Health Division, Fundación FES Social, Bogota, Colombia
Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
Department of Evaluation, PROFAMILIA, Bogota, Colombia
Non Communicable Diseases Unit, Pan American Health Organization, Washington, D.C., USA
Escuela de Medicina. Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
Department of Evaluation, Centro de Estudos do Laboratório de Aptidão Física de São Caetano do Sul, São Caetano do Sul, Brazil
Research Division, Instituto Colombiano de Bienestar Familiar, Bogota, Colombia
Abstract
Background
There has been an ongoing discussion about the relationship between time spent watching television and childhood obesity. This debate has special relevance in the Latin American region were the globalization process has increased the availability of screen-based entertainment at home. The aim of this study is to examine the association between television viewing and weight status in Colombian children.
Methods
This cross sectional investigation included children aged 5 to12 yrs from the National Nutrition Survey in Colombia (ENSIN 2005). Weight and height were measured in 11,137 children in order to calculate body mass index. Overweight was defined by international standards. Time spent viewing television was determined for these children through parental reports. Multiple logistic regression analyses were conducted for different subgroups and adjusted for potential confounders in order to study the association between television viewing and weight status in this population.
Results
Among the surveyed children, 41.5% viewed television less than two hours/day; 36.8% between two and 3.9 hours/day and 21.7% four or more hours/day. The prevalence of overweight (obesity inclusive) in this population was 11.1%. Children who were classified as excessive television viewers (between two and 3.9 hours/day or 4 or more hours/day) were more likely to be overweight (OR: 1.44 95% CI: 1.41–1.47 and OR: 1.32 95% CI: 1.30–1.34, respectively) than children who reported to watch television less than 2 hours/day. Stratified analyses by age, gender and urbanization levels showed similar results.
Conclusion
Television viewing was positively associated with the presence of overweight in Colombian children. A positive association between urbanization level and television viewing was detected. Considering that the majority of Colombian children lives in densely populated cities and appear to engage in excessive television viewing these findings are of public health relevance for the prevention of childhood obesity.
Background
Childhood obesity is associated with the presence of cardiovascular disease risk factors such as hyperlipidemia, hypertension, glucose intolerance, as well as their clustering
The prevalence of childhood obesity has reached epidemic proportions in developed nations
Rapid processes of industrialization coupled with accelerated epidemiologic and nutritional transitions have been linked to the rising prevalence of childhood obesity in developing countries
Despite the fact that increases in the prevalence of childhood obesity have been documented worldwide and that time devoted to TV viewing has been implicated in these trends, there is little information regarding the association between TV viewing and obesity in Latin America children
Consequently, the aim of this study is to examine the association between TV viewing and overweight (obesity inclusive) in a representative sample of 5–12 y old Colombian children living in both rural and urban areas.
Methods
Study design
The present investigation used data from the National Nutrition Survey in Colombia (in Spanish:
Seventy nutritionists received a standardized training prior to data collection with 62 of the 70 being selected as interviewers. Thirteen nutritionists were also specifically trained to take anthropometric measures.
Measurement of the dependent variable
Weight and height were taken directly at the children's homes using standardized measuring equipment and with children in light clothing and shoes removed. Body weight was measured to the nearest 0.1 kg using a calibrated digital scale (SECA model 770) which was properly adjusted for the Colombian geographical latitude. Height was measured to the nearest 1.0 cm using a portable stadiometer (Shorr Productions). BMI was computed by dividing body weight by height squared (kg/m2). Overweight (obesity inclusive) was defined using the gender and age-specific cut-off points for BMI adopted by the International Obesity Task Force
Measurement of TV viewing
TV viewing and video game use were determined by asking the following question: "
Based on the combined TV viewing and video-game use information, children were then classified into three groups: less than two hours per day, 2 to 3.9 hours per day, and four or more hours per day. Current public health and clinical recommendations regarding TV viewing in the pediatric setting informed the selection of this threshold (≥ 2 hours/day) to study its effects on children's weight status
For the purposes of this study, we only refer to TV viewing since the majority of the children belonged to low SES groups and did not have access to video-games.
Measurement of covariates
The following covariates were included, age (stratified in two groups 5 to 8 years and 9 to 12 years), gender, urbanization levels, and socioeconomic strata (SES) of the family. Based on their population density, cities and towns included in the study were divided into four urbanization levels. Urbanization level I included mostly rural settlements with 10,000 inhabitants or less. Urbanization level II included cities or towns with 10,001 to 30,000 inhabitants. Urbanization level III were cities with 30,001 to 100,000 inhabitants and urbanization level IV were cities with more than 100,000 inhabitants.
The SES of the child's family was determined according to the national SISBEN index which takes into account socio-demographic characteristics (family composition, employment status, family income, and education level), living conditions (construction type and materials), and access to public utilities (sewer, electricity, potable water and garbage collection)
Statistical analysis
The distribution of selected covariates by TV viewing group was evaluated using Pearsons' Chi square test. The association between TV viewing and overweight (obesity inclusive) was assessed using multiple logistic regression analysis while adjusting for potential confounders (gender, age groups, SES and urbanization levels). In addition, stratified analyses were performed by age, gender, urbanization level, and SES of the family. Collinearity was examined using regression diagnostic tests including variance inflation factor (VIF) with their values always less than 0.99
Results
Study population characteristics
Gender distribution for the study sample (n = 11,137) was approximately equal (49.9% males) and the mean age was 8.5 y (SD = 2.28) with 50.3% of the children being in the 9–12 y old range. Approximately 41.1% of the children were in the lowest SES. Most of the surveyed children (71.3%). lived in rural areas and urban settlements with populations of less than 10.001 inhabitants
Prevalence of TV viewing
For the study population 41.5% of parents reported their child's TV viewing level to be < 2 hours/day, 36.8% between 2 and 3.9 hours/day, and 21.7% to be 4 or more hours/day. Excessive TV viewing (≥ 2 hours/day) was more prevalent among older children (62.6%; p < 0.001), males (60.6%; p < 0.001), those with middle to high SES (levels 3 – 6; 66.5%; p < 0.001), and in children living in the most urbanized areas (level IV; 71.3 %; p < 0.001) (Table
Prevalence of television viewing by sociodemographic characteristics among 11,137 children aged 5 to 12 years. Analysis conducted from the National Nutrition Survey (ENSIN) Colombia. 2005
Characteristics
n*
< 2 hrs/day
2 – 3.9 hrs/day
≥ 4 hrs/day
P**
SE
P**
SE
P**
SE
All participants
11,137
41.5
0.03
36.8
0.02
21.7
0.02
Age groups, yrs
5–8
5,539
45.7
0.04
34.8
0.02
19.5
0.02
< 0.001
9–12
5,598
37.4
0.03
38.7
0.03
23.9
0.02
Sex
Male
5,568
39.4
0.05
38.1
0.03
22.5
0.03
< 0.001
Female
5,569
43.6
0.03
35.4
0.02
21.0
0.02
Socio Economic Status
Level 1 (Lowest)
4,576
56.0
0.04
28.9
0.03
15.1
0.02
< 0.001
Level 2
4,124
34.7
0.04
41.1
0.03
24.2
0.03
Level 3 to 6 (Middle – high)
2,437
33.5
0.05
40.3
0.04
26.2
0.03
Levels of urbanization
Level I (rural and urban areas with 10.00 inhs or less)
7,946
51.1
0.04
32.9
0.03
16.0
0.03
< 0.001
Level II (10.001 to 30.000 inhs)
833
30.4
0.01
42.1
0.01
27.5
0.01
Level III (30.001 to 100.000 inhs)
1,292
33.7
0.08
39.4
0.07
26.9
0.03
Level IV (more than 100.000 inhs)
1,066
28.7
0.01
42.1
0.01
29.2
0.01
*Unweighted sample size.
**Weighted percentage (P) and standard error (SE)
Prevalence of overweight
Of the studied children, 11.1% were classified as overweight (obesity inclusive) with a higher prevalence among younger children (5–8 y: 11.3%; p < 0.001), those living in the most urbanized areas (level III and IV: 14.1% and 14.6% respectively; p < 0.001), and those in middle to high SES level (levels 3–6: 17.2 %; p < 0.001) (Table
Prevalence of overweight (obesity inclusive) by selected sociodemographic characteristics and television viewing among 11,137 children aged 5 to 12 years. Analysis conducted from the National Nutrition Survey (ENSIN) Colombia. 2005
Characteristics
P*
SE
All participants
11.1
0.05
Age groups, yrs
5–8
11.3
0.08
< 0.001
9–12
10.9
0.06
Sex
Male
10.0
0.08
< 0.001
Female
12.2
0.04
Socio Economic Status
Level 1 (Lowest)
5.0
0.08
< 0.001
Level 2
11.8
0.06
Levels 3 to 6 (Middle-high)
17.2
0.05
Levels of urbanization
Level I (rural an urban areas with 10.000 inhs or less)
8.5
0.07
< 0.001
Level II (10.001 to 30.000 inhs)
11.6
0.03
Level III (30.001 to 100.000 inhs)
14.1
0.09
Level IV (more than 100.000 inhs)
14.6
0.01
Television viewing exposure levels
< 2 hrs/day
8.5
0.05
< 0.001
2 – 3.9 hrs/day
13.5
0.10
4 or more hrs/day
13.0
0.05
*Weighted percentage (P) and standard error (SE)
Associations between TV viewing and overweight
In the logistic regression models, children classified as excessive TV viewers (2 to 3.9 hours/day or 4 or more hours/day) were more likely to be overweight (OR: 1.44 95% CI: 1.41–1.47 and OR: 1.32 95% CI: 1.30–1.34, respectively) than those who watched less than 2 hours/day. This pattern of association was also found in analysis stratified by gender, age and urbanization levels. (Table
Odds Ratios for overweight (obesity inclusive) by sex, age groups, and urbanization levels among 11,137 children aged 5 to 12 years, Analysis conducted from the National Nutrition Survey (ENSIN) Colombia. 2005
Television viewing exposure levels
Adjusted OR
95% CI
a
Total population
< 2 hrs/day
1.00
Referent
2 – 3.9 hrs/day
1.44
(1.41–1.47)
< 0.001
≥ 4 hrs/day
1.32
(1.30–1.34)
< 0.001
b
All males
< 2 hrs/day
1.00
Referent
2 -3.9 hrs/day
1.51
(1.46–1.56)
< 0.001
≥4 hrs/day
1.38
(1.34–1.42)
< 0.001
b
All females
< 2 hrs/day
1.00
Referent
2 -3.9 hrs/day
1.39
(1.34–1.44)
< 0.001
≥ 4 hrs/day
1.29
(1.26–1.32)
< 0.001
c
All children aged 5 to 8 ys
< 2 hrs/day
1.00
Referent
2 -3.9 hrs/day
1.19
(1.15–1.22)
< 0.001
≥ 4 hrs/day
1.32
(1.29–1.36)
< 0.001
c
All children aged 9 to 12 ys
< 2 hrs/day
1.00
Referent
2 -3.9 hrs/day
1.78
(1.73–1.84)
< 0.001
≥ 4 hrs/day
1.40
(1.36–1.43)
< 0.001
d
Level I (rural and urban areas with 10000 inhabitants or less)
< 2 hrs/day
1.00
Referent
2 -3.9 hrs/day
1.29
(1.24–1.34)
< 0.001
≥ 4 hrs/day
1.49
(1.46–1.52)
< 0.001
d
Level II to IV (10001 inhabitants and more)
< 2 hrs/day
1.00
Referent
2 -3.9 hrs/day
1.56
(1.53–1.60)
< 0.001
≥ 4 hrs/day
1.26
(1.24–1.29)
< 0.001
a Adjusted by sex, age groups, SES and urbanization levels.
b Adjusted by age groups, SES and urbanization levels.
c Adjusted by sex, SES and urbanization levels.
d Adjusted by sex, age groups and SES.
In addition, the strength of association between TV viewing and weight status was greater for those in the 2 – 3.9 hours/day group than for those in the 4 or more hours/day group, with the exception of the 5 to 8 y old group and those who lived in rural areas and urban settlements of less than 10,001 inhabitants.
Discussion
In this study we found a positive association between excessive TV viewing and the presence of overweight among Colombian children. This association was observed for children of different gender, age groups (5–8 and 9–12 y old) and for children living in different urbanization levels.
The magnitude of the associations detected between TV viewing groups and weight status ranged from (OR) 1.32 to 1.44 for the total sample and from 1.19 to 1.78 in the sub-group analyses. Previous studies exploring the association between electronic media use and health-related outcomes have found conflicting results. Some investigations have not detected significant associations
Among children aged 5–8 yrs and children living in rural or urban areas with less than 10,001 inhabitants, we found increasing odds for overweight as TV viewing increased. The stability of the estimates we obtained for the association between weight status and TV viewing may have been affected by information biases related to this last variable. For example, a recent study indicates that having a TV in the children's bedroom should become an important control variable in studies where estimates are obtained by proxy report
Parental reports of TV viewing time in older children (9–12 y old) might not be as adequate because these children are more independent than their younger counterparts and their parents could have less control over their daily activities, thus overestimating their TV viewing time.
Similarly, the quality of information regarding TV viewing time might be better for children of low SES living in rural or small urban settlements where, in most of the cases, there is only one TV. In such cases parents will probably have a better idea of their children's TV viewing time. More detailed information on the children's TV viewing patterns will be an important addition to future studies exploring health-related effects of TV viewing and other electronic entertainment. While the effect of excessive TV viewing time on adiposity could be explained by the displacement of physically active pursuits and/or increases in energy intake while viewing TV,
The findings of this study point to the existence of a positive association between the level of urbanization with both TV viewing time and prevalence of childhood obesity. The fact that the most urbanized areas have more access to television as an indirect result of the globalization process might explain these results. The Latin American region is urbanizing at an extremely rapid pace. Currently, 75% of the population lives in urbanized areas and it is predicted that this proportion will increase to 84% by 2030
Several strengths can be identified in this study. To our knowledge, this is the first investigation to explore the association between TV viewing and overweight in a national representative sample of children from a Latin American country. The use of data from a national survey allowed us to contrast the association between TV viewing and weight status by children living in different urbanization levels and SES. The study previously conducted in Mexico was restricted to children who resided in the Federal District
Conclusion
Time spent in sedentary activities in particular TV viewing is emerging as a risk factor for different health outcomes in children including obesity and related cardio-metabolic disarrays. There is a growing concern that rapid processes of globalization and urbanization occurring in developing regions like Latin America will impact the prevalence of childhood obesity in part as a result of increased availability of television at home. Our findings suggest that TV viewing is positively associated with the presence of overweight and obesity among Colombian children. At the same time, both TV viewing and the prevalence of overweight were found to be positively associated with urbanization level. The public health implications of these findings are considerable, since the majority of Colombian children live in densely populated areas and engage in excessive TV viewing. These trends are a call for action for the development and implementation of programs and national policies for the prevention of childhood obesity in Colombia and the Latin American region. An important component of such programs should be strategies to limit TV viewing among children and adolescents
Competing interests
The author(s) declare that they have no competing interests.
Authors' contributions
LFG conceived the study and participated in the analysis and drafting of the manuscript. DP and FL participated in the analyses and interpretation of data and in the drafting of the manuscript. BS, JM and DL provided valuable comments in the analyses and discussion sections of the manuscript. EJ, SM, CB contributed in data collection protocol for ENSIN and provided valuable comments in the drafting of the manuscript. All authors read and approved the final manuscript
Acknowledgements
This work was supported by the Family Welfare Colombian Institute and PROFAMILIA. The authors are grateful for the valuable comments provided by Gabriel Ojeda, Luz Mariela Manjarres and Orlando Scoppetta.