Randomized controlled trial on parachutes vs placebo

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Pyrrho
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Randomized controlled trial on parachutes vs placebo

Post by Pyrrho » Sat Dec 15, 2018 5:35 pm

https://www.bmj.com/content/363/bmj.k5094
Design Randomized controlled trial.

Setting Private or commercial aircraft between September 2017 and August 2018.

Participants 92 aircraft passengers aged 18 and over were screened for participation. 23 agreed to be enrolled and were randomized.

Intervention Jumping from an aircraft (airplane or helicopter) with a parachute versus an empty backpack (unblinded).

Main outcome measures Composite of death or major traumatic injury (defined by an Injury Severity Score over 15) upon impact with the ground measured immediately after landing.

Results Parachute use did not significantly reduce death or major injury (0% for parachute v 0% for control; P>0.9). This finding was consistent across multiple subgroups.
The flash of light you saw in the sky was not a UFO. Swamp gas from a weather balloon was trapped in a thermal pocket and reflected the light from Venus.

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Rob Lister
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Re: Randomized controlled trial on parachutes vs placebo

Post by Rob Lister » Sat Dec 15, 2018 7:59 pm

That was a worthy read.

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xouper
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Re: Randomized controlled trial on parachutes vs placebo

Post by xouper » Sat Dec 15, 2018 9:04 pm

Pyrrho wrote:
Sat Dec 15, 2018 5:35 pm
https://www.bmj.com/content/363/bmj.k5094
Design Randomized controlled trial.

. . . Parachute use did not significantly reduce death or major injury . . .

Also from that study:
The study also has several limitations. First and most importantly, our findings might not be generalizable to the use of parachutes in aircraft traveling at a higher altitude or velocity.
From personal experience and other anecdotes, I feel confident in predicting that their results (highlighted in yellow above) are indeed generlizable to any and all altitudes. This assumes of course that the participants will use the parachutes/placebos in the same manner as described in the study, where the contents of the backpack remains in the pack at all times. Thus it seems safe to predict that the fatality or major injury rate will be about the same for all participants whether the backpack contains a parachute or not.

Perhaps this illustrates another limitation in their study. At no time did any of the participants deploy the parachute from the pack (pull the ripcord, if you will) as part of the test protocols.

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Pyrrho
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Re: Randomized controlled trial on parachutes vs placebo

Post by Pyrrho » Sat Dec 15, 2018 9:44 pm

Clearly, more research is needed. Perhaps a double-blind randomized controlled trial with a much larger study population.

However, in the interest of science:

http://cmajopen.ca/content/6/1/E31.full.pdf+html
In a widely cited 2003 BMJ article, the authors made the tongue-in-cheek observation that there are no randomized trials of parachutes. In an era in which proponents of evidence-based medicine increasingly rely on randomized controlled trials (RCTs) to show treatment efficacy, Smith and Pell argued that some medical practices are so beneficial that it would be silly to subject them to an RCT. The use of a parachute during free fall, such as a controlled jump from an airplane, is an example. Without the use of a parachute, the chance of death approaches nearly 100%, although there are scattered case reports of people surviving such a fall. With a parachute, the risk of death decreases dramatically, with recent estimates of 1.1 deaths per 100000 jumps, a rate of 0.0011%.
Smith and Pell:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC300808/
Objectives To determine whether parachutes are effective in preventing major trauma related to gravitational challenge.

Design Systematic review of randomised controlled trials.

Data sources: Medline, Web of Science, Embase, and the Cochrane Library databases; appropriate internet sites and citation lists.

Study selection: Studies showing the effects of using a parachute during free fall.

Main outcome measure Death or major trauma, defined as an injury severity score > 15.

Results We were unable to identify any randomised controlled trials of parachute intervention.

Conclusions As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute.
The flash of light you saw in the sky was not a UFO. Swamp gas from a weather balloon was trapped in a thermal pocket and reflected the light from Venus.