Amudhadevi.S.1,SampathKumarD.2
1Dr.AmudhadeviS.,Assistant
Professor, 2Dr. Sampath Kumar D, Associate Professor, Department of
Pediatrics,Govt. Mohan Kumaramangalam Medical College, Salem, Tamilnadu, India
Corresponding Author: Dr.SampathKumar
D.,Associate Professor, Department of Pediatrics, Govt. Mohan Kumaramangalam
Medical College, Salem, Tamilnadu, India, Email: drsampathkumarped@gmail.com
Abstract
Introduction:Childhood obesity has become a single marker for
children at risk for development of various non-communicable diseases later in
life. This study is conducted to estimate the prevalence of obesity and the
risk factors associated with it and to evaluate Waist Height Ratio(WHtR)as a
screening tool to identify obesity in children.Materials and Methods:Across
sectional study of children between 10 and 15 years of age from upper
socioeconomic class from 2 urban schools.Results:
The prevalence of obesity is 11.7% and prevalence of asymptomatic hypertension
is 12%. The Waist height ratio is more than 0.5 in 21.2%. About 50.5% of obese and 40.5% of overweight
children had a WtHR of >0.5. Waist Height Ratio correlated
significantly with all 5 risk factors taken for the study. Conclusion: The prevalence of obesity in children between 10 to 15
years of age in this study is 11.7%. The Waist Height Ratio correlated
significantly with the risk factors. Larger studies specific to Indian children
are needed to make a clear cutoff value for WHtR to improve the sensitivity of
screening.
Key words: Obesity, Hypertension, BMI, Waist Height Ratio.
Author Corrected: 28th July 2018 Accepted for Publication: 31st July 2018
Introduction
World Health Organization(WHO)
describes global obesity as an epidemic affecting at least 300 million people,
with raise in 3fold since 1980[1]. In 1998, WHO declared obesity as a global
epidemic in view of increasing incidence of obesity and its co-morbidities [1].
In 2000, the world-wide number of obese people exceeded the number of
underweight people[1].
Childhood obesity has
become a single marker for children at risk for development of various
non-communicable diseases later in life. The co-morbidities of obesity include
coronary heart disease, hypertension (HTN), dyslipidemia, stroke, cancers, NIDDM
(NonInsulin Dependent Diabetes Mellitus), gallbladder disease, osteoarthritis,
gout and sleep apnea. Besides, the obese children go through social bias and
discrimination making them reluctant to seek medical assistance.
There are several risk
factors like sedentary life style, high caloric dense diets, behavior changes
because of increased urbanization and the regression of traditional life style
patterns. Genetic and familial factors also contribute to obesity [2]. The factors
associated with idiopathic obesity are numerous – age, sex, race, ethnicity,
screen time, energy imbalance, junk foods, sleep hours, etc. The causes for
endogenous obesity are also numerous – endocrine, drug intake, tumors, etc. So
far 600 genes have been identified to be associated with obesity.Childhood
obesity is defined as BMI (Body Mass Index) of more than 95th percentile for
age and sex[3].Childhood overweight is defined as BMI of more than 85th
percentile for age and sex[3].
BMI is most commonly used
to assess weight, and is a dependable marker for adiposity[4]. BMI correlates
with body fat as determined by both skin fold thickness measurement and by
densitometry. Thus, it is a reasonable criterion for determining obesity in
children and adolescents[5].
Various methods are
available to assess obesity like BMI, Waist Circumference, Waist Hip Ratio,
Waist Height Ratio, Skin fold thickness, Dual energy X-ray Absorptiometry, etc.
The aim of this study is to estimate the prevalence of obesity among school
going children between 10 to 15 years, to assess the risk factors associated
with them and to evaluate the Waist Height Ratio (WHtR) as a screening tool for
obesity.
Materials and Methods
A cross sectional study
was conducted in 2 schools after taking clearance from ethical committee. The
inclusion criteria are to evaluate all Children between the age group of 10 -15
years belonging to upper socio-economic status as per Modified KuppusamyClassification.
Children below 10 years and above 15 years and children diagnosed to be obese
due to endogenous causes based on past medical history and clinical examination
was excluded. The height was measured using sliding Stadiometer with an
accuracy of 0. 1mm.Weight was recorded using electronic weighing scale calibrated
to 0.05kg accuracy. Body Mass Index (BMI) was calculated from height and weight.
Children were categorized as Normal, Overweight, obese and underweight based on
BMI as per National Center for Health Statistics (NCHS) guidelines with respect
to their age and sex.Resting Blood Pressure (BP) was determined using mercury
manometer with appropriately sized cuffs. Hypertension is defined as average
systolic or diastolic BP ≥ 95th percentile for age, sex and height,
measured on 3 separate occasions[6].Elevated BP was confirmed on repeated
visits before characterizing an individual as having HTN, because of the
accommodation effect (anxiety induced changes in BP). A stretch resistant tape
was used to measure waist and hip circumference. Waist circumference was taken at midpoint
between the crest of the iliac bone and the sub costal margin in the mid
axillary line. Hip circumference was taken at the largest circumference of the
buttocks. To
analyze the life style factors and dietary habits in obese and non-obese
groups, a pre-tested proforma was designed and explained to each individual
parent and was asked to collect data regarding the child's dietary pattern
including food given in between meals and snacks for a period of 3 days, when
the child was healthy.Later, the mean calorie intake of each child was
calculated and compared with normal calorie requirement of the child for age
and sex and was entered in the proforma as normal, caloric excess or caloric
deficit. Child's physical activity (outdoor activity) and T.V viewing / video
games/ computer games were also recorded in minutes per day for 3 consecutive
days including one Sunday, when the child was healthy.
Results and Analysis
The
results are tabulated in tables 1,2 and 3. There were 1011 children in the
study group.Out
of 1011 children included in the study, 54.2% were male and 45.8% were female
children. In the study group the overall prevalence of overweight and obesity
was 21.5% and 11.7% respectively.There
is no statically significant difference in gender distribution for obesity and
overweight. There is a simple linear progression in caloric intake in normal
weight, overweight and obese children. About 13.2% of normal weight children
65.1% of overweight and obese children had excess caloric intake. Junk food
intake or sweetened beverages of more than 2 servings per week (around 280
kcal) was taken as risk as per AAP guidelines.
Table-1:
Profile of children in study group
|
No |
% |
Age distribution |
||
10 years |
132 |
13.1 |
11 years |
90 |
8.9 |
12 years |
217 |
21.5 |
13 years |
209 |
20.7 |
14 years |
231 |
22.8 |
15 years |
132 |
13.1 |
Sex distribution |
||
Boys |
463 |
45.8 |
Girls |
548 |
54.2 |
BMI distribution |
||
Under Nutrition |
82 |
8.1 |
Normal |
594 |
58.8 |
Over weight |
217 |
21.5 |
Obese |
118 |
11.7 |
Waist height ratio |
||
< 0.5 |
796 |
78.73 |
> 0.5 |
215 |
21.27 |
Blood pressure |
||
Normal |
889 |
87.9 |
Hypertension |
122 |
12.1 |
Waist circumference |
||
< 90th centile |
881 |
87.1 |
> 90th centile |
130 |
12.9 |
Table-2: Profile of children in study group
|
Under nutrition |
Normal |
Overweight |
Obese |
|
Age distribution |
|||||
10 years |
20(24.39%) |
70(11.98%) |
57 (43.1%) |
18(13.6%) |
|
11 years |
14(17.07%) |
88(15.06%) |
16(17.7%) |
10(11.1%) |
|
12 years |
15(18.29%) |
106(18.15%) |
42(19.3%) |
50(23%) |
|
13 years |
12(14.63%) |
125(21.4%) |
49(23.4%) |
27(12.9%) |
|
14 years |
13(15.85%) |
102(17.46%) |
33(14.2%) |
13(5.6%) |
|
15 years |
8(9.75%) |
93(15.92%) |
20(15.1%) |
0 |
|
Gender distribution |
|||||
Male |
66(12%) |
300(55%) |
58(11%) |
66 (12%) |
|
Female |
16(3.5%) |
294(63.4%) |
60(13%) |
16 (3.5%) |
|
Caloric intake |
|||||
Mean caloric intake |
1560Kcal |
1907 Kcal |
2106 Kcal |
2211 Kcal |
P value <0.15 |
Caloric excess |
0 |
89 |
143 |
75 |
<0.05 |
WHtR |
|||||
<0.5 >0.5 |
75(91.46%) 7(8.64%) |
539(90.74%) 55(9.26%) |
129(59.44) 88(40.56) |
53(44.91%) 65(55.09%) |
<0.05 |
In
our study 36.9% of normal weight, 79.3% of overweight and 90.7% of obese
children comes under risk. As per AAP recommendation, physical activity of less
than one hour per day is considered to be a risk factor for obesity. In the
study among risk group of reduced physical activity 57% were in non obese group
and 82% belonged to obese and overweight group taken together. Sleep duration
of less than 6 hours is considered as risk factor for obesity. In our study
64.2% of overweight and obese group had reduced sleep duration as compared to
22.5% of non-obese group. Screen time is the time spent in television viewing,
videogames, social networking sites etc. Screen time of more than 2 hours per
day is considered as risk. In our study 38.8% of obese & overweight
children and 9.65% of non-obese group come under risk group. In our study the
prevalence of asymptomatic hypertension is 12%. Systolic or diastolic BP ≥ 95th
percentile for age, sex and height is taken as hypertension. About 24.9% of
overweight and 50% of obese children had associated hypertension. The incidence
of hypertension correlates significantly with obesity.
Table-3: Correlation with the risk factors and BMI
|
Undernourished |
Normal |
Overweight |
Obese |
P value |
Junk food intake |
|||||
No risk |
74(90.2%) |
375(63%) |
45(20.7%) |
11(9.3%) |
<0.05 |
Risk |
8(9.8%) |
219(36.9%) |
172(79.3%) |
107(90.7%) |
|
Physical activity |
|||||
No risk |
41(50%) |
253(42.6%) |
56(25.8%) |
4(3.4%) |
<0.05 |
Risk |
41(50%) |
341(57.4%) |
161(74.2%) |
114(96.6%) |
|
Sleep duration |
|||||
No risk |
66(80.5%) |
448(75.4%) |
77(35.4%) |
43(36.4%) |
<0.05 |
Risk |
16(19.5%) |
146(24.5%) |
140(64.5%) |
75(63.5%) |
|
Screen time |
|||||
No risk |
72(87.8%) |
539(90.8%) |
136(62.7%) |
78(66.1%) |
<0.05 |
Risk |
10(12.2%) |
55(9.2%) |
81(37.3%) |
40(33.9%) |
|
Hypertension |
|||||
Normal |
82(100%) |
585(98.5%) |
163(75.1%) |
59(50%) |
<0.05 |
Hypertension |
0 |
9(1.5%) |
54(24.9%) |
59(50%) |
|
WHtR |
|||||
<0.5 |
75(91.4%) |
539(90.7%) |
129(59.5%) |
53(44.9%) |
<0.05 |
>0.5 |
7(8.6%) |
55(9.3%) |
88(40.5%) |
65(55.1%) |
Waist
height ratio >0.5 is considered as a risk factor for central obesity.
WHtR<0.5 is taken as no risk. Among 1011 children, 215(21.2%) of the study
population are with WHtR>0.5. About 40.5% of overweight children and 55.5%
of obese children in the study group had WHtR>0.5. WHtR correlates
significantly with obesity. About 34.9% of children with WHtR>0.5 had
hypertension, while hypertension occurs in 6% of children with WHtR>0.5.
About 83.7% of children with WHtR>0.5 had reduced physical activity. Thus
waist height ratio >0.5 correlates with reduced physical activity. Sleep
duration of less than 6hours is considered as risk factor. From our study (129)
60% of children with WHtR>0.5 had reduced sleep duration. According to AAP,
waist circumference > 90th percentile is a significant risk
factor of central obesity. In the study population, 87.1% of children are with
waist circumference <90th percentile, while 12.9% of children
have central obesity >90th percentile.
Discussion
Obesity has become a
pediatric public health problem associated with risk of complications in
childhood and increasing morbidity and mortality in adulthood. The prevalence
of childhood obesity keeps increasing due to changes in eating pattern [7],
sedentary life, increased junk food intake and sweetened beverages, reduced
participation in outdoor sports activities, addiction to television viewing,
video games, social networking sites, etc.Thus, obesity in children has emerged
as an important focus in pediatric research and practice.
The prevalence of obesity
among school children varies from least of 2.5% in Africa to a maximum of 30%
in developed countries like United States.In our country the prevalence of
obesity varies in urban and rural population, also in various socioeconomic
classes[8].This study is conducted in two private urban schools in Salem
district belonging to higher socio-economic class. The prevalence of overweight
and obesity is 21.5% and 11.7% respectively in the present study. The
prevalence of obesity in the other studies varies from 3.56% to 16%. There was
no significant difference in gender distribution. It is comparable to the
prevalence in developed countries like America. This is probably due to the
fact that the sample population is derived from two urban schools in the upper socio-economic
class[9].
The prevalence of
asymptomatic hypertension is 12%, increases progressively with the increase in BMI
[10]. The prevalence of hypertension in other studies was about 4.5%.In our
study 24.9% of overweight and 50% of obese children had associated
hypertension. Thus, in the present study the prevalence of asymptomatic
hypertension is significantly higher correlatin1g with the increasing
prevalence of obesity.
From our study 13.2% of
normal weight children 65.1% of overweight & obese children had excess
caloric intake. Mean caloric excess intake correlated significantly with obesity.
In our study 36.9% of normal weight, 79.3% of overweight and 90.7% of obese
children comes under risk. Increased junk food intake is a risk factor which
correlates significantly with Obesity [11].
In our study,57.4% of
normal weight, 74.2% of overweight and 96.6% of obese children had reduced
physical activity of less than one hour. Correlation between reduced physical
activity and obesity is significant in our study.In a cross sectional study by
Hazzaa Al Hazzaa et al[12], conducted among children of 15 to 19years of age in
Saudi Arabia, reduced physical activity correlates with obesity.
Reduced sleep duration is
seen in 24.5% of normal weight, 64.5% of overweight and 63.6% of obese
children. Correlation with reduced sleep duration of less than six hours and
obesity is significant with a p value <0.05.There was a temporal association
between reduced sleep duration and obesity as per the 13 year prospective study
conducted in US by gregor et al[13].
In our study 38.8% of
obese &overweight children spent screen times of more than two hours while
its 9.65% in non-obese group.A cross sectional study done at New Zealand, by
Irene Braithwaite el al[14], there was a positive correlation of television
viewing and obesity[15][16].
WHtR is also a marker of
central obesity when compared to BMI. Among 1011 children, 215(21.2%) of the
study population had WHtR>0.5. In the present study, WHtR is also a good
indicator of central obesity as 40.5% of overweight children and 55.5% of obese
children had significant risk as WHtR>0.5. Weight height ratio correlates
significantly with obesity with ap value of <0.05. According to a study done
in UKby MaCarthy el al[17], waist height ratio is an important marker for
central obesity.
In our study, 34.9% of
children with WHtR> 0.5 had hypertension, while hypertension occurs in 6% of
children with WHtR<0.5.Based on the
cross sectional study byMichael Khoury et.al[18] abnormal waist height
ratio is related to cardio metabolic risk factors in children.
In our study, 83.7% of
children with WHtR>0.5 had reduced physical activity. Correlation between
WHtR and reduced physical activity is significant with p value < 0.5.Waist height ratio correlated well with sleep
duration in the study. Correlation is significant as 60% of children
with WHtR>0.5 had reduced sleep duration.
ThusWHtR correlates well with
all risk factors. Hence it can be used as a screening tool to identify central
obesity and other co-morbid conditions like hypertension[19].
In
this study only 50.5% of obese and 40.5% of overweight children had a WtHR of
>0.5. In a study by Seeja et al in 2013, it was suggested that a WHtR of
>0.48 can be used to improve the sensitivity in screening obese and
overweight children in India [20].Hence larger studies specific to
Indian children are needed to make a clear cutoff value of WHtR to improve the
sensitivity of screening.
Conclusion
The prevalence of obesity
in the study is 11.7% and prevalence of overweight is 21.5% in the study. The
overall prevalence of asymptomatic Hypertension in the study population was
12%. The prevalence of Hypertension among obese children was 50% as compared to
9.1% in normal weight children. The obese children had a statically significant
correlation with risk factors of Mean Caloric Intake Excess, Junk food Intake,
Reduced Physical Activity, Increased Screen Time and Reduced Sleep duration.
There is a growing
consensus by the researchers worldwide to accept the Waist Height Ratio as the
important screening tool for Central Obesity in children. In this study we
analyzed the usefulness of Waist Height Ratio as a screening tool for obesity
and found it to be significantly correlating with BMI. Further Waist Height
Ratio also significantly correlates with risk factors like Mean Caloric Intake
Excess, Junk food Intake, Reduced Physical Activity, Increased Screen Time and
Reduced Sleep duration. Larger studies specific to Indian children are needed
to make a clear cutoff value for WHtR to improve the sensitivity of screening.The
policy makers and parents should keep in mind the risk factors associated with
obesity and formulate a healthy life style for the younger generation to
eliminate these risk factors. A public health campaign of ‘keep the waist less than half of your height’ will make significant
impact in the mindset of people.
Limitations of the study: This study is conducted
in two urban schools in which may not be representative of entire community.
Funding: None
Conflict of Interest: None
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