Prevalence of obesity in school
children aged 11-15 years in western district of Tamil Nadu
Suganthi V.1, Arunthathi
A.2, Nayana T.3
1Dr. Suganthi.V, Professor and HOD, Department of Pediatrics,
Coimbatore Medical College Hospital, Coimbatore, 2Dr. Arunthathi. A,
Senior Resident, ESI Medical College, Coimbatore, 3Dr. Nayana. T, Junior
Resident, Coimbatore Medical College Hospital, Coimbatore, Tamil Nadu,
India
Corresponding Author:
Dr. A. Arunthathi, Senior Resident, ESI Medical College, Coimbatore, 752,
Cross cut road, Andavar Complex, Gandhipuram, Coimbatore-12. E mail id:
a.arunthathi@gmail.com
Abstract
Introduction:
Obesity in children and adolescents is an important public health
problem in India. This study was done to estimate the prevalence of
obesity in 11-15 years urban school children using Body mass index.
(BMI), waist circumference (wc), waist height ratio (WHtR) and to
determine the screen viewing time – arisk factor for obesity.
Methods:
This was a descriptive cross-sectional study. It was conducted over 12
months in the year 2014 in 11- 15 years urban school children in
Coimbatore district. About 859 children were selected for this study. A
proforma was used to collect the details such as age, gender, type of
school, screen viewing time. Weight, height, waist circumference of
these children was measured and prevalence of obesity was estimated
based on the 3 indices- BMI, WC, WHtR. The data were analyzed with a
statistical software package. Results:
Out of the 859 children, the sample strata was 170 for each age group
from 11-15 years. About 5% were obese by BMI, 18 % by WC, 14% by WHtR.
The prevalence in females was 7% (BMI), 22% (WC), 17% (WHtR) and in
males it was 1%(BMI), 10%(WC), 7%(WHtR). The prevalence of obesity in
private schools was 10%. (BMI), 21%(WC), 16% (WHtR) and in government
schools, it was 3% (BMI), 9% (WC), 7%(WHtR). The prevalence in screen
viewing time less than 2 hours was 3%(BMI), 9%(WC),12%( WHtR), and in
more than 2 hours it was 10% (BMI), 20% (WC), 23% (WHtR). Conclusion: The
prevalence of obesity in high school children according to BMI is 5%.,
WC 18% and WHtR 14%. It is more in females, children studying in
private schools and in those with screen viewing time more than 2 hours.
Keywords:
Childhood obesity, body mass index, waist circumference, waist height
ratio
Manuscript received:
6th December 2017,
Reviewed: 16th December 2017
Author Corrected:
23rd December 2017,
Accepted for Publication: 28th December 2017
Introduction
Childhood obesity is a serious health problem of the 21st century as it
is the precursor of adverse effects occurring in adulthood [1].Obesity
is a subclinical inflammation characterized by the secretion of
cytokines that influence the formation of atherosclerotic plaques and
endothelial dysfunction. This inflammatory process begins in
childhood[2]. The prevalence of obesity in a population is an indicator
of health burden due to non- communicable diseases in developing
countries[3]. There is a great need for studying obesity in India
because there is an increase in type 2 Diabetes mellitus in Indian
adults[4].
In adolescents,central or abdominal fat increases the risk for
metabolic and cardiovascular complications[5]. Indices predictive of
adolescent central obesity include waist circumference(WC), waist to
hip ratio (WHR), waist to height ratio (WHtR).
Only few studies could be traced in literature which estimated the
prevalence of childhood obesity using all the three indices-BMI, WC,
WHtR.Estimated prevalenceof obesity in school children would help in
developing appropriate interventions to reduce obesity among this
population. With this background we designed this
cross–sectional study to estimate the prevalence of obesity
using the 3 screening indices BMI,WC,WHtRamong school children11-15
years of age.
Materials and Methods
Type of study: This was a school based descriptive cross-sectional
study.
Place of study: This was carried out in urban school children in
Coimbatore district, Tamil Nadu for a period of one year. Ethical
clearance was obtained from Institutional ethical committee and consent
was obtained from Chief Educational Officer (Coimbatore Corporation).
Inclusion criteria: Urban school children, of age 11 to 15 years were
included in the study.
Exclusion criteria: Students with major dysmorphology or signs
ofphysical deformity were excluded.
Sample collection: The student was considered obese 1) if he or she was
more than or equal to 27th adult equivalent of IAP BMI chart 2)WC was
more than or equal to 75th percentile of Smoothed and Weighted Age and
Sex Specific Waist Circumference Percentile Values(cm)for Indian
children 3- 16 years of age 3)if he or she was more than or equal to
0.5 as per the Smoothed and Weighted Age and Sex Specific Waist Height
(WHt) ratio percentile values for Indian children3-16years of age.
A proforma was used and details were collected which included age,
gender, type of school, and screen viewing time. Height was measured
using a portablestadiometer, weightwas measured using electronic
weighingscale, and WC using a non stretchable elastic tape according to
WHO standards.
Sample size calculation formula n= t2*p(1-p)/m2, wheren= required
sample size, t= confidence level of 95 %(standard value of 1.96),
p=expected frequency of the factor under study 14.7%, m= margin of
error of 2.5%,n= 1.962*0.147(1-0.147)/0.0252 =770.The sample is
increased by 10 % to account contingencies like non-response and
recording error. The sample size calculated was 850. About 50% of
samples was chosen from Government schools and 50% from private schools.
Under the above-mentioned formula, previous studies and in consultation
with the statistician, the sample size was calculated to be 850 and the
sample strata was calculated to be 170 for each group from 11-15 years.
Sampling method- About 859 subjects from Coimbatore district were
selected for this study. We adopted a multistage stratified random
sampling procedure. Schools were selected basedon the list of schools
in Coimbatore, which was obtained fromthe District Education Office.
Both government and private schools were included, and the ratio was
1:1 in accordance with distribution of schools in Coimbatore. Students
who did not submit the proforma or those who were not cooperative were
considered as non-respondent.
Statistical analysis- A chi square test was used to assess the
difference in categorical variables between groups. A p value of
<0.05 using a two-tailed test was taken as being of significance
for all statistical tests. Alldata wereanalysed with a statistical
software package. (SPSS, version 16.0 for windows).
Results
About 859 children were enrolled.
Table-1: Age and Gender distribution
|
Age
|
Males
|
Females
|
Total
|
|
11
|
68
|
106
|
174
|
|
12
|
75
|
96
|
171
|
|
13
|
85
|
86
|
171
|
|
14
|
50
|
122
|
172
|
|
15
|
61
|
110
|
171
|
|
Total
|
339
|
520
|
859
|
The male and female children were 339 and 520 respectively (Table-1).
Table-2: Prevalence of obesity
|
|
BMI
|
WC
|
WHtR
|
|
Obese
|
n
|
%
|
n
|
%
|
n
|
%
|
|
43
|
5
|
154
|
18
|
120
|
14
|
|
Non -obese
|
816
|
95
|
705
|
82
|
739
|
86
|
n= frequency of children
According to BMI-43 Children (5%), WC-154 Children (18%), WHtR- 120
children (14%) were obese. (Table2).
Table-3: Association of gender with obesity (p<0.05)
|
|
Males339
|
Females520
|
|
n
|
%
|
n
|
%
|
|
BMI
|
3
|
1
|
36
|
7
|
|
WC
|
33
|
10
|
114
|
22
|
|
WHtR
|
23
|
7
|
88
|
17
|
n= frequency of obese children
Out of 859 children, 339 were males and 520 were females. Using all 3
indices, obesity was more common in girls than boys and it was
statistically significant (table-3).
Table-4: Association of type of school withobesity (p<.05)
|
|
Private school– 459
|
Government school-400
|
|
n
|
%
|
n
|
%
|
|
BMI
|
45
|
10
|
12
|
3
|
|
WC
|
96
|
21
|
36
|
9
|
|
WHtR
|
73
|
16
|
28
|
7
|
n=frequency of obese children
Out of 859 enrolled children, 459 were from private schools and 400
from government schools. Obese children were more in private schools
than in government schools and it was statistically
significant(Table-4).
Table-5: Association of screen viewing time with obesity
(p<0.05)
|
|
Less than 2 hours (514)
|
More than 2 hours (345)
|
|
n
|
%
|
n
|
%
|
|
BMI
|
15
|
3
|
34
|
10
|
|
WC
|
46
|
9
|
69
|
20
|
|
WHtR
|
88
|
12
|
79
|
23
|
Among 859 children, 514 had screen viewing time less than 2 hours
and345 had screen viewing more than 2 hours.Obesity was more common in
2nd group and it was statistically significant (Table-5).
Discussion
In our study, 859 children were taken up according to inclusion and
exclusion criteria. Among the study groups, the prevalence of obesity
based on BMI was 5%, WC -18%, WHtR- 4%. Estimates of prevalence of
obesity were studied by Midha T [6] by meta-analysis based on BMI was
3.31%. Nine studies including 92,862 children were identified and
analysed in the meta- analysis. Schroden H [7] did a study to determine
the prevalence of abdominal obesitybased onWC & WHtR in Spanish
children and adolescents aged 6 to 17 years. The prevalence of WHtR
>=0.5 was 14.3%, WC>=90th percentile was 9.6% in
adolescents. In a study by Mustaq MU [8] age and gender specific
smoothed percentiles for WC, WHtR were developed for a sample of 1860
children, aged 5 to 12 years. In that study 12% children had a WC of
=>90th centile, 16.5% children had a WHtR =>0.5 while
11%had both. WC provided a better estimate of visceral adipose tissue
and WHtR was age independent. In the cross-sectional study by Taheri F
[9] conducted on 2458Iranian students, aged 11-18 years, the prevalence
of WC >90thcentile was 16.3%.A systematic review was done by de
Moraes A C [10] on the prevalence of abdominal obesity in adolescents
(10- 19) years old, theprevalence of abdominal obesity varied from 8.7%
to 33.2%. This wide range is partly due to actual population
disturbances and partly due to the cut offpoints used to define
abdominal obesity.
Among 859 children, 339 were males and 520 were females. The prevalence
of obesity based on the 3 indices (BMI,WC,WHtR) were more common in
girls.This was in part due to the sedentary lifestyle. Kumar S [11]
estimated the prevalence of obesity in 1496 students aged 10-
15years.The prevalence based on BMI was more common in girls (8.82%)
than boys(4.1%). The difference was statistically
significant.Bamoshmoosh M [12] estimated central obesity in a sample of
3114 Yemeni children aged 6-19 years. The prevalence based on WC and
WHtR was 1.22 times more common in girls. In Yemen central obesity is
more common in adult women than in men and according to this study,
this difference originates at early adolescence.
Out of 859 enrolled children, 459 were private school and 400 from
government schools. Obese children were more common in private schools
than government schools. The prevalence was more in private schools
than government schools and it was statistically significant. Children
in private school were more affluent.Preetam B Mahajan[13] did a study
on obesity in children between 6-12 years from government and private
schools in Puducherry. Prevalence of obesity according to BMI was 1.82%
in government schools and 2.48% in private schools. In a study done by
Jagadesan S [14] on 18955 children aged 6- 17 years across 51 schools
of Chennai, the prevalence of obesity was significantly higher in
private (21.4%) compared to government schools.
Among 859 children, 514 had screen viewing time less than 2 hours and
345 had more than 2 hours. Obesity was significantly higher in second
group. The American Academy of Pediatrics recommends no more than 2
hours/day of screen viewing time(watching television, videos, playing
video games and using computer for purposes other than school work
[15]. A meta-analysis by Zhang G [16] included 14 cross sectional
studies containing 1,06,169 subjects to evaluate the association
between obesity and television watching. A linear dose response
relationship was found for television watching and obesity and the risk
increased by 13% for each 1 hour/day increment in TV watching. There
are limitations and strengths in this study. A first limitation is the
unequal number of boys and girls in the stratified age groups. Secondly
the pubertal development status was not assessed.
The strengths of our study are - 1. The novelty of comparing the 3
anthropometric indices as screening tools for obesity. 2. The sample
being obtained from both government and private schools.
Conclusion
WC and WHtR are better than BMI in detecting obesity. The prevalence of
obesity is higher among girls, in children studying in private schools
in Coimbatore. Screen viewing time more than 2 hours /day is associated
with a higher risk of obesity. Body Mass Index is the most traditional
anthropometric index used for diagnosing obesity.This study reinforces
the importance of including the WC, WHtR measurements in routine
anthropometric evaluation. National programs should be aimed at
periodic obesity screening of school children and sensitizing about
healthy foods, outdoor activities and screen viewing hazards.
What is already known: BMI is the most common anthropometric index used
for diagnosing obesity.
What this study adds: WC and WHtR are better than BMI in detecting
childhood obesity.
Abbreviations used: BMI – Body Mass Index, WC –
Waist Circumference, WHtR – Waist Height Ratio
Funding:
Nil, Conflict of
interest: None initiated.
Permission from IRB:
Yes
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How to cite this article?
Suganthi V, Arunthathi A, Nayana T. Prevalence of obesity in school
children aged 11-15 years in western district of Tamil Nadu. Int J Pediatr Res. 2017;4(12):727-732.doi:10.
17511/ijpr.2017.12.06.