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Indian Pediatr 2014;51:
544-549 |
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Prevalence of Overweight and Obesity Among
School Children and Adolescents in Chennai
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Sonya Jagadesan, Ranjani Harish, Priya Miranda, Ranjit Unnikrishnan,
Ranjit Mohan Anjana and Viswanathan Mohan
From Madras Diabetes Research Foundation and Dr Mohan’s Diabetes
Specialties Centre, Chennai, India.
Correspondence to: Dr V Mohan, Director and Chief of Diabetes
Research, Madras Diabetes Research Foundation and Dr Mohan’s Diabetes
Specialities Centre, IDF Centre for Education, 4, Conran Smith Road,
Gopalapuram, Chennai 600 086, India. Email:
[email protected]
Received: July 11, 2013;
Initial review: September 10, 2013;
Accepted: April 01, 2014.
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Objectives: To determine the prevalence of overweight and obesity
among children and adolescents in Chennai, India, using national and
international age- and sex- specific body mass index (BMI) cut-off
points.
Methods: The Obesity Reduction and
Awareness and Screening of Non communicable diseases
through Group Education in Children and Adolescents
(ORANGE) project is a cross-sectional study carried out on 18,955
children (age 6-11 years) and adolescents (age 12-17 years) across 51
schools (31 private and 20 government) of Chennai. Overweight and
obesity was classified by the International Obesity Task Force (IOTF
2000) and Khadilkar’s criteria (2012), and Hypertension by the IDF
criteria (in children ³10
years and adolescents).
Results: The prevalence of overweight/obesity was
significantly higher in private compared to government schools both by
the IOTF criteria [private schools: 21.4%, government schools: 3.6%,
(OR: 7.4, 95% CI:6.3-8.6; P<0.001) and by Khadilkar criteria
(private school: 26.4%, government schools: 4.6% OR: 6.9, 95%
CI:6.2-7.8; P<0.001). Overweight/obesity was higher among girls
(IOTF: 18%, Khadilkar: 21.3%) compared to boys (IOTF: 16.2%, Khadilkar:
20.7%) and higher among adolescents (IOTF: 18.1%, Khadilkar: 21.2%)
compared to children (IOTF: 15.5%, Khadilkar: 20.7%). Prevalence of
hypertension was 20.4% among obese/overweight and 5.2% among non-obese
(OR 4.7, 95%CI: 4.2-5.3, P<0.001).
Conclusion: The prevalence of overweight and
obesity is high among private schools in Chennai, and hypertension is
also common.
Keywords: Adolescents, Body mass index, Hypertension,
Nutritional status.
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Obesity has emerged as one of the global health
problems with 200 million school-aged children world-wide categorized as
being overweight/obese, of which 40-50 million are obese [1]. The
factors attributing to increasing childhood obesity are increased intake
of high-calorie foods that are low in vitamins, minerals and
micronutrients coupled with decreased physical activity [2]. Various
studies done in India from 2002-2012 indicate a rising trend in the
prevalence of overweight and obesity in children and adolescents [3-11].
This may have major implications towards increasing prevalence of
non-communicable disease (NCD) like diabetes, hypertension and
cardiovascular disease in early adulthood [11,12].
Data from India related to obesity rates in children
and adolescents comparing both national and inter-national cut-offs are
scarce. We present the age- and sex- specific prevalence of overweight
and obesity among children and adolescents in Chennai using the
International Obesity Task Force (IOTF) guidelines which corresponds to
an adult-equivalent body mass index (BMI) of 25 kg/m 2
and 30 kg/m2 [13], and
Khadilkar’s Asian Indian guidelines for children and adolescents [14];
which corresponds to an adult- equivalent BMI of 23 kg/m2
and 28 kg/m2,
respectively.
Methods
The Obesity Reduction and Awareness of
Non-communicable disease through Group Education (ORANGE) is a large
three-year population-based cross-sectional study on children and
adolescents (aged 6-17 y) of Chennai city, in Southern India. The study
consists of two components (methodology published earlier) namely; the
Colony (community) component and the School component [15]. This paper
deals only with the school component.
Permission was obtained from the Chief Education
Officer, Government of Tamil Nadu, school management of every school and
the Institutional Ethics Committee of the Madras Diabetes Research
Foundation to conduct the study. Informed written consent was obtained
from one of the child’s parents and in addition assent was obtained from
the child before conducting the study.
Twenty thousand children and adolescents aged between
6-17 yrs were screened. The sample size was calculated based on an
estimated prevalence of obesity of 10%, with 80% power, 95% confidence,
and an estimated 3% margin of error to obtain an age- and
gender-specific representative sample of children. Height was measured
in centimeters (cm) using a stadiometer. Weight was measured in
kilograms (Kg) using a standardized weighing machine. Body mass index
(BMI) was calculated using the formula weight (Kg) divided by height in
square meters (m 2). Waist
circumference was measured in centimeters using a non-stretchable fiber
measuring tape. Blood pressure was measured in the left arm to the
nearest 1 mmHg using an electronic machine (Omron Corporation Tokyo,
Japan), with the participant seated in a relaxed position. The
prevalence of overweight and obesity were determined based on the IOTF
criteria [13] and the Khadilkar’s criteria for children and adolescents
[14].
Sampling method: Out of the 1384
government and private schools, listed under the Directorate of
Education, Chennai, Tamil Nadu, 51 schools were selected by systematic
sampling method with a random start. The ratio of government to private
schools was maintained at 2:3 in keeping with the distribution of the
schools in Chennai city. In each school, all students from two to four
randomly selected standards (classes or grades) were screened till the
sample size of 20,000 children and adolescents was reached.
The overall response rate was 95.3% (n=19059).
The 941 non-responders included 641 individuals who did not submit the
written consent form or those who did not give assent for the study, 200
absentees, and 100 participants excluded during data cleaning due to
extraneous values. A further 104 were excluded as they did not meet the
age criteria (<18 years); data of 18955 participants were included in
the final analysis.
For the purpose of this study, participants aged 6-11
years were classified as children and those aged 12-17 years as
adolescents. Participants from government schools were categorized as
belonging to the lower socio-economic group, and those from private
schools as higher socio-economic group.
Statistical analysis: Comparison of continuous
variables was by One-way ANOVA and proportions by the Chi-squared test.
Logistic regression analysis was carried out to examine the relationship
between socio-economic status, gender and age with overweight/obesity.
Analyses were done using Windows based SPSS Statistical Package (version
18.0; SPSS, Chicago,IL).
Results
A total of 18955 children and adolescents (1799
children and 2904 adolescents from 20 government schools, and 6226
children and 8026 adolescents from 31 private schools) participated in
the study. Table I gives the general characteristics of
the participants. The school participants from private schools were
significantly taller and had higher BMI, waist circumference and
systolic and diastolic blood pressure compared to the government school
participants.
TABLE I General Characteristics of the Participants
|
Variables |
Children |
Adolescents |
| |
Boys (n=4478) |
Girls (n=3547) |
Boys (n=4478) |
Girls (n=3547) |
|
Government
|
Private
|
Government |
Private
|
Government
|
Private
|
Government
|
Private
|
|
schools |
schools |
schools |
schools |
schools |
schools |
schools |
schools |
|
(n = 976) |
(n = 3502) |
(n = 823) |
(n = 2724) |
(n = 2147) |
(n = 4040) |
(n = 757) |
(n = 3986) |
|
Age (y) |
9.1 (1.8) |
9.1 (1.6)
|
8.8 (1.7) |
9.2 (1.7)‡ |
14.1 (1.6) |
14.0 (1.5)† |
13.8 (1.6) |
13.9 (1.5)† |
|
Height (cms) |
125.7 (11.6) |
133.7 (11.5)‡ |
123.6 (11.4) |
133.9 (12.7)‡ |
152.1 (12) |
160.9 (11.2)‡ |
147.2 (8) |
155.4 (6.8)‡ |
|
Weight (kg) |
23.2 (6.6) |
30.9 (9.9)‡ |
22.4 (6.3) |
30.9 (10.3)‡ |
39.1 (10.8) |
51.6 (14.3)‡ |
38.6 (9) |
49.8 (11.8)‡ |
|
BMI (kg/m2) |
14.4 (1.8) |
16.9 (3.3)‡ |
14.4 (1.9) |
16.8 (3.3)‡ |
16.6 (2.8) |
19.7 (4)‡ |
17.6 (3.2) |
20.5 (4.2)‡ |
|
WC (cms) |
52.7 (6.1) |
60.1 (9.9)‡ |
52.3 (5.9) |
57.8 (8.5)‡ |
62.4 (8) |
71.8 (11.8)‡ |
61.4 (7.6) |
67.9 (9.3)‡ |
|
Systolic BP (mmHg) |
100 (11) |
105 (11)‡ |
99 (11) |
104 (11) |
108 (12) |
116 (13)‡ |
107 (11) |
112 (12)‡ |
|
Diastolic BP (mmHg) |
62 (9) |
63 (10)‡ |
62 (9) |
63 (9)* |
64 (9) |
67 (9)‡ |
66 (8) |
68 (9)‡ |
|
Z-score HFA |
–0.48 (0.9) |
0.16 (0.9) |
–0.65 (0.9) |
0.17 (1) |
–0.40 (1.1) |
0.43 (1) |
–0.86 (0.8) |
–0.09 (0.6) |
|
Z-score WFA
|
–0.59 (0.7) |
0.18 (0.9) |
–0.67 (0.6) |
0.18 (1) |
–0.63 (0.8) |
0.29 (1) |
–0.67 (0.7) |
0.16 (0.9) |
|
Z-score BMI |
–0.59 (0.6) |
0.18 (1) |
–0.59 (0.6) |
0.16 (1) |
–0.64 (0.7) |
0.11 (0.9) |
–0.40 (0.8) |
0.31 (1) |
|
Values are expressed in Mean (SD), †P<0.01,
‡ P<0.001;WC: Waist curcumference; BP: Blood pressure;
HFA: Height for age; WFA: Weight for age. |
Table II shows the prevalence of overweight
and obesity in children and adolescents. Web Table I shows
the age-wise prevalence (6-17 years) of overweight/obesity in children
and adolescents in Chennai using both the criteria IOTF and Khadilkar’s
criteria. The pre-valence of overweight/obesity was significantly higher
in private schools compared to government schools at all age points,
both among boys and girls.
TABLE II School- and Gender-based Prevalence of Overweight and Obesity in Children and Adolescents
|
Criteria used |
Children |
Adolescents |
|
Government schools |
Private schools
|
Government schools |
Private schools |
|
IOTF [13] N (%) |
|
Boys (N) |
976 |
3502 |
2147 |
4040 |
|
BMI ≥25-29.99 |
16 (1.6) |
568 (16.2) |
77 (3.6) |
725 (17.9) |
|
BMI ≥30 |
3 (0.3) |
148 (4.2) |
9 (0.4) |
185 (4.6)
|
|
Overall |
19 (1.9) |
716 (20.4) |
86 (4.0) |
910 (22.5)
|
|
Girls (N) |
823 |
2724 |
757 |
3986 |
|
BMI ≥25-29.99 |
21 (2.6) |
374 (13.7) |
31 (4.1) |
765 (19.2)
|
|
BMI ≥30 |
3 (0.4) |
107 (3.9) |
8 (1.1) |
182 (4.6)
|
|
Overall |
24 (2.9) |
481 (17.7) |
39 (5.2) |
947 (23.8)
|
|
Khadilkar [14] N (%) |
|
Boys (N) |
976 |
3502 |
2147 |
4040 |
|
BMI ≥23-27.99 |
35 (3.6) |
811 (23.2) |
133 (6.2) |
969 (24.0)
|
|
BMI ≥28 |
8 (0.8) |
407 (11.6) |
33 (1.5) |
439 (10.9)
|
|
Overall |
43 (4.4) |
1218 (34.8) |
166 (7.7) |
1408 (34.9)
|
|
Girls (N) |
823 |
2724 |
757 |
3986 |
|
BMI ≥23-27.99 |
47 (5.7) |
631 (23.2) |
74 (9.8) |
1076 (27.0)
|
|
BMI ≥28 |
9 (1.1) |
313 (11.5) |
22 (2.9) |
569 (14.3)
|
|
Overall |
56 (6.8) |
944 (34.7) |
96 (12.7) |
1645 (41.3) |
|
Values are expressed in n (%); P<0.001 for all measures
between government and private schools; IOTF: International
Obesity Task Force Criteria [13]. |
Regression analysis showed that adolescents had 1.21
times greater odds of being overweight/obese by the IOTF criteria and
1.11 times by the Khadilkar’s criteria than children. Private school
participants had 7.4 times greater odds of being overweight/obese by the
IOTF criteria and 6.94 times by the Khadilkar’s criteria compared to
government school participants. Girls had 1.13 times greater odds of
being overweight/obese by the IOTF criteria and 1.36 times by the
Khadilkar’s criteria, compared to boys.
Table III presents the blood pressure profile
of the study group shows a steady increase in both systolic and
diastolic blood pressure with age. Hypertension diagnosed by IDF
criteria [16], for children ³10
years of age and adolescents was seen in 1185 (8%) participants. The
prevalence of hypertension among overweight/obese children and
adolescents was 20.4% compared to 5.2% among their non-obese
counterparts (OR: 4.7, 95% CI: 4.2-5.3, P<0.001)
TABLE III Blood Pressure Profile of the Study Groups
| |
|
Boys (N=10665) |
|
Girls (N=8290) |
|
Age (y) |
No. |
Systolic BP (mmHg) |
Diastolic BP (mmHg) |
No. |
Systolic BP (mmHg) |
Diastolic BP (mmHg) |
|
6 |
429 |
99 (10) |
60 (11) |
360 |
98 (12) |
60 (10) |
|
7 |
472 |
100 (11) |
60 (10) |
420 |
98 (11) |
60 (11) |
|
8 |
652 |
100 (11) |
60 (9) |
515 |
101 (11) |
61 ( 9) |
|
9 |
724 |
105 (11) |
63 (9) |
540 |
103 (11) |
63 (9) |
|
10 |
976 |
105 (10) |
64 (9) |
704 |
105 (11) |
64 (8) |
|
11 |
1225 |
107 (11) |
64 (10) |
1008 |
108 (11) |
65 (9) |
|
12 |
1354 |
108 (12) |
65 (9) |
1086 |
110 (12) |
66 (9) |
|
13 |
1334 |
110 (12) |
65 (10) |
1011 |
111 (11) |
67 (9) |
|
14 |
1141 |
113 (12) |
65 (9) |
917 |
112 (11) |
67 (9) |
|
15 |
1122 |
117 (14) |
66 (9) |
919 |
112 (12) |
68 (9) |
|
16 |
802 |
118 (14) |
67 (10) |
548 |
112 (11) |
69 (9) |
|
17 |
434 |
120 (12) |
68 ( 9) |
262 |
113 (12) |
70 (9) |
|
Values are expressed in Mean (SD). |
Discussion
This study showed that the overall prevalence of
obesity is high in urban Chennai. This was predominantly dictated by the
high prevalence of obesity in private schools as compared to government
schools. The prevalence of obesity was higher in girls than boys, in
adolescents than children, in private schools than government schools
and higher on using the Khadilkar’s criteria [14], compared to the IOTF
criteria [13].
Most of the earlier studies done in children and
adolescents in India have reported prevalence based on international
cut-off points [3-11], with a meta-analysis estimating the prevalence of
overweight as 12.6% and obesity as 3.4% [17]. Another multicentric study
reported an overall prevalence of overweight/obesity as 18.2% [10]. Our
study adds to the literature by reporting on the prevalence estimates
using both national and international cut points.
A strength of this study is that it is one of the
largest studies done on overweight/obesity in a wide age group of school
children (6-17 years) in a representative sample of Chennai, an urban
area of Southern India. Two studies with comparable sample size were
carried out in Delhi [7,8]. The findings of these studies and our study
show a markedly higher prevalence of overweight/obesity among children
attending private schools in comparison to those attending government
schools. The combined influence of socioeconomic status, lifestyle and
chrono-logical age with a high prevalence of obesity among adolescents
as seen in our study has also been reported earlier [4,18]. However,
even among government schools, the prevalence of overweight/obesity is
significant. This new trend can be attributed to increasing
accessibility and affordability of both junk foods and modes of
motorized transportation resulting in an increased consumption of
energy-dense foods coupled with decreased physical activity in the lower
income group [19].
Our study also shows a higher prevalence rates of
overweight/obesity among girls, as did a previous study done in Chennai
[20]. The influence of gender and adolescence on obesity can be
attributed to hormonal changes at puberty and the development of
secondary sexual characteristics resulting in fat accumulation and
redistribution [21]. Moreover, we had shown earlier, that only 25% of
the girls played outdoors for ³1
hour/day compared to 43% of the boys [22]. Earlier studies showed that
increase in adiposity lead to a higher risk of developing elevated
systolic and diastolic blood pressures and hypertension in children and
adolescents [11,23]. Our study also shows that overweight/obese children
have a 5-fold higher risk of having hypertension than non-obese
children.
The limitation of our study is that it is restricted
to one large metropolitan city. The findings may not be representative
of the whole country or even of the whole State of Tamil Nadu. Only a
truly representative national study, involving both urban and rural
popu-lations, can provide the true picture on the nationwide prevalence
of overweight/obesity.
The higher prevalence of obesity among children and
adolescents attending private schools and among adolescents in general,
suggests a need for targeted intervention, as previously stressed [20].
Obese adolescents have a 70%-80% chance of developing adult obesity [24,
25]. Thus, inculcating and reinforcing both health eating habits
and lifestyle needs to be the norm. The Government of India’s National
Program on Prevention and Control of Diabetes, Cardiovascular Disease,
and Stroke has a school component which needs to be strengthened. There
is also an urgent need to increase awareness via education and
motivation of all stakeholders. This will go a long way in preventing
childhood obesity and thus ultimately stemming the rising tide of
non-communicable diseases such as diabetes and cardio vascular disease
in India.
Acknowledgments: Directorate of Education,
Government of Tamil Nadu, for permission to conduct the study in
Government schools. Management and teachers of the various participating
schools for their co-operation and support. The staff of Translational
Research Department of Madras Diabetes Research Foundation for help in
the conduct of the study.
Contributors: VM: conceived, supervised the study
and revised all drafts of the manuscript; SJ: carried out the study and
wrote the first draft of the article and the study is part of her
ongoing PhD work. RH; supervised and coordinated the study and revised
the manuscript; PM: carried out the statistical analysis and gave
valuable inputs for the article; RU and RMA; gave valuable comments and
revised several drafts of the manuscript.
Funding: Support from an investigator-initiated
study program of Lifescan, Inc., a Johnson & Johnson Company.
Competing interests: None stated.
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What is Already Known?
•
Most of the earlier studies done
in India have given their overweight/obesity prevalence
estimates for children and adolescents based on only
international cut points.
What This Study Adds?
•
The study reports on the prevalence of obesity using the
IOTF (International) and Khadilkar’s (National) cut-points, and
also reports the prevalence of hypertension.
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