Meta-Analysis of the Association between Body Mass Index and Health-Related Quality of Life among Children and Adolescents, Assessed Using the Pediatric Quality of Life Inventory Index Zia Ul-Haq, MBBS, MPH, Daniel F. Mackay, PhD, Elisabeth Fenwick, PhD, and Jill P. Pell, MBChB, MD Objective To explore the relationships between body mass index and overall, physical, and psychosocial health- related quality of life (HRQoL) in children and adolescents. Study design A systematic review was conducted in accordance with Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Medline, Embase, PsycINFO, and the Web of Knowledge were searched for relevant articles. Inclusion was restricted to participants under 20 years of age, assessed using the Pediatric Quality of Life Inventory. Random-effects meta-analysis, meta-regression, and cumulative meta-analysis were conducted. Heterogeneity was assessed using the I 2 statistic, and potential publication and small study bias were evaluated using funnel plots and the Egger test. Results Eleven eligible studies provided 35 estimates of effect size, derived from a total of 13 210 study partici- pants. Based on self-reports, children and adolescents with above-normal body mass index had significantly lower total, physical, and psychosocial HRQoL, with a clear dose relationship across all categories. In obese children and adolescents, the overall score was reduced by 10.6 points (95% CI, 14.0-7.2; P < .001). Parents reported the same pattern but a larger effect size. The total parental score for obese children and adolescents was reduced by 18.9 points (95% CI, 26.6-11.1; P < .001). No significant publication or small study bias was observed. Conclusion Parents overestimate the impact of obesity on the HRQoL of their children. Nonetheless, obese children and adolescents have significantly reduced overall, physical, and psychosocial HRQoL. (J Pediatr 2013;162:280-6). R ecent estimates suggest that worldwide, approximately 43 million children under age 5 years are overweight, including 35 million in developing countries and 8 million in developed countries. 1 The prevalence of overweight and obesity in children and adolescents is increasing. 2-4 Obesity in childhood predisposes to obesity in adulthood, which in turn in- creases the risk of poor health and reduced life expectancy. 5,6 The relationship between adult obesity and health-related quality of life (HRQoL) is complex. Physical HRQoL demonstrates a dose relationship, decreasing steadily with increasing body mass index (BMI) from the normal range to obese. 7,8 In contrast, mental HRQoL is significantly reduced in obese adults, but not in overweight adults. 7 The relationship between childhood obesity and HRQoL is unclear. Previous studies using a mixture of self and parental reporting have yielded conflicting results. A systematic review published in 2009 9 suggested that HRQoL improves with weight loss, and pooled regression analyses showed that pediatric HRQoL can be predicted from parent proxy reports, even though parents tend to perceive worse HRQoL than children. 9 No meta-analysis has been reported to date. We undertook an updated systematic review and meta-analysis of published studies to examine the associations between childhood/adolescent BMI and overall, physical, and psychosocial HRQoL, and to determine whether parental perceptions of impact differ from the children’s self-reports. Methods We performed a systematic review of published articles in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines (http://www.prisma-statement.org/). The relevant search terms ("obes * " or "BMI" or "body mass index" or "overweight") and ("HRQoL" or "quality of life" or "QoL") were applied to 4 electronic databases: Embase, Medline, ISI Web of Knowledge, and PsycINFO. The last search was undertaken on August 1, 2011. The electronic search was limited to studies conducted on humans and written in, or translated into, English. The identified articles were then reviewed manually, and their reference lists checked for any additional relevant studies. Articles reporting studies conducted in children and or adolescents, defined as From the Institute for Health and Wellbeing, University of Glasgow, Glasgow, United Kingdom Z.U.-H. is sponsored by the Higher Education Commission, Pakistan (Development of Khyber Medical University, Peshawar). The authors declare no conflicts of interest. 0022-3476/$ - see front matter. Copyright ª 2013 Mosby Inc. All rights reserved. http://dx.doi.org/10.1016/j.jpeds.2012.07.049 BMI Body mass index HRQoL Health-related quality of life PedsQL Pediatric Quality of Life Inventory PRISMA Preferred Reporting Items for Systematic Review and Meta-Analysis 280
Transcript
Meta-Analysis of the Association between Body Mass Index andHealth-Related Quality of Life among Children and Adolescents,Assessed Using the Pediatric Quality of Life Inventory Index
Zia Ul-Haq, MBBS, MPH, Daniel F. Mackay, PhD, Elisabeth Fenwick, PhD, and Jill P. Pell, MBChB, MD
Objective To explore the relationships between body mass index and overall, physical, and psychosocial health-related quality of life (HRQoL) in children and adolescents.Study design A systematic review was conducted in accordance with Preferred Reporting Items for SystematicReview and Meta-Analysis guidelines. Medline, Embase, PsycINFO, and the Web of Knowledge were searched forrelevant articles. Inclusion was restricted to participants under 20 years of age, assessed using the Pediatric Qualityof Life Inventory. Random-effects meta-analysis, meta-regression, and cumulative meta-analysis were conducted.Heterogeneity was assessed using the I2 statistic, and potential publication and small study bias were evaluatedusing funnel plots and the Egger test.Results Eleven eligible studies provided 35 estimates of effect size, derived from a total of 13 210 study partici-pants. Based on self-reports, children and adolescents with above-normal body mass index had significantly lowertotal, physical, and psychosocial HRQoL, with a clear dose relationship across all categories. In obese children andadolescents, the overall score was reduced by 10.6 points (95% CI, 14.0-7.2; P < .001). Parents reported the samepattern but a larger effect size. The total parental score for obese children and adolescents was reduced by 18.9points (95% CI, 26.6-11.1; P < .001). No significant publication or small study bias was observed.Conclusion Parents overestimate the impact of obesity on the HRQoL of their children. Nonetheless, obesechildren and adolescents have significantly reduced overall, physical, and psychosocial HRQoL. (J Pediatr2013;162:280-6).
Recent estimates suggest that worldwide, approximately 43 million children under age 5 years are overweight, including35 million in developing countries and 8 million in developed countries.1 The prevalence of overweight and obesity inchildren and adolescents is increasing.2-4 Obesity in childhood predisposes to obesity in adulthood, which in turn in-
creases the risk of poor health and reduced life expectancy.5,6 The relationship between adult obesity and health-related qualityof life (HRQoL) is complex. Physical HRQoL demonstrates a dose relationship, decreasing steadily with increasing body massindex (BMI) from the normal range to obese.7,8 In contrast, mental HRQoL is significantly reduced in obese adults, but not inoverweight adults.7 The relationship between childhood obesity and HRQoL is unclear. Previous studies using a mixture of selfand parental reporting have yielded conflicting results. A systematic review published in 20099 suggested that HRQoL improveswith weight loss, and pooled regression analyses showed that pediatric HRQoL can be predicted from parent proxy reports,even though parents tend to perceive worse HRQoL than children.9 Nometa-analysis has been reported to date. We undertookan updated systematic review andmeta-analysis of published studies to examine the associations between childhood/adolescentBMI and overall, physical, and psychosocial HRQoL, and to determine whether parental perceptions of impact differ from thechildren’s self-reports.
BMI Body mass index
HRQoL Health-related quality of lif
PedsQL Pediatric Quality of Life Inv
PRISMA Preferred Reporting Items
280
Methods
We performed a systematic review of published articles in accordance with the Preferred Reporting Items for Systematic Reviewand Meta-Analysis (PRISMA) guidelines (http://www.prisma-statement.org/). The relevant search terms ("obes*" or "BMI" or"bodymass index" or "overweight") and ("HRQoL" or "quality of life" or "QoL") were applied to 4 electronic databases: Embase,Medline, ISI Web of Knowledge, and PsycINFO. The last search was undertaken on August 1, 2011. The electronic search waslimited to studies conducted on humans and written in, or translated into, English. The identified articles were then reviewed
manually, and their reference lists checked for any additional relevant studies.Articles reporting studies conducted in children and or adolescents, defined as
From the Institute for Health and Wellbeing, University ofGlasgow, Glasgow, United Kingdom
Z.U.-H. is sponsored by the Higher EducationCommission, Pakistan (Development of Khyber MedicalUniversity, Peshawar). The authors declare no conflictsof interest.
0022-3476/$ - see front matter. Copyright ª 2013 Mosby Inc.
All rights reserved. http://dx.doi.org/10.1016/j.jpeds.2012.07.049
age <20 years, were included in the meta-analysis. The Pedi-atric Quality of Life Inventory (PedsQL) was the most fre-quently used index. Therefore, inclusion criteria for themeta-analysis were limited to studies that used the PedsQLand reported overall, physical, and psychosocial summaryscores. PedsQL is a generic HRQoL index developed forself-reporting by study participants aged 5-18 years and forparent proxy reporting for participants aged 2-18 years.10,11
It comprises 23 items that encompass physical, emotional,social, and school functioning and produces standardizedscores for overall, physical, and psychosocial HRQoL rangingfrom 0 to 100, with higher scores indicating betterHRQoL.10,12 BMI was categorized using the InternationalObesity Task Force age- and sex-specific BMI cutoff values13
into normal weight, overweight, obese, and severely obese.For studies that used the Centers for Disease Control andPrevention definition, we treated the normal weight, at riskfor overweight, overweight, and very overweight as equiva-lent to these 4 International Obesity Task Force categories.14
The information collated from individual studies includedstudy design, age, sex, region, year of publication, numberof participants, and mean � SD PedsQL score by BMI cate-gory. No additional individual-level data were obtained fromthe study investigators.
We conducted a random-effects meta-analysis of theweighted mean differences in PedsQL scores for each BMIcategory compared with normal-weight subjects. I2 statisticswere calculated to assess the degree of heterogeneity.15 Weevaluated for possible publication and small study bias visu-ally, using funnel plots of weighted mean differences againsttheir standard errors, and then formally using the Eggertest.16 Potential sources of between-study heterogeneitywere investigated via univariate and multivariate meta-regression models17 with multiplicity-adjusted Monte Carlosimulations using 20 000 permutations. A cumulative meta-analysis was performed to explore changes over time in thepooled estimate of effect size,18 and a meta-influence graphwas produced to determine whether any individual studieshad a large influence on the pooled estimate. All statisticalanalyses were performed using Stata version 11.2 (StataCorp,College Station, Texas).
Results
Our electronic search of the 4 databases identified 968 poten-tially eligible studies, of which 460 were excluded as dupli-cates. An additional 32 articles were identified from thereference lists (Figure 1; available at www.jpeds.com). Areview of abstracts of the resulting 540 articles identified74 studies considered relevant, and those complete articleswere studied. Fifty-two studies did not meet our inclusioncriteria. Of the 22 studies that used the PedsQL index,only 11 provided the overall, physical, and psychosocialsummary scores by BMI category and thus were includedin the meta-analysis. The 11 studies included a total of13 210 children and/or adolescents (a range of 93 to 5543participants per study), of whom 1370 (10%) were either
Figure 2. Forest plots of the child-self reports from the obese participants compared with normal-weight participants. A, Totalscore. B, Physical summary. C, Psychosocial summary. WMD, weighted mean difference.
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Table II. Pooled estimates of the WMD in HRQoL scores in obese and overweight compared with normal-weightchildren and adolescents
Child-self report Parent proxy report
Pooled estimate Heterogeneity Pooled estimate Heterogeneity
WMD (95% CI) P value I 2, % P value WMD (95% CI) P value I 2, % P value
ObeseTotal score �10.63 (�14.03 to �7.24) <.001 87.1 <.001 �18.87 (�26.60 to �11.14) <.001 96.3 <.001Physical summary �11.93 (�15.13 to �8.74) <.001 81.8 <.001 �21.73 (�30.12 to �13.35) <.001 95.4 <.001Psychosocial summary �9.99 (�13.98 to �6.01) <.001 88.1 <.001 �17.37 (�25.89 to �8.85) <.001 96.4 <.001
OverweightTotal score �1.43 (�2.55 to �0.32) .012 0 .690 �2.60 (�4.00 to �1.19) <.001 0 .322Physical summary �1.47 (�2.67 to �0.28) .015 4.4 .351 �4.16 (�6.57 to �1.74) .001 45.1 .177Psychosocial summary �1.15 (�2.46 to 0.16) .084 0 .774 �1.32 (�2.79 to 0.16) .080 0 .748
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overweight or obese. All 11 studies were published between2003 and 2011 (Table I). Five (45%) were conducted inNorth America,12,19-22 3 (27%) in Europe,23-25 2 (18%) inAustralia,26,27 and 1 (9%) in Asia.28 Nine studies werecross-sectional,12,19-21,23-26,28 and 2 were cohort studies.21,27
All studies included both sexes and all reported resultsobtained from child self-assessments. Eight of the studiesalso reported results obtained from parent proxyassessment.12,19-22,24,26,27 The location, year of publication,and study design were not significantly associated witheffect size on univariate or multivariate meta-regressionanalyses.
The 11 studies provided 35 estimates of the effect of obe-sity, 28 of which achieved statistical significance (Figure 2).Three studies provided 9 estimates of the effect ofoverweight, 1 of which achieved statistical significance.Compared with normal-weight children, obese childrenhad significantly lower overall HRQoL, as well assignificantly lower physical and psychosocial HRQoL(Table II). In relation to overall HRQoL, there was a cleardose relationship, with overall HRQoL reduced slightly inoverweight children and much more strongly in obesechildren (Table II). Similar patterns were observed forboth physical and psychosocial HRQoL, although thereduction in psychosocial HRQoL in overweight childrendid not reach statistical significance. The reduction inphysical HRQoL was slightly greater than that inpsychosocial HRQoL, but again the difference was notstatistically significant. Visual inspection of the funnel plotsdid not suggest asymmetry, and the Egger test producedstatistically nonsignificant results for all domains.Assessment using cumulative meta-analysis graphs showedthat the pooled estimates of effect size remained relativelyconstant over time. In the meta-influence plots, noindividual study had a disproportionately large effect onthe pooled estimate.
Eight studies provided 23 estimates of the effect of obesity,22 of which achieved statistical significance (Figure 3). Twostudies provided 6 estimates of the effect of being overweight,2 of which achieved statistical significance. Consistent withthe children’s self-reports, the parents of obese children
Meta-Analysis of the Association between Body Mass Index andand Adolescents, Assessed Using the Pediatric Quality of Life Inv
reported significantly reduced overall, physical, andpsychosocial HRQoL in their children (Table II). Therewas a dose effect in which HRQoL was reduced inoverweight children but to a much lesser extent than inobese children (Table II). As with the children’s self-reports, the reduction in psychosocial HRQoL reported bythe parents of overweight children did not reach statisticalsignificance. Across all 3 measures, parents consistentlyrated their overweight and obese children as suffering greaterreductions in HRQoL than those reported by the childrenthemselves. Compared with children, parents tended toreport a greater reduction in physical compared withpsychosocial HRQoL for both overweight and obesechildren; however, the differences were not statisticallysignificant. There was no evidence of asymmetry in thefunnel plots and results of the Egger test were not statisticallysignificant for any domain. The pooled estimates of effectremained relatively constant over time in the cumulativemeta-analysis graphs, and no individual study hada disproportionately large effect in the meta-influence plots.
Discussion
The evidence from previous studies suggests that obese chil-dren and adolescents have significantly reduced overallHRQoL. The impact on physical HRQoL is not significantlygreater than the impact on psychosocial HRQoL, but bothdomains are significantly reduced. Parents tend to overesti-mate the extent to which their children’s HRQoL is reduced;nonetheless, a significant effect is evident when based onchild self-reports. There is also evidence of a dose relation-ship in which HRQoL decreases as BMI increases from nor-mal weight, through overweight to obesity.Childhood obesity is significantly associated with various
morbidities,29 including non–insulin-dependent diabetesmellitus,30 hypertension,31 dyslipidemia,32 sleep apnea,33
gall bladder diseases,34 and depression.21 There has beenone previous systematic review of the effect of childhoodBMI on HRQoL,9 but to the best of our knowledge, this isthe first meta-analysis conducted in children. In a previousmeta-analysis of adults,7 we found a similar dose
Health-Related Quality of Life among Childrenentory Index
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Figure 3. Forest plots of the parent proxy reports from the obese participants compared with normal-weight participants.A, Total score. B, Physical summary. C, Psychosocial summary.
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relationship, with decreasing physical HRQoL with increas-ing BMI above normal weight. Psychosocial HRQoL was sig-nificantly reduced only in morbidly obese adults, however; itwas not significantly reduced in obese adults, and was signif-icantly increased in overweight adults.7 In contrast, psycho-social HRQoL was significantly reduced in obese childrenand nonsignificantly reduced in overweight children. Thissuggests that the psychosocial sequelae of increased BMImay be greater in children than in adults.
Parental overestimation of the adverse effect on HRQoL isnot restricted to obesity. Previous studies have shown that par-ents overestimate the adverse effect onHRQoL of other condi-tions, including cystic fibrosis.35,36 Why parents overestimatethe impact of childhoodobesity is not known, but contributingfactorsmay includeparental distress37 and greater awareness offuture complications.38 In contrast, children have a moreshort-term perspective.39 Moreover, the parents of obese chil-dren are more likely to be obese themselves,40 and their ownexperiences of being obese may affect their reporting.
Our meta-analysis was conducted in accordance withPRISMA guidelines, and 4 major databases were searchedto ensure that all relevant studies were identified. Thepooled estimates were derived from 11 studies that includeda total of 13 210 study participants. The majority of the in-dividual studies were cross-sectional, which are inferior tocohort studies in inferring causality. The included studieswere conducted on both clinical and community-basedsamples. Although the former might be expected to overes-timate the association, previous studies have demonstratedno significant differences in HRQoL between the 2 groups.28
We found no evidence of significant publication or smallstudy bias, but because the individual studies were not con-ducted under identical conditions, we used the more con-servative approach of random-effects meta-analysis. Weused the published results from individual studies,and did not approach the investigators for access toindividual-level data.
Overweight children are more likely to develop into over-weight adults5 and are at increased risk for many conditions.Our study suggests that they also suffer from impairedHRQoL. Thus, childhood obesity is an important publichealth problem, and effective interventions are urgentlyneeded to address the increasing prevalence. Our findingswill enable clinicians, public health physicians, and othersto educate children and their parents about the potential ad-verse effect of obesity on their HRQoL. n
Submitted for publication Apr 2, 2012; last revision received May 22, 2012;
accepted Jul 24, 2012.
Reprint requests: Jill P. Pell, MBChB, MD, Henry Mechan Professor of Public
Health, Institute for Health and Wellbeing, University of Glasgow, Room 305, 1
Webber LS, et al. Body fatness and risk for elevated blood pressure, total
cholesterol, and serum lipoprotein ratios in children and adolescents.
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33. Riley DJ, Santiago TV, Edelman NH. Complications of obesity-
hypoventilation syndrome in childhood. Am J Dis Child 1976;130:
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34. Acalovschi MV, Blendea D, Pascu M, Georoceanu A, Badea RI,
Prelipceanu M. Risk of asymptomatic and symptomatic gallstones in
moderately obese women: a longitudinal follow-up study. Am J Gastro-
enterol 1997;92:127-31.
35. Modi AC, Quittner AL. Validation of a disease-specific measure of
health-related quality of life for children with cystic fibrosis. J Pediatr
Psychol 2003;28:535-45.
36. Verrips GH, Vogels AG, den Ouden AL, Paneth N, Verloove-
Vanhorick SP. Measuring health-related quality of life in adolescents:
agreement between raters and between methods of administration.
Child: Care Health Dev 2000;26:457-69.
37. Vance YH,Morse RC, JenneyME, Eiser C. Issues in measuring quality of
life in childhood cancer: measures, proxies, and parental mental health. J
Child Psychology Psychiatry 2001;42:661-7.
38. Ingerski LM, Janicke DM, Silverstein JH. Brief report. Quality of life in
overweight youth: the role of multiple informants and perceived social
support. J Pediatr Psychol 2007;32:869-74.
39. Eiser C, Morse R. Can parents rate their child’s health-related quality of
life? Results of a systematic review. Qual Life Res 2001;10:347-57.
40. Lake JK, Power C, Cole TJ. Child to adult body mass index in the 1958
British birth cohort: associations with parental obesity. Arch Dis Child
1997;77:376-81.
Ul-Haq et al
Records screened N=540
Records excludedN=466
Additional records identified through other sources
N=32
Records after removal of duplicates N=540
Records identified through database (Medline, Embase Ps ycInFO, ISI Web
of Knowledge) N=968
Full-text articles assessed for eligibility
N=74
Studies used in qualitative review (used PedsQL)
N=22
Full-text articles excluded42 – adults
1 – review articles
9 – not PedsQL
Studies included in meta-analysis
N=11
(provided total, physical, and psychosocial summary
scores)
Iden
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atio
nSc
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Elig
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Figure 1. PRISMA flowchart.
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Meta-Analysis of the Association between Body Mass Index and Health-Related Quality of Life among Childrenand Adolescents, Assessed Using the Pediatric Quality of Life Inventory Index
