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via The Incidental Economist by Aaron Carroll on 9/28/12
Did that get your attention? That was the intent of this story, entitled, “Study: One Hour Watching TV = Shorter Life By 22 Minutes”. It refers to an upcoming manuscript in the British Journal of Sports Medicine, entitled, “Television viewing time and reduced life expectancy: a life table analysis“:
Background Prolonged television (TV) viewing time is unfavourably associated with mortality outcomes, particularly for cardiovascular disease, but the impact on life expectancy has not been quantified. The authors estimate the extent to which TV viewing time reduces life expectancy in Australia, 2008.
Methods The authors constructed a life table model that incorporates a previously reported mortality risk associated with TV time. Data were from the Australian Bureau of Statistics and the Australian Diabetes, Obesity and Lifestyle Study, a national population-based observational survey that started in 1999–2000. The authors modelled impacts of changes in population average TV viewing time on life expectancy at birth.
Let’s be clear. This is not a randomized, controlled trial. This is an analysis to see if there is a correlation between TV watching and life expectancy at birth. There are any other of a gazillion variables that may confound the analysis. The most obvious, of course, is that people who tend to watch more TV may also engage in unhealthy activities, such as sitting on your butt, not exercising, and eating Cheetos. But here are the results and conclusion:
Results The amount of TV viewed in Australia in 2008 reduced life expectancy at birth by 1.8 years (95% uncertainty interval (UI): 8.4 days to 3.7 years) for men and 1.5 years (95% UI: 6.8 days to 3.1 years) for women. Compared with persons who watch no TV, those who spend a lifetime average of 6 h/day watching TV can expect to live 4.8 years (95% UI: 11 days to 10.4 years) less. On average, every single hour of TV viewed after the age of 25 reduces the viewer’s life expectancy by 21.8 (95% UI: 0.3–44.7) min. This study is limited by the low precision with which the relationship between TV viewing time and mortality is currently known.
Conclusions TV viewing time may be associated with a loss of life that is comparable to other major chronic disease risk factors such as physical inactivity and obesity.
I watch more TV than almost anyone else I know. No joke. But I do it while I’m doing other things. I also exercise regularly and watch what I eat. Does anyone actually believe that it’s the watching TV itself that is shortening your life? From the text of the manuscript:
If these [hazard ratio]s are confirmed, and shown to reflect a causal association, TV viewing is a public health problem comparable in size to established behavioural risk factors.
Really? TV is itself causal? How? Do tell.
I have no problem believing that too much TV is bad for you, in that it can serve as a replacement for an active life, a substitute for good parenting, or as a gateway to unhealthy eating or drinking. But before you can give me a reasonable reason why TV might actively and directly cause you to die earlier, I wish people wouldn’t go there.*
*Note this applies to any number of studies that substitute causation for correlation.
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