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Original Article

Causal Relationship between Television Viewing Time, Cardiovascular Diseases, and Potential Mechanisms

Mengjin Hu et al. Boyu Li Jinggang Xia Chunlin Yin Yuejin Yang

Abstract

Background:

As the predominant leisure-time sedentary behavior, television viewing was documented to increase cardiovascular diseases in observational studies, yet the causal relationship and potential mechanisms remain to be determined.

Objectives:

To systematically investigate the causal relationship between television viewing time, cardiovascular diseases, and potential mechanisms.

Methods:

We conducted a two-sample Mendelian randomization (MR) analysis to estimate causal associations with cardiovascular diseases and biomarkers of cardiometabolic risk. The random inverse-variance weighted method was used as the primary estimate. To account for multiple comparisons, a Bonferroni correction p value for cardiovascular diseases and biomarkers of cardiometabolic risk was 0.0045 and 0.0024, respectively.

Results:

Genetically instrumented television viewing time was associated with higher risks of type 2 diabetes (odd ratio [OR]=2.51; 95% confidence interval [CI]: 1.89-3.33; p<0.00001), hypertension (OR=2.11; 95% CI: 1.67-2.66; p<0.00001), coronary heart disease (OR=1.53; 95% CI: 1.23-1.91; p=0.00015), and heart failure (OR=1.42; 95% CI: 1.18-1.70; p=0.00017). Suggestive evidence of harmful associations was also observed for peripheral artery disease (OR=1.58; 95% CI: 1.07-2.34; p=0.02253) and ischemic stroke (OR=1.34; 95% CI: 1.10-1.63; p=0.00328). Biomarkers of cardiometabolic risk, including interleukin 10, leptin, visceral adipose, abdominal subcutaneous adipose, liver fat, body mass index, waist circumference, triglycerides, and C-reactive protein, were increased. Systolic blood pressure, heart rate, low-density lipoprotein, and total cholesterol were potentially increased while high-density lipoprotein was decreased. However, television viewing time had no effect on venous thromboembolism or pulmonary embolism.

Conclusion:

Television viewing time was causally associated with increased risks of cardiovascular diseases, which may be explained by metabolic and inflammatory mechanisms.

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Artigo Original

Physical inactivity, TV-watching hours and body composition in children and adolescents

Ivan Romero Rivera et al. Maria Alayde Mendonça da Silva Renata D'Andrada Tenório Almeida Silva Bruno Almeida Viana de Oliveira Antonio Carlos Camargo Carvalho

BACKGROUND: Physical inactivity is a predisposing factor to the onset/worsening of other cardiovascular risk factors, particularly obesity. OBJECTIVE: To determine physical activity level (PAL) and daily number of hours of TV (HTV) and the association and/or correlation of these variables with age, gender, economic class, public/private school, overweight and obesity in children and adolescents. METHODS: Cross sectional study, school-based population, public and private education, primary and secondary education. The sample was calculated based on the minimum expected prevalence of several variables, including physical inactivity. Cluster sampling. Protocol: structured questionnaire, including Physical Activity for Older Children Questionnaire (PAQ-C) measurements of weight, height, body mass index (BMI) and triceps skinfold (TSF). Statistical analysis: Chi-square, linear correlation. RESULTS: Among the 1,253 students, averaging 12.4 ± 2.9 years old, of which 549 were male, there was a prevalence of inactivity in 93.5%, more commonly found in female adolescents and there was no association between PAL and excess weight or body fat, soccer and dance were the most frequent activities in boys and girls, respectively; 60% of students did not have physical education classes. Average and median HTV were respectively 3.6 and 3 hours; there was a significant association between HTV and obesity and significant correlation between PAL and age (negative) and between BMI and TSF (positive). CONCLUSION: Physical inactivity is present in 93.5% of children and adolescents from Maceió. It is more commonly found among teenagers and females, with no association or correlation of this variable with excess weight or body fat; obesity was associated with > 3 HTV.