Discover and read the best of Twitter Threads about #bicyclehelmet
Most recents (1)
I find this quite interesting; the estimates for the association between wearing a #mask and some coronavirus infection in non-hc setting (0.56, 95% CI: 0.40-0.79) is roughly the same magnitude as the association for #bicyclehelmet and head injury (0.49, 95% CI: 0.42-0.57) 1/9 
Are they both confounded? You bet. But they're also both mechanistically plausible. And there's some major issues with conducting RCTs for both. Ethical reasons for helmets, and for masks, statistical power issues (adherence, sample size, disease prevalence) seem pretty bad 2/9
With helmets, the people wearing them probably have some different characteristics than non-users, that causes confounding. Probably they're more cautious and take less risks in traffic. It's also possible that for some individuals, helmet causes risk compensation... 3/9
