Prevalence of Obesity is Rising Among Primary School Children in Dhaka City of Bangladesh

BK-Rauniyar, Sharmin-Jahan, Nusrat-Sultana, Mashfiqul-Hasan, M

Atiqur-Rahman, Yasmin-Aktar, M Fariduddin and M A Hasanat*

Bangladesh

*Corresponing author: MA Hasanat, Professor of Endocrinology, Department of Bangladesh, Tel: +880 1711 670735; Email: hasanatdr@yahoo.com addressed accordingly.

as well as blood pressure were considered as influencing factors.

independent predictors for BMI.

stakeholders to initiate appropriate measures to combat this rising prevalence.

Keywords: Childhood obesity; Anthropometric Indices; Waist-height Ratio

Introduction

Childhood obesity poses a major public health challenge in both developed and developing countries by increasing the burden of chronic non-communicable diseases. It has reached epidemic proportions and is the most prevalent chronic condition affecting health of children and adolescents worldwide [1]. Though adult body mass index (BMI) thresholds of 25 and 30 kg/m2 is considered for overweight and obesity respectively, there is little consensus as to the best way to operationalize this definition in children [2]. Children with BMI equal to or exceeding the age-gender-specific 95th percentile are defined obese. Those with BMI equal to or exceeding the 85th but below 95 percentiles are defined overweight and are at risk for obesity related co-morbidities [3].

The World Health Organization (WHO) estimated that the prevalence of children <5 years of age with a BMI more than 2 standard deviation (SD; equivalent to the 98th percentile) increased from 4.2% in 1990 to 6.7% in 2010 and is expected to reach 9.1% in 2020 [4]. These worldwide trends in very young children are dramatic and have raised debate as to whether we can and should diagnose obesity even during infancy [2]. According to the BMI cut-off values specific for Asia-pacific region, almost one fourth of the population of Pakistan is overweight and obese [5]. According to recent Indian data, prevalence of overweight among 14 – 17 year old urban children in 2006-2007 was 29% in private schools and 11.3% in government-funded schools [1].

Obesity has been studied extensively in many developed countries, but in Bangladesh studies and data related to obesity in children and adolescents are relatively scarce. A positive association between obesity with higher socio-economic status, lack of physical activity and urban residence has been reported. These findings are in accordance with studies from other developing countries which identified the similar risk factors [6]. The present study was carried out to explore childhood overweight and obesity in primary school children in Dhaka, the capital city of Bangladesh.

Results

Mean age of the children was 11.3±1.39 (year, M±SD), 256 (50.8%) were boys and 248 (49.2%) were girls. Following categorization on socioeconomic strata, 161 (31.9%) were from low socioeconomic status, 262 (52.0%) were from middle and 81 (16.1%) were from high socioeconomic status (Table 1). Among the children, 12.9% (65/504) were overweight and 10.9% (55/504) were obese (Figure 1). It was observed that, 11.7% and 12.5% of the boys were overweight and obese respectively, frequencies of which were 14.1% and 9.3% in the girls (p<0.001; Figure 2). Abdominal obesity measured as waist circumference in both the boys and girls is shown in Figure 3. (Boys: 73.0% vs. 11.3% vs. 15.6%; Girls: 73.8% vs. 17.3% vs. 8.9%; normal vs. overweight vs. obese; p=0.02). Waist-height ratio (WHtR) was high in 22.6% children (21.5% boys vs. 23.8% girls; p=0.536; Figure 4). About 94% of the children had normal waist hip ratio (WHR) and only 6.2% were obese in this regard (9.4% boys vs. 2.8% girls; p=0.002; Figure 5).

Frequency of obesity was higher in children from high socioeconomic class, whereas frequency of underweight children was more in lower socioeconomic class (high vs. middle vs. low socioeconomic status: obese 22.2% vs. 11.8% vs. 3.7%; overweight 17.3% vs. 13.7% vs. 9.3%; normal BMI 55.5% vs. 63.0% vs. 68.3%; underweight 4.9% vs. 11.5% vs. 18.6%; p<0.001; Table 2). Systolic blood pressure (SBP) was observed to be in hypertensive range in 19.6% children while diastolic blood pressure (DBP) in 29.8%. In obese and overweight children, there was significantly higher frequency of both systolic and diastolic hypertension (Table 3).

BMI positively correlated with age (r=0.241), WHtR (r=0.800), WC (r=0.859), WHR (r=0.233), SBP (r=0.388), DBP (r=0.282) and socioeconomic condition (r=0.286) with level of significance of p<0.001 for all (Table 4).

Sex Boys 256 50.8 Girls 248 49.2

Class IV 207 41.1 V 297 58.9 Socioeconomic Status Low socioeconomic 161 31.9 Middle socioeconomic 262 52 High socioeconomic 81 16.1 Socio-economic status was classified according to the gross monthly income of the family High: > 40000 taka Middle: 15000-39000 taka Low: < 15000 taka

Click to enlarge

Figure 1: Body mass index (BMI) categories of children (n=504). BMI calculated under reference cut-off value by Center for Disease Control (CDC) Under weight : BMI <5th percentile Normal : BMI ≥5th to < 85th percentile Overweight : BMI ≥85th to < 95th percentile Obese : BMI ≥ 95th percentile Variables Frequency Percentage Age (years; mean ± SD) 11.31±1.39

Click to enlarge

Click to enlarge

Click to enlarge

Figure 4: Waist height ratio status of the boys and girls. Waist height ratio: calculated by dividing the waist circumference in cm by height in cm Normal <0.50 Obese ≥0.50 BP status Underweight Normal Overweight Obese total χ2, P Systolic BP Normal 55 (85.9) 226 (70.6) 33 (50.8) 21 (38.2) 335 (66.5) Prehypertension 3 (4.7) 46 (14.4) 16 (24.6) 5 (9.1) 70 (13.4) Hypertension 6 (9.4) 48 (15.0) 10 (24.6) 29 (52.7) 99 (19.6) Total 64 320 65 55 Diastolic BP 36.731 <0.001 Normal 50 (78.1) 196 (61.3) 32 (49.2) 16 (29.1) 294 (58.3) Prehypertension 3 (4.7) 41 (12.8) 6 (9.2) 10 (18.2) 60 (11.9) Hypertension 11 (17.2) 83 (25.9) 27 (41.5) 29 (52.7) 150 (29.8) Total 64 320 65 55 (Within parenthesis are percentages over column total) BP : Blood pressure Normal BP : SBP and DBP < 90th percentile Prehypertension : SBP or DBP ≥ 90th percentile to <95th percentile Hypertension : SBP or DBP ≥95th percentile

Click to enlarge

Discussion

Childhood overweight and obesity has become a serious public health problem because of its strong association with adulthood obesity and the related adverse health consequences. Most likely it results from an interaction of nutritional, psychological, familial and physiological factors. The present study was undertaken to explore childhood overweight and obesity in primary school children in Dhaka city of Bangladesh.

The prevalence of overweight and obese children has been found to be 12.9% and 10.9% respectively by using CDC growth chart of BMI. International literature has portrayed developing countries as having a relatively low prevalence of obesity coexisting with a high prevalence of underweight. Similar observations were reflected by several other studies undertaken in ours and neighboring countries as well [5, 7]. A study conducted by Sultana et al, in 2010 in Dhaka city reported a frequency of overweight and obesity 13.2% and 17.8% respectively among 6 -13 years school going children, while another study by Ferdousi, et al. in 2011 showed frequency of overweight 18.32% among 6-10 years children in urban community of Bangladesh [8, 9].

BMI status was categorized in the context of different socioeconomic groups. As expected the frequency of obese and overweight were higher in high and middle socioeconomic class while the frequency of underweight was more in low and middle socioeconomic class, it was in keeping with other observations as well [10, 11]. This finding is contrary to that in developed countries such as the UK where an association between social deprivation and childhood obesity was strong, especially in the girls. One possible explanation for this difference might be the influence of lifestyle factors such as diet, food consumption patterns, and public services such as health care and transportation and physical activity. Richer people have better access to meat and other energy-dense foods than the poor. On the other hand, middle socioeconomic groups usually consume more vegetables and fruits, which are less energy dense.

While conducting the study we compared the relationship between SBP and DBP with the BMI of studied subjects. The frequency of both systolic and diastolic hypertensions was highest in the obese group whereas the groups with normal or underweight BMI mostly were normotensive. The frequency of systolic prehypertension was highest in the overweight group on the contrary frequency of diastolic prehypertension was found to be higher in the obese group. The observed difference in the BP values between obese and non-obese group may be due to the differences in the BMI values, since high BMI correlates strongly with blood pressures levels of the child [11].

We analyzed the nutritional status of the studied subjects with other well recognized anthropometric markers like WC, WHR and WHtR. 15.6% of the boys and 8.9% of the girls were found to be centrally obese according to waist circumference. WC remains the simplest clinical measure of childhood central obesity. It has been proved a strong predictor of cardiovascular and metabolic disease risk in children [12]. It provides a better estimate of visceral adipose tissue than body mass index (BMI) and is significantly more efficient than BMI in predicting insulin resistance, blood pressure, and serum cholesterol and triglyceride levels [13].

The, WHtR in principle, is a good measure to represent WC in relation to another easily measurable body proportion so that distortions based on the body frame size in different populations are removed. It is being used increasingly to assess the risk of diseases related to central adiposity in adults and WHtR greater than 0.5 has been suggested as a value for indicating whether the upper body fat accumulation is excessive and poses a risk to health in adults [14, 15]. Studies in children using WHtR have also shown that the ratio is superior in its ability to predict cardiovascular disease compared with BMI or percentage body fat [16]. Around 23% of the studied subjects were found to be obese with an almost equal frequency in both gender, these frequency rate was almost similar to the frequency of overweight and obese together on BMI category.

While applying WHR in categorization of nutritional status, 9.4% of the boys and 2.8% of the girls were found to be obese, the rest being normal. WHR has been used to describe body fat distribution in adults; however, it is influenced by several other body factors and is a poor measure of body fat distribution and risk of related diseases in children [17]. When children were classified into different categories in the context of BMI and WC they correlated well with each other but poorly with that as categorized by WHR making it a less suitable tool for diagnosis of obesity in children.

In conclusion, we noticed a fairly high prevalence of obesity among school going children aged 9–14 years in Dhaka. Prevalence of obesity is on rise in Bangladeshi children, highlighting the possible role of change in the dietary pattern and physical activities with increase in income levels. Collective effort of parents and schools and stakeholders are required to institute early preventive measures to reduce March towards obesity and its future cardiometabolic complications.