Annals of Tropical Medicine and Public Health

ORIGINAL ARTICLE
Year
: 2017  |  Volume : 10  |  Issue : 6  |  Page : 1814--1819

A comparison of the 2015 Indian Academy of Pediatrics, International Obesity Task Force and World Health Organization growth references among 5–18-year-old children


Inaamul Haq1, Malik Waseem Raja1, Mir Mujtaba Ahmad2,  
1 Department of Community Medicine, Government Medical College, Srinagar, Jammu and Kashmir, India
2 Department of General Surgery, Government Medical College, Srinagar, Jammu and Kashmir, India

Correspondence Address:
Inaamul Haq
Department of Community Medicine (SPM), Government Medical College, Srinagar - 190 010, Jammu and Kashmir
India

Abstract

Background and Rationale: The Indian Academy of Pediatrics (IAP) Growth Charts Committee has constructed revised IAP growth references for 5–18-year-old Indian children. This study was conducted with the objective of comparing these growth references with those prescribed by the International Obesity Task Force (IOTF) for Asian population and by the World Health Organization (WHO). Methods: Information about age, weight, and height was obtained from school-age children and adolescents between 5 and 18 years of age attending a health center as patients or accompanying persons. Three reference systems - the new IAP, “Asian” IOTF, and WHO-based on age- and gender-specific body mass index cutoffs were used to classify children as obese, overweight, or nonobese nonoverweight. The three reference systems were compared using weighted kappa. Results: The prevalence of overweight using new IAP, “Asian” IOTF, and WHO reference systems was 6.6%, 6.6%, and 4.0%, respectively. The prevalence of obesity using new IAP, “Asian” IOTF, and WHO reference systems was 5.0%, 5.0%, and 4.3%, respectively. The prevalence of overweight and obesity was lower when the WHO reference was used, especially for adolescents. There was an excellent agreement between new IAP and “Asian” IOTF references (weighted kappa = 0.9558, 95% confidence interval 0.9134–0.9982). Conclusions: The WHO reference may be less suitable for use in the Indian context, especially in adolescents.



How to cite this article:
Haq I, Raja MW, Ahmad MM. A comparison of the 2015 Indian Academy of Pediatrics, International Obesity Task Force and World Health Organization growth references among 5–18-year-old children.Ann Trop Med Public Health 2017;10:1814-1819


How to cite this URL:
Haq I, Raja MW, Ahmad MM. A comparison of the 2015 Indian Academy of Pediatrics, International Obesity Task Force and World Health Organization growth references among 5–18-year-old children. Ann Trop Med Public Health [serial online] 2017 [cited 2019 Aug 22 ];10:1814-1819
Available from: http://www.atmph.org/text.asp?2017/10/6/1814/222726


Full Text



 Introduction



The World Health Organization (WHO) defines overweight and obesity as “abnormal or excessive fat accumulation that may impair health.”[1] Childhood obesity and overweight are known to have both short- and long-term health consequences and a higher likelihood of developing noncommunicable diseases such as diabetes and cardiovascular diseases at a younger age.[2] Body mass index (BMI) the most widely used tool for the diagnosis of overweight and obesity, does not have similar cutoffs for children and adolescents as adults, because there is a considerable change in BMI with age.[3] Reference curves for the children and adolescents giving BMI distribution for age and sex have thus been developed for international use by the WHO [4] and the International Obesity Task Force (IOTF).[5] The WHO reconstructed the 1977 NCHS/WHO growth reference from 5 to 19 years to develop new curves which are closely aligned with the recommended adult cutoffs for overweight (BMI of 25) and obesity (BMI of 30) at 19 years.[4] The IOTF reference, used for children and adolescents aged 2–18 years, was developed from a database from six countries (Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the USA). BMI values of 25 and 30 at 18 years of age for boys and girls were tracked back to define BMI values for overweight and obesity at younger ages.[5] The IOTF recently updated the international child cutoffs and suggested unofficial Asian cutoffs of 23 and 27 (”Asian” IOTF).[6] Although the WHO and IOTF growth references are considered to be international reference standards, they often lead to differential prevalence estimates for overweight and obesity among children and adolescents.[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17] The Indian Academy of Pediatrics (IAP) Growth Charts Committee has constructed revised IAP growth references for 5–18-year-old Indian children based on data from fourteen cities across India.[18] The present study was conducted with the objective of comparing these three reference standards to check concordance among them.

 Methods



Ethics

The study was approved by the institutional ethics committee and written and informed consent was taken from the parents and assent from children over 7 years of age.

Design

This was a health center-based cross-sectional study conducted in an urban block of District Srinagar – the summer capital of Jammu and Kashmir.

Selection criteria

Children between 5 and 18 years of age attending the health center as patients or accompanying their parents/relatives/friends between April and July 2015 were recruited for the present study. Severely ill children and those with illness duration of >3 days were excluded from the study. Furthermore, children were excluded from the study if the date of birth was not known or if the child/parent was not certain about the date.

Study procedure

The date of birth of the child was recorded and age was measured in completed months and later rounded off to the nearest 6 months interval. Thus, a child aged 11 years and 4 months was considered 11.5 years old and a child aged 11 years and 2 months was considered 11 years old. Weight of the children was measured with light clothing and without shoes using a digital weight scale (Alpha Medicare and Devices Private Limited, Model BS-701) and recorded to the nearest 0.1 kg. Height was measured without shoes using a portable stadiometer (Galaxy Scientific, India) and recorded to the nearest 0.1 cm.

Classification of children and use of the reference standards

A child was classified according to his/her weight status into either of three nonoverlapping categories: (1) obese, (2) overweight, and (3) nonobese nonoverweight –using three growth references based on age- and gender-specific BMI cutoff points. The WHO cutoff points of +1 standard deviation (SD) and +2 SD was used for classification of childhood and adolescent overweight and obesity, respectively.[4] As per the revised IOTF reference curves, BMI corresponding to 23 and 27 at 18 years is recognized as the unofficial Asian cut-off for determining overweight and obesity, respectively.[6] We used these “Asian” cutoffs to define the weight status of a child as per the IOTF reference curve. The adult equivalent of 23 and 27 cutoffs presented in the new IAP 2015 BMI charts [18] was used to define overweight and obesity, respectively, as per the new IAP reference curve.

Statistical analysis

Continuous variables were summarized as mean ± SD. Independent samples t-test was used to compare two independent means. One-way ANOVA was used to compare >2 means. The classification of the study population using new IAP reference was compared to the IOTF and WHO references for each age and sex groups using McNemar-Bowker test. Agreement between new IAP versus WHO and IOTF was analyzed using weighted kappa statistic. Landis and Koch guidelines were used to evaluate kappa (kappa >0.75 - excellent agreement, kappa 0.40–0.75 - good agreement, kappa <0.40 – marginal agreement).[19] Analysis was performed using SPSS 20.0 (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. IBM Corp., Armonk, NY, USA). Weighted kappa (κ) and their 95% confidence interval (CI) were calculated using an online calculator.[20] The value of P Demographics

A total of 362 school-age children and adolescents visited the health center during the study. Of these 16/362 (4.4%) were severely ill or had an illness of >3 days duration. In another 43/362 (11.9%), the date of birth was not accurately known and both these groups of children were excluded from the study. The mean age of the study population was 10.51 ± 3.011 years and the mean BMI was 16.179 ± 3.4033 kg/m 2. Male: female ratio was 1.03 and there were no between group differences in BMI [Table 1].{Table 1}

Comparison of the three growth references revealed that the new IAP cutoffs for overweight and obesity are closer to the “Asian” IOTF cutoffs as compared to the WHO reference for older age groups [Figure 1] and [Figure 2].{Figure 1}{Figure 2}

The overall prevalence of overweight and obesity was similar when measured using new IAP and “Asian” IOTF references (6.6% and 5.0%, respectively, P > 0.999) but was lower when measured using the WHO reference (4.0% and 4.3% for overweight and obesity, respectively, P = 0.002). There was no significant difference in the pattern of BMI status using the new IAP reference and the “Asian” IOTF reference across all age and gender groups [all P > 0.05, [Table 2]. However, significantly different figures were obtained with the WHO references (P = 0.002), especially among males (P = 0.030) and >12–18 years age group (P = 0.030) [Table 2]. There was “excellent agreement” between the new IAP and the “Asian” IOTF references (weighted κ = 0.9558, 95% CI 0.9134–0.9982) which was higher than the agreement between new IAP and WHO references (weighted κ = 0.8517, 95% CI 0.7665–0.9369). This was true across all age and gender groups [Table 3].{Table 2}{Table 3}

 Discussion



The study findings indicated that the prevalence of overweight and obesity are significantly lower when WHO cutoffs are used as compared to the new IAP cutoffs and the “Asian” IOTF cutoffs. An interesting observation was the excellent agreement between new IAP and the “Asian” IOTF references with very high kappa value (κ = 0.9558, 95% CI 0.9134–0.9982).

We compared the new reference curves developed by IAP to the “Asian” IOTF reference curve for the Asian population. There is no known previous attempt at comparing an Indian reference curve with the IOTF cutoff for Asian population in the literature. Researchers have compared an Indian reference with the WHO [21] and IOTF reference.[8] Investigators have compared different international sex-specific BMI for age references revealing differences in prevalence estimates obtained using different criteria.[7],[10],[11],[14],[15] Comparison studies of international versus national sex-specific BMI for age references have been conducted in Brazil,[9] Iran,[12],[13] and France.[16] Most of these studies have compared prevalence estimates of overweight and obesity and have used kappa statistics to evaluate agreement between different reference standards. We have based the present study on more or less similar methodology. One of the limitations of the present study is its use of a health center based sample rather than population-based sample. The prevalence estimates in our study cannot reflect the population parameters due to the lack of external validity. This, however, was not the objective of the study. We believe that the choice of the sample in our study will not affect the comparison of different growth references, the primary objective of this study.

As can be interpreted from [Figure 1], between 7 and 9 years of age the new IAP overweight cutoffs almost overlap the “Asian” IOTF cutoffs. The difference in the cutoffs for overweight and obesity as per the new IAP and the WHO references becomes larger toward the higher age groups of >12 years. Thus, the prevalence estimates obtained using the WHO reference will be much lower in older children when compared to new IAP reference curves.

The prevalence of overweight and obesity in the present study was slightly higher among boys when compared to girls, a finding consistent with other studies from India [8],[22],[23],[24] and abroad.[7],[9],[10],[17] Gender-specific analysis of the data revealed that in both gender groups there was no statistically significant difference in the prevalence of obesity and overweight when defined using the new IAP reference versus the “Asian” IOTF reference. However, when overweight and obesity were defined using the WHO reference the prevalence estimates dropped significantly for boys (P = 0.030) but less so in case of girls (P = 0.083).

Age-specific analysis of the data revealed that the prevalence estimates of overweight and obesity obtained using the new IAP and “Asian” IOTF references were similar across all age groups. There was no statistically significant difference in the weight status as defined using new IAP versus WHO references for younger age groups (5–12 years). However, for older age groups (>12–18 years), the WHO reference produced significantly lower estimates of overweight and obesity prevalence in the study population (P = 0.030). This difference was expected given the fact that the WHO cutoff points are higher than the new IAP cutoff points in older children [Figure 1] and [Figure 2]. There was an excellent agreement between weight status obtained using new IAP and “Asian” IOTF reference which was consistent throughout all age and gender groups. The agreement was slightly lower for >9–12 years age group. Kappa values were slightly lower when new IAP reference estimates were compared with those obtained using the WHO estimates, especially in older children. Nevertheless, given the differences in the prevalence estimates obtained using the three reference systems analyzed in this study, researchers should provide precise information about the reference system they use.

 Conclusion



When measuring overweight and obesity among 5-18-year-old children, researchers should mention the growth reference used for such measurements. The 'Asian IOTF' growth reference is more suitable for use in the Indian context as compared to the WHO growth reference.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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