Thread by @c0nc0rdance

In 2018, "Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial" was published in the British Medical Journal.

It sought to determine if wearing a parachute when jumping from a plane had any impact on survivability.

It did not.

The study was tongue in cheek to prove a point.

What is easy to miss is that the "tested population" were descending approximately 0.6 m (2 ft) from a plane traveling at 0 m/s.

Wearing a parachute turned out not to prevent any death or injury in either group.

The point being made is that randomized control trials have limitations: equipoise, for one, where
all groups need to have equal opportunity for good outcomes.

In this study, that means jumping 0.6 m from an immobile plane.

In a "real clinical trial", that could mean only enrolling patients with very mild disease, no comorbidities or very young populations.

That's not the reality of clinical practice. It's dangerous to extrapolate from these "safe" trials to real-world outcomes.

There's an unstated lesson that we can apply to current studies on non-pharmaceutical interventions to prevent respiratory disease (masks, especially): sometimes "plausibility" take precedence over provability, especially when only limited trials are even possible.

N95 & KN95 have repeatedly been demonstrated to work in lab experiments, physical demos & the lived experience of BSL-3 workers.

That randomized clinical trials of mask *mandates* don't always detect benefit for a given population & given virus should be taken w a grain of salt.

Do masks work to interrupt the transmission of most respiratory viruses? I'm as confident in that fact as I am that parachutes reduce injury and death when skydiving, regardless of what the headlines say.

The 2018 study is here. My thanks to the authors for such a clear demonstration of an important principle of clinical research.
bmj.com/content/363/bm…