Prevalence of Underweight , Overweight and Obesity Among Primary School Children in Qatar *

A cross-sectional stratified cluster sample of 4291 children (2187 boys and 2104 girls) aged 6 to18 years attending primary public schools in Qatar was used to determine the prevalence of underweight, overweight and obesity among primary school children in Qatar using BMI as an indicator. Structured questionnaires were used to obtain socio-demographic data. Anthropometric measures were taken by trained nurse. The study revealed a high prevalence of underweight and obesity among Qatari children, with both conditions implicating adverse short and long-term health effects. The prevalence of underweight (BMI < 5% of CDC standard for ageand sex) was 14.6%, overweight (BMI 85% to 95%) was 11.6% and obesity (BMI > 95%) was 14.7% (95% confidence level). The prevalence of overweight and obesity was higher in girls (28.7%) than boys (24%) but was similar in Qatari (26.4%) and non-Qatari children (26.2%). The prevalence of both underweight (15.6%) and obesity (15.8%) were considerably higher in Qatari children.


Introduction:
The "coexistence" of undernutrition and overnutrition has been experienced recently by many of the world's developing countries.This phenomenon has been shown to exist in children (1) and adolescents (2 ' 3) within various population groups.This pattern of health in children is strongly associated with the persistence and adoption of low-quality diets and physical inactivity. 0)n the past, various indices were tried but found wanting.Body mass index (BMI), the index of weight over height squared (BMI) = W t ( k g ) / H t (m2) (2) better reflects the amount of body fat compared with the amount of muscle or bone and is used for measurement of body fatness in adults in the absence of laboratory or radiographic determination.The BMI has good specificity so that it seems to exclude subjects who are not overweight or obese but it can miss some that are obese, i.e. it incorporates poorer sensitivity. (4)ildhood obesity is associated with a number of co-morbidities in childhood (5) and with an increased risk of adult disease, particularly cardiovascular disease and type II diabetes. (6,7)Obese children tend to have lower self esteem than their non-obese peers, and they tend to be more isolated. (8)' 12) This increase in prevalence of obesity has been related to an increasingly sedentary life style with less physical activity and degraded dietary habits.It occurs not only in affluent countries but also in developing countries and countries in the midst of economic transition. (13)There are short-term and potentially long-term health risks (14) associated with undernutrition and lack of catch-up growth. 05,16)The short and long term developmental effects of severe undernutrition in developing countries are well documented °7' 1 8 ) Undernutrition is recognized as an important risk factor for increased prevalence and severity of infection and high mortality rates.WHO estimates that malnutrition (underweight) was associated with over half of all child deaths in developing countries in 1995.°9 ) When designing health programs focusing on malnutrition (undernutrition and obesity), it is essential to understand the magnitude of the problem in young schoolchildren, i.e. the current prevalence.In Qatar few efforts have been made to address this issue and no published study shows the prevalence of underweight and obesity in such an age group.The objective of the present study was to estimate the prevalence of underweight, overweight and obesity in primary school-aged children.If the prevalence is high, effective public health strategies are needed to promote healthy lifestyles and improve diet quality.

Methods: Study population
Following approval from the Supreme Council of Family Affairs (who funded this study) and the Ministry of Education, a study was conducted between April 2003 and May 2004 of 4,291 students selected according to sample size equation for the expected prevalence of obesity (15%) in primary school children in Arabian Gulf Countries.The students studied were randomly selected cluster samples from an available total of 38,070 students in grades 1 through 6 (aged 6 to 18 years) attending primary public schools.From the 112 schools available, five schools for boys and five schools for girls were randomly selected and invited to allow all classes from all grades to participate in the study.
Nine of the ten schools accepted the invitation.

Data collection
Structured questioners were used to obtain information about age, sex, nationality and school name.Anthropometric measures (weight and height) were taken by nine trained school nurses who used calibrated portable scales to measure weight.Subjects wore lightweight clothing and no shoes.Height was measured with a stadiometer attached to the wall, the children being bare foot with their heads held in the Frankfort horizontal plane.

Classification of underweight, overweight and obesity:
Underweight, overweight and obesity were defined according to the sex and age-specific BMI percentile of CDC growth chart (developed by the national center for health statistics in collaboration with the national center for chronic disease prevention and health promotion 2000).Body mass index (BMI) composition was estimated by Wt (kg) /Ht (m2).
The following percentile cut-off points were used: • Underweight -BMI < 5th % • At risk of overweight -BMI between 85%-95% • Overweight -BMI more than 95% For epidemiological (research) purposes: • Overweight was defined as BMI > 85th percentile • Obesity was defined as BMI > 95th percentile Statistical Method: Data management and data analysis were performed by simple descriptive analysis.A chi-square test was conducted to test the association between variables; a Fisher test was used for values < 5; p< 0.05 was considered statistically significant.

Results:
About 60% of the studied children were Qatari, 51 % were male with a mean age of 10 years.The prevalence of underweight among studied population was 14.6%, overweight was 11.6% and obesity was 14.7%.The prevalence of underweight and obesity among Qatari children (15.6% and 15.8% respectively) was higher than Non-Qatari children (13.1 % and 13.2% respectively).
Of those studied, 9.7% of boys and 13.5% of girls were overweight, and 14.3% of boys and 1 5.2% of girls were obese.Overall, there was no difference between boys and girls in obesity.Overweight was more prevalent among non-Qatari children (13%) compared to Qatari children (10.6%) while obesity was more prevalent in Qatari children (15.8%) compared to non-Qatari children (13.2%).The prevalence of obesity and overweight was higher among Qatari girls (28.5%) compared to Qatari boys (24.1 %).Underweight was significantly more prevalent among boys (19.3%) versus girls (9.8%).Among Qatari children, underweight was also more prevalent in boys (21.3%) compared to of Qatari girls (10.3%).

Discussion:
The prevalence of obesity among children has varied greatly over the past decade across different countries, and differences in the definition of pediatric overweight and obesity have made comparisons between studies difficult.
In Qatar, the prevalence of overweight and obesity among primary school children aged 6 to18 years was 11.6% and 14.7% respectively (total 26.3% above 85th% for BMI).These results are in accordance with those reported from Kuwait (1999) with a prevalence of 26.5% (BMI > 90%) among Kuwaiti children aged 6 to 13 year. (20)In the Kingdom of Saudi Arabia (1996) the prevalence of overweight and obesity among Saudi boys age 6 to 18 years was 11.7% and 15.8% respectively/ 21) which is also comparable to our results among Qatari boys (9.2% and 14.9%, respectively).Our data were also in agreement with the prevalence of overweight and obesity in the USA (1988-1994) in children between 6 and 18 years of age (25.6%). (3)Prevalence reports from Sweden and Australia were also in good agreement with our results (23% and 27.5%, respectively). (8' 9)(22 ' 23) However, the prevalence of overweight in Qatari children (10.6%) was lower than that in Chinese children aged 6 to 9 years (11.3% in 1997). (3)Also, the statistics on obesity in the nearby UAE showed a significantly lower prevalence of obesity compared to our data (8%). (4)The prevalence of obesity was higher in Qatari children (1 5.8%) compared to non-Qatari resident children (13.2%), whereas overweight was higher among non-Qatari's (13%) vs. Qatari's (10.6%).
Despite higher prevalence of obesity in Qatari vs. UAE children, overweight prevalence in the UAE was higher in boys and girls (16.5% and 16.9%) compared to Qatari boys and girls (9.2% and 11.9% respectively).The sex difference in obesity trends may relate to tradition since girls may find some restriction to participate in sports activities in a closed community.In Bahrain the prevalence of obesity among those students aged between 12 and 17 years was 21 % in males and 35% in females (using WHO recommended criteria of BMI for age). (25)This was significantly higher than the prevalence of obesity in Qatari's students (14.9% in males and 16.6% in females).Prevalence of overweight and obesity in Australian children aged 7 to 11 years for the year 2000 was 26.2% and 28.4%, in males and females respectively. (23)This prevalence was comparable with our results, 24% and 28.7% in males and females, respectively.
As in many parts of the world, the prevalence of overweight and obesity in Qatari children is alarming.Mean (SD) 10.11 (2) This increase has been related in part to adopting a sedentary life style, change in environmental factors related to socioeconomic, behavioral changes and reduced energy expenditure due to less physical activity.Television watching and computer games are major causes of inactivity and have been linked to childhood obesity.Clearly, a large component of this change is due to increased dietary intake and easy access to energy-dense meals and fast food.The prevalence of underweight among school children in Qatar (14.7%) was comparable to other Asian countries such as China (11.3%) and Russia (10.2%), as well as other developing countries such as Brazil (17.4% among children 6 to 9 years of age in 1997). (3)he prevalence of underweight was higher among Filipino school-age children (32.9%) (26) and Pakistani children (29.5%) (Based on NCHS standard weight for age<2 SD). (27)In rural North India the prevalence of underweight was also much higher among those 12

Table 1 :
Sociodemographic characteristics of children involved in the study (n=4291).

Table 2 :
Pattern of anthropometrics measurement of children under the study (n=4291).

Table 3 :
Pattern of anthropometrics measurements of children involved the study (n=4291).

Table 4 :
BMI mean and SD score for Qatari primary-School age Children 6-12 years (n=2587).age (43.8% in boys and 30.1% in girls) (28) compared to our data in boys 6 to1 2 years of age (19.3%) and girls within the same age range (9.8%).The underweight problem tended to occur more frequently among Qatari and non-Qatari boys (21.3% and 16.6%, respectively) compared to Qatari and non-Qatari girls (10.3% and 8.8% respectively).