July 23, 2020

expert reaction to study looking at TV watching time and health outcomes

An observational study, published in Mayo Clinic Proceedings, has looked at possible associations between television viewing time and poor health outcomes.

Dr Joy Leahy, Statistical Ambassador for the Royal Statistical Society said:

“With observational surveys such as this, we can never be completely sure what is the driving force behind this association.  The authors have adjusted for potential factors such as age, diet, smoker status, etc.  Still, it is always difficult to completely account for everything that could be the cause.  In this study we can see that those who report watching a lot of TV have poorer health outcomes.  Is this because of the TV watching itself?  Is it due to other unhealthy behaviours that go hand-in-hand with watching TV?  Or is it to do with the self-reporting nature of the study?  Are people who are very health conscious more likely to understate the amount of TV that they watch?

“The authors examined replacing TV watching with more physical activities such as walking, moderate and intense physical activity.  I wonder how health outcomes would have fared if TV watching was replaced with more “wholesome” sedentary activities, such as reading a book, or working at a computer.

“The authors are spot on to highlight that it is difficult to identify “the best” amount of TV to watch, due to arbitrary cut off points in other studies.  They use the exact time provided by each person to estimate how much TV is “OK”.  This, I imagine, would be very valuable for governments and health experts when forming recommendations.  However, it is unlikely that one study alone will be strong enough evidence to state definitively that watching less than exactly two hours of TV a day will minimise health risks.”

* ‘Understanding how much TV is too much: A non-linear analysis of the association between television viewing time and adverse health outcomes’ by Hamish ME Foster et al. was published in Mayo Clinic Proceedings on Thursday 23 July 2020.

Declared interests

Dr Joy Leahy: “I’ve no conflict of interest to declare.”