The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial, 2016, Buijze+

[rvallee]

The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial

The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial

Purpose The aim of this study was to determine the cumulative effect of a routine (hot-to-) cold shower on sickness, quality of life and work productivity. Methods Between January and March 2015, 3018 participants between 18 and 65 years without severe comorbidity and no routine experience of...

journals.plos.org

Abstract

Purpose: The aim of this study was to determine the cumulative effect of a routine (hot-to-) cold shower on sickness, quality of life and work productivity.

Methods: Between January and March 2015, 3018 participants between 18 and 65 years without severe comorbidity and no routine experience of cold showering were randomized (1:1:1:1) to a (hot-to-) cold shower for 30, 60, 90 seconds or a control group during 30 consecutive days followed by 60 days of showering cold at their own discretion for the intervention groups. The primary outcome was illness days and related sickness absence from work. Secondary outcomes were quality of life, work productivity, anxiety, thermal sensation and adverse reactions.

Results: 79% of participants in the interventions groups completed the 30 consecutive days protocol. A negative binomial regression model showed a 29% reduction in sickness absence for (hot-to-) cold shower regimen compared to the control group (incident rate ratio: 0.71, P = 0.003). For illness days there was no significant group effect. No related serious advents events were reported.

Conclusion: A routine (hot-to-) cold shower resulted in a statistical reduction of self-reported sickness absence but not illness days in adults without severe comorbidity.

 

[rvallee]

This trial looks like a good example of how flawed randomized trials can be. There was no verification, only 80% of participants actually reported completion. There was no difference in illness, only in sick days, which might be explained by all sorts of confounders. There is a lot of speculation about "immune modulation", and yet it doesn't seem to have been found.

Frankly it's hard to imagine a more error-prone set of methodologies than this. The idea that important decisions are made on the basis of such flimsy evidence is complete madness. It's not about this trial specifically, it's just a good example of how a trivial attempt only ends in misinformation simply because clinicians don't run trials without expecting something out of it. No one runs a clinical trial for an intervention they made up without expecting it to work, and this bias is overwhelming all value out of the entire concept of running trials.

 

[rvallee]

This is really telling and it affects all trials:

Even though the vast majority of participants reported a variable degree of discomfort during cold exposure, the fact that 91% of participants reported the will to continue such routine (and 64% actually did) is perhaps the most indicative of any health or work benefit.

64% reported they did continue, even though 91% reported they would, which guarantees that less than 64% actually did continue. There is something about clinical contexts that encourage lying, on both ends, to make things appear better. It's an overwhelming problem when the effects are this small. And this is in a trial context, imagine how more problematic it is in normal clinical settings. Too much is said to happen with no one actually verifying, and it's all motivated by bias, by wanting some answers more than checking whether they are actually true.

 

[hotblack]

What. They didn’t even measure reports of effectiveness on calming sexual arousal!

Presumably that would have found a reduction in self reported sexual harassment in the workplace.