Research articleTelevision Viewing and Hypertension in Obese Children
Introduction
Childhood obesity is a major health concern in the United States. As of 2004, the National Health and Nutrition Examination Survey (NHANES) estimated that 17% of children and adolescents were obese.1 Obesity is known to increase the possibility of cardiovascular risk factors, such as hypertension.2 Recent studies have shown that cardiovascular risk factors in childhood are significant predictors of preclinical atherosclerosis in adulthood.3 Thus, the increased prevalence of elevated systolic and diastolic blood pressures among U.S. youth over the past 10 years is cause for concern.4 The upward shift of blood pressure in children persists after controlling for population changes in body mass index (BMI).4 Therefore, studies are warranted to assess the contribution of other factors to hypertension in overweight children and adolescents.
Numerous studies5, 6, 7, 8, 9, 10, 11, 12 have shown that time spent watching TV is strongly associated with the risk of being obese in children and adolescents. However, the majority of research has been population-based, which focuses on the risk of being obese versus normal-weight. Little attention has been given to the issue of how TV time is associated with the severity of obesity in obese children. The growing number of obese children worldwide indicates the importance of studying obesity-related issues within this group. Research focusing on an obese population may assist in further identifying prevention and treatment measures for obese children. In addition to the paucity of information available regarding TV time and the severity of obesity, little to no information exists regarding hypertension and TV viewing in obese children. One recent European study did not find an association between TV watching and blood pressure among children9; another found a small association between systolic blood pressure and TV time in boys, but no association in girls.11 However, neither of these studies examined the association between TV viewing and blood pressure among obese children. The current study tested the hypothesis that time spent watching TV is associated with hypertension in obese children.
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Participants
Subjects were children, aged 4 to 17 years, evaluated for obesity at pediatric subspecialty weight management clinics in San Diego CA, San Francisco CA, and Dayton OH, from 2003 to 2005. Data were collected prospectively, with written consent obtained from all parents, and written assent from children aged 8 years and older. Obesity, defined as a BMI greater than or equal to the 95th percentile for age and gender, was an inclusion criterion. Children with a pre-existing diagnosis of
Study Sample
A total of 556 children from three pediatric subspecialty centers met the inclusion criteria for the study. Ten children with missing data were excluded from the analysis. The demographic and clinical characteristics of the remaining 546 subjects (275 boys, 271 girls) are described in Table 1. The mean age for the sample was 11.9 years. The mean BMI was 35.5±9.3 kg/m2 (98.7th±0.8 percentile, z-score=2.54±0.4). Table 1 also shows the distribution of children within the TV-time categories. The
Discussion
In a multicenter study of obese children, the relationship between time spent watching TV and the presence of hypertension was examined. TV time was positively correlated with the severity of obesity. After controlling for the severity of obesity, TV time was independently associated with the presence of hypertension.
This study is the first to demonstrate an association between TV and blood pressure in obese children. Elevated blood pressure in children and adolescents is a growing concern, as
Conclusion
There is a significant association between hours of television watched and both the severity of obesity and the presence of hypertension in obese children. The magnitude of the associations found in this study indicates the need for increased physician and parental compliance to the AAP guidelines for TV viewing. One recent study suggests several strategies to meet these recommendations and to limit negative health outcomes associated with TV viewing; for example, by removing the TV from the
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