Parachute use to prevent death, trauma when jumping from aircraft (2018) [pdf]
bmj.com
bmj.com
1: https://johnmjennings.com/can-a-mouse-survive-a-fall-from-a-...
> You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom, it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes.
"A horse splashes". That's some mental imagery right there.
For them other than the cold a drop from 1000 metres is the same as a drop from 10 metres.
However, shrew blankets change the whole scenario to irrelevance--a shrew in a blanket sufficient to keep it safe has very different aerodynamic behavior than a naked shrew.
Just because they don't fall super fast doesn't mean they don't get injured because they don't have as much distance to "drop and roll" like a human does.
They explicitly added the caveat about the soft ground. There'd be very little opportunity for mouses to become comfortable with jumping from high areas as there'd be very few occasions that satisfy the requirement. If the mouse jumped into a cave and can't get out, it'd starve to death. If it jumped off a cliff and fell into water, it would drown. If it fell off a skyscraper, there'd be Asphalt at the ground etc. Off the top of my head, there are no natural places in which mouses could safely get comfortable with jumping. Thus, they'd only do so if they're in mortal danger. And they absolutely do jump off high places if they're terrified
It could be to avoid getting disorientated though, or to be able to see a predator and reverse course...
I can't imagine why the mice would climb trees, but if they did and fall down, they probably gonna be fine most of the time.
In many forests there is lots of large rocks and steep slope/cliffs/precipice in the range 0-5 m where mice possibly could shorten their path by jumping. But I'd suppose they rather use a path they can go in both directions.
It's not how this works, cats are decent swimmers yet they generally refuse to get anywhere close to water…
And then there's the actual vision. Are mice known for being able to see long distance? One could posit, if not then most jumps would be leaps of faith into vague amorphous blobs, full of potential danger and impossible to triangulate or assess.
Why do I wear impractical clothing? I never even thought of it as impractical.
Isn't this how bats have evolved though?
I have a vague recollection of reading that most squirrels have evidence of trauma from falling, such as healed bone fractures.
* * *
We also had a pheasant who routinely visited the garden and one day showed up with a broken leg, that survived for ages before eventually disappearing. Initially he sat quietly in the undergrowth but started hopping around and doing short flights (with clumsy landings). I put out bird seed for him and he incredibly quickly learned to hoot and flap outside my back door when he was hungry. He once followed me into my shed when he was expecting feeding and had to be shoo'd out.
If you go to the Cornell Ornithology Lab feeder cam and scan through the feed at night, you will find flying squirrels at the feeder. They show signs of nocturnal adaptation, another connection to bats.
It could also be because they don't like to change their location too fast. You never know where you could end up. When you fall you might fall next to a cat for instance.
> Parachute use did not significantly reduce death or major injury
I really recommend reading. It is a very funny thing until you realize you've read a few dozen serious articles, well received by a large community (some times even the academic community) with nearly the same kind of arguments.
You can survive the landing. On Titan or Venus. (Surviving the environment is another matter...)
The point being that we should strive for RCTs when possible, and that RCTs carry more weight than expert opinion or case-control. Many (I don’t have an exact number) clinical practice guidelines are based on expert opinion or observational studies, and are completely valid/evidence-based (it’s just weak evidence).
The point of EBM is not “RCT or bust” it’s really more about the hierarchy, that medicine should not practice in defiance of quality evidence and that we should strive to obtain the highest quality evidence possible.
A big problem is that humans have a preference for action, and a dislike of waiting for information.
Many flawed guidelines are based on a desire to act even in the absence of evidence of benefit.
"Primum non nocere" is probably the most accepted but least respected tenant of good medical practice.
Very true, I mostly intended to illustrate that many "good" or accepted guidelines are not necessarily based on randomized controlled trials as there seems to be a misconception (based on recent trending posts) that these are the only forms of "evidence" in medicine.
Some guidelines are borderline pseudoscience but pertinently guidelines are not binding. You point out the correct approach - one is entirely allowed to deviate from guidelines for good reason (i.e. no/very weak evidence, questionable benefit).
That's also the beauty of the EBM, you'll find grade & strength of recommendation in any modern guideline to help interpret them. We also have quality assessment tools like QUADAS-2 and the STARD reporting guidelines to help the reader assess quality.
> "Primum non nocere" is probably the most accepted but least respected tenant of good medical practice.
Also agree but I think EBM addresses this a lot more than the old days of science-based medicine where we did things because "they made sense" without looking at various outcome measures that sometimes reveal missed harm.
> A big problem is that humans have a preference for action, and a dislike of waiting for information.
Part of this is also by necessity due to the nature of patient encounters which have a need for decision-making.
Where the guideline is clearly poor (e.g. adrenal nodules, homeopathic follow-up at best) I disregard them but sometimes you have to err on the side of caution.
As an example I recommend pancreatic cyst follow-up per the ACR guidelines even though my (abdominal radiologist)/institutional expert opinion is they're overkill and unnecessary based on very weak and dated observational evidence. But what's the alternative, everyone just does what they want and a patient's follow-up will be variable depending on the reporting physician?
(Corrected)
I meant "randomized controlled trial" in this case (as the post). "Randomized clinical trial" is often used interchangeably but does not necessarily require a control group (e.g. a non-inferiority study comparing two different treatments).
Controlled means there is a control arm that get no treatment, or treatment as usual (depending on what's needed).
Ideally a Db-rct a doubly blinded randomised controlled trial.
2018: Protagonists of EBM both organized and participated in such a study and found that parachutes don't make any difference in survival when jumping from a plane.
Also in 2018, https://www.cmajopen.ca/content/6/1/E31.full looked at the use of the parachute metaphor in medicine and confirmed most people didn't quite get the joke
“Oh yeah, tough guy? Jump out of this airplane.”
Brilliant.
Both options may be true for different cases. It may be simple to decide on parachutes. But think of bureaucrats who were patting themselves on the head for being “flexible enough and humble enough” to issue new guidance on masks instead of saying “We don’t know” in the first place.
“The sovereign is he who selects the null hypothesis.”
If I'm a passenger in an airliner with no parachute, I definitely don't want my pilot bailing out.
Also, insurance rates on aircraft with airframe parachutes are higher than for aircraft without them - because pilots often panic and pull the chute, which guarantees a hard landing and totals the aircraft, rather than attempting a landing (with, say, a 90% success rate or whatever). The same might apply to individuals: jumping out of a plane is quite dangerous and it might be "statistically" safer to stay onboard and attempt a landing.
Pilots also may take more risks if they have parachutes, known as risk compensation. Like how people drive faster if the car feels safer. https://en.wikipedia.org/wiki/Risk_compensation
Are we sure this isn't because aircraft iwth airframe parachutes are wildly expensive and/or heavily-customized vehicles? I'm not sure the correlation has been established as causative here.
That's option one. Or do you insist on some particular definition of exceptional circumstances?
Option one means treating something like civil law cases. Option two means treating it like criminal law cases.
You are arguing a distinction that does not exist.
Nothing I said implies the opposite.
> You are arguing a distinction that does not exist.
No, the paper framed the issue as if such distinction exists. I didn’t agree with that and I don’t see why you would accuse me of that.
Expensive, yes. Would I like to see it? Heck yes, if nothing else as a way to trick the establishment into doing more replication studies.
What is the set of possible results from the experiment you propose? What function are you going to test: randomness in general, some special RCT event, maybe some doctor who loves to break some double blind experiments?
Parachute use to prevent death, major trauma when jumping from aircraft (2018) - https://news.ycombinator.com/item?id=30795522 - March 2022 (8 comments)
Parachute use to prevent death and major trauma: systematic review (2003) - https://news.ycombinator.com/item?id=28508084 - Sept 2021 (24 comments)
Parachute use to prevent death and major trauma when jumping from aircraft (2018) - https://news.ycombinator.com/item?id=27676727 - June 2021 (6 comments)
Parachute use to prevent death and major trauma related to gravity challenge (2003) - https://news.ycombinator.com/item?id=22788043 - April 2020 (9 comments)
Parachute use to prevent death jumping from aircraft: random controlled trial (2018) - https://news.ycombinator.com/item?id=22778832 - April 2020 (36 comments)
Parachute use to prevent death and major trauma when jumping from aircraft - https://news.ycombinator.com/item?id=18677508 - Dec 2018 (110 comments)
Parachute use to prevent death and major trauma due to gravitational challenge - https://news.ycombinator.com/item?id=4644463 - Oct 2012 (57 comments)
Do some patients benefit from D supplements? Certainly. Yet you can find a group that gains no benefit. In this case we obviously can divide them up but in many cases the division is unknown.
The joke is they’re ruling out the obvious. The headline makes you believe they are stating the obvious (but actually the study is a comment on randomized trials and what kind of research is possible)
Does this result simply mean you just can’t reject the null hypothesis (parachute makes no difference)? Rather than a proof of it?
Statistical significance is a hint that it could be worth running more replication studies, and vary the conditions in other studies. Significance alone does not indicate the effect as real.
So, worst case for parachute wearers is that they are no worse off than without one. Parachutes are safe for use with regards to de-planing.
A minor caveat to our findings is that the rate of the primary outcome was substantially lower in this study than was anticipated at the time of its conception and design, which potentially underpowered our ability to detect clinically meaningful differences, as well as important interactions. Although randomized participants had similar characteristics compared with those who were screened but did not enroll, they could have been at lower risk of death or major trauma because they jumped from an average altitude of 0.6 m (SD 0.1) on aircraft moving at an average of 0 km/h (SD 0). Clinicians will need to consider this information when extrapolating to their own settings of parachute use
Real studies have an equivalent para far too often.
There is no evidence from RCT studies, that parachutes work (this post).
There is no (or only very weak) evidence from RCT studies, that condoms work: https://jech.bmj.com/content/65/2/100
According to the Cochrane Database of Systematic Reviews, there is no evidence from RCT studies, that face masks would protect against respiratory infections: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD...
The point is that the Cochrane review is probably wrong, and face masks do protect, just like parachutes and condoms. And the more general point is to criticize the whole process, that has made half of the Western medical doctors mask skeptics. The point is to say that there are protective equipment that obviously, measurably works, but for which it is difficult to present evidence from RCT-type studies.
Linking their general points from 2018 to specific examples from the recent pandemic, is of course post hoc. But it demonstrates that their notion was not merely theoretical, but important in practice.
They thoroughly researched the effectiveness of parachutes on a pool of candidates at various speeds and altitudes. While the initial pool of candidates covered a variety of situations, for some reason, the pool of participants willing to actually participate in the study was heavily biased towards people in an aircraft standing still on the airport, with about 60 cm from the door to the ground.
The bias may have been further increased by the selection criteria where participants deemed mentally unfit by the investigator were excluded, and willingness to jump from an airplane at altitude with a 50% chance of an empty backpack increased the likelihood of exclusion.
The bottom half of the right column on page 4 explains how this is relevant for real world studies.
I suppose an example would be comparing the death rates of people who'd been on a statin drug for a few weeks to those who weren't on the drug at all. You'd probably find no different in morbidity, which might suggest that statins don't do anything.
> [The study] would use all the best practices
You've go some major contradiction here, since when is such manipulation "the best practice"?
That's the spirit in which I used the term. In plain English: you can correctly apply certain practices that are famously powerful and acceptable, while subtly undermining them in a way people might not notice, or would happily pretend not to notice if the study fits with their political position on the matter.
(Less snarkily, we're all making resource allocation decisions constantly and on the margin those are life or death decisions).
IMHO, on the margins you're allowed to use common sense. Also: your grandma / your grandpa, your resources applies.
Now someone has -- and it turns out they don't have any effect!
It's also possible that the paper criticizes some common features of "scientific" studies.
>The PARACHUTE trial satirically highlights some of the limitations of randomized controlled trials. Nevertheless, we believe that such trials remain the gold standard for the evaluation of most new treatments. The PARACHUTE trial does suggest, however, that their accurate interpretation requires more than a cursory reading of the abstract.
It is part of the 'Christmas edition' of the BMJ which is famous for things like this.
The ideal satire ought to bring up what we should do, ridiculing it. For example, the famous "A Modest Proposal" says that we shouldn't consider taxing the wealthy, particularly the people who make most money from Ireland while not even living there. It insists you couldn't even begin to tackle the problem with taxation or other measures, whereas eating babies would solve the problem entirely.
[shurely some mistake?]
/s
I hope they don't make it mandatory...
An airbag won't do much if you're still going to be squeezed between the engine and tail of the plane at 180 mph.
Want to hide the paratrooper completely - use large, spherical parachutes. Elementary.
Notably this is exactly such a trial, while also absolutely irrelevant to the question of needing a parachute or not (the trial planes were all on the ground at the time of the jumps).
https://healthjournalism.org/blog/2019/02/breakthrough-resea...
This article is part of what is known as the 'BMJ Christmas Edition' which gone on for quite a while[0]. it is meant to be at the same time scientifically serious and practically silly [1]. Its...basically satire, but satire as specific scientific commentary. In this case, about the details and clarity of scientific reporting and the claims made from data.
There have been a couple notable problems...One is that satire and human don't always generalize culturally. The second problem though became much more insidious with the electronic shift in publishing. If you access a Christmas edition article electronically, nothing clearly indicates that anything is different about these articles. Nothing indicates 'Christmas edition'. Nothing indicates that they are meant to be light hearted scientific commentary. So they get cited...both as satire and as not satire. Either for cultural reasons or because people aren't being rigorous.
[0] https://www.bmj.com/about-bmj/resources-authors/article-type...
[1] https://www.statnews.com/2017/12/13/bmj-christmas-issue-stud...