Written by Taylor Woosley, Staff Writer. According to data assessed from the UK Biobank study, approximately 11% of CHD could be averted if TV viewing time was reduced from ≥2h/day to ≤1h/day, even after accounting for genetic risk, assuming causality.
Cardiovascular disease is currently the leading cause of death worldwide, with coronary heart disease (CHD) and stroke accounting for 84.9% of cardiovascular disease-related deaths 1. Coronary heart disease (CHD) is caused by coronary artery atherosclerosis that causes stenosis of the lumen, leading to myocardial ischemia or necrosis 2. Accumulating studies have supported the role of inflammatory response in the development of CHD and is highly correlated with the accumulation of lipids 3.
CHD is a multifactorial disease resulting from a complex interplay between genetic, behavioral, and environmental factors 4. A number of risk factors like cholesterol, hypertension, smoking, obesity, and sedentary lifestyle contribute to CHD 5. Furthermore, physical activity (≥150 minutes of moderate-to vigorous-intensity) is strongly associated with a reduced risk of CV disease-related morbidity, while excessive sedentary behavior, defined as walking behaviors performed at low energy expenditure (<1.5 metabolic equivalents [METs]) while in seated or reclined postures, has been recognized as being negatively associated with cardiovascular health 6.
To better comprehend the role physical activity has on CHD risk, Kim Y. et al. conducted an observational study using data from the UK Biobank, a large-scale prospective cohort study. The UK Biobank includes data from over 500,000 UK adults aged 40-69 years and includes information on genotype data, demographic information, body composition, and lifestyle behaviors. Subjects (n=373,026) used in the observational study were of white British descent and had no prevalence of CHD and were assessed for genetic susceptibility, sedentary activity levels based on filled out questionnaires which included number of hours spent watching TV, and incidence of CHD. Variables such as age, sex, BMI, unhealthy lifestyle behaviors, smoking status, education, and employment were all included as potential confounders for CHD risk. Cox regression models, using TV viewing or computer use were established, along with confounders with an adjustment for polygenic risk scores and mutual adjustment of TV viewing and computer use were included in the assessment. Significant observational findings from the UK Biobank data are as follows:
- ≤1h/day and 2-3h/day of TV viewing, compared with ≥4h/day of TV viewing, were associated with 16% (95%CI 10-21%) and 6% (95%CI 1-10%) lower hazards of CHD, respectively, after adjusting for potential confounders including genetic risk for CHD.
- HRs of CHD for medium and high genetic predispositions were 1.43 (95%CI 1.36-1.52) and 2.04 (95%CI 1.94-2.15), respectively, compared with those with low genetic predispositions.
- Relative to low genetic risk combined with ≤1 h/day of TV viewing, low genetic risk combined with ≥4 h/day of TV viewing was associated with a 19% (95%CI 3-37%) higher hazard of CHD.
Findings of the observational study suggest that TV viewing was positively associated with CHD risk. This association was independent of individuals’ genetic susceptibility to CHD. Limitations of the study include the lack of causality being drawn due to the observational design of the study, lack of diversity in subjects, the potential for recall bias for amount of time spent watching TV, and the possibility for residual confounding due to unmeasured confounders. Further studies should continue to explore the role between sedentary behavior and risk of CHD.
Source: Kim, Youngwon, Shiu Lun Au Yeung, Stephen J. Sharp, Mengyao Wang, Haeyoon Jang, Shan Luo, Soren Brage, and Katrien Wijndaele. “Genetic susceptibility, screen-based sedentary activities and incidence of coronary heart disease.” BMC medicine 20, no. 1 (2022): 1-11.
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Posted July 25, 2022.
Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.
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