of parent-reported concern about their child's weight. This finding is consistent with a number of recent published reports across a range of populations of varying age groups and using slightly different questions to probe parent awareness and concern.^12,,14,27

A number of possible limitations need to be discussed. Most importantly, several factors might have lead to an underestimation of the effects of underweight and overweight/obesity on health and well-being. Firstly, overweight or obese children with poorer health or well-being may have been less likely to participate in the study, leading to underestimation of health effects. However, this study was not primarily directed at obese children and field researchers did not observe any apparent lack of willingness to take part among heavier children. Secondly, high ceiling effects on scales measuring physical functioning, social roles and impact on parent time may have lessened the ability of the CHQ to discriminate true differences between normal weight children and those at extremes of BMI. Future research using measures with more extreme and fine-grained upper ranges in physical functioning, possibly based on physical fitness levels or children's ideals of functioning, might give us a better indication of whether obese, overweight and underweight children are more limited than this study suggests. Having said this, the CHQ has been shown to reveal marked health deficits in samples of children in the community with conditions such as diabetes who do not appear overtly unwell to their clinicians.²⁸ Thirdly, the CHQ may not identify specific impacts of underweight and obesity that are important to parents and children, such as issues relating directly to body self image. Nonetheless, it should give a good general picture of parent-perceived impact of overweight/obesity on children in the community on a broad range of functional health domains important to everyday well-being. Ideally, a measure such as the CHQ would be used in conjunction with an obesity-specific measure, to capture both general domains of health and those specific to obesity and overweight.

We obtained information only from parents, and not from children themselves. Children are known to report their own health-related quality of life differently than their parents, although this information has largely been derived in the context of chronic illness.^3,29 Children's own subjective response to overweight and obesity might be more negative than and qualitatively different from that of their parents. This will be an important area of further research as better measures suitable for younger children become available. Even so, our findings have important implications. It is likely that parents are the chief initiators of clinical consultation for primary school aged children; if parents do not perceive a problem, then it is unlikely that they will seek help for their child's weight.

The response rate of 75%, although respectable for school based studies requiring informed consent, may limit our ability to generalise findings to groups which may have been under-represented, particularly children born to parents with poor literacy or those with non-English-speaking backgrounds.

These results have both positive and negative implications. At a population level, large numbers of overweight/obese children, particularly boys, are experiencing limitations to their general health, physical functioning, psychosocial well-being and family relationships. We urgently need effective interventions to help these children. However, many overweight and obese children do not seem to suffer general adverse health effects of concern to their parents. On the one hand this can be seen positively, since ideally all children with chronic conditions (including obesity) would enjoy the same quality of life as their healthy peers. On the other hand, if parents do not perceive a health impact or feel concerned, it seems unlikely that they would seek health care for their child's weight. Does this matter? Treatment for child obesity can be partially effective in carefully controlled settings,³⁰ but there is no evidence that healthcare directed at individuals has yet had any effect in terms of altering population trends towards increased obesity. Population strategies may be a more effective approach, particularly if they are multidimensional (for example, combine social behavioural strategies, psychological theory, physical activity and nutritional initiatives) and set within the context of current community- or school-based activities.³¹ Important recent studies indicate that such approaches may be worthwhile,³¹ although we do not yet know if these programmes will prove to be sustainable.

To better understand the full impact of child overweight/obesity in the community, research aimed specifically at clarifying parents' and children's perspectives about child weight and its impact on children's short- and long-term health is needed. This might shed further light on aspects of child overweight/obesity that do concern parents in the community, which might lead to new intervention strategies.

Acknowledgements

We would like to acknowledge the Victorian Department of Human Services Division of Public Health for providing funding for the project, Dr Rory Wolfe for providing statistical consultation to the paper, and Dr Malcolm Rosier for providing statistical consultation to the study. We thank Lisa Templeton and John Birchall for assisting with field work.

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Figure 1 Box and whisker plots for CHQ sclaes on which the Kruskal Wallis test indicated significant rank differences by weight category (for boys: General Health, Self Esteem and Physical Functioning; for girls: General Health and Self Esteem). Note that because of the large ceiling effect, the median for the Physical Functioning scale for boys is 100 in all weight categories, and the significant rank difference is due to the lower tail of the distribution in the obese category.

Figure 2 Proportion of parents reporting concern about child's weight, by child BMI category.

Table 1 Description of scales in the CHQ-PF50

Table 2 Characteristics of the sample (n=2863)

Table 3 Odds ratios (OR) for 'poorer health' on CHQ scales as a function of BMI category