生物与医学2018bmj.com
跳飞机时使用降落伞预防死亡和重大创伤
Parachute use to prevent death and major trauma when jumping from aircraft
入门 · 约 20 分钟读完前置知识：随机对照试验（RCT）基本概念、基础统计学
导读
这篇发表于 BMJ 的论文以幽默方式进行了“降落伞能否预防跳机死亡”的首个随机对照试验（PARACHUTE 试验）：受试者从停在地面的小型飞机上跳下，结果发现佩戴降落伞并未降低死亡或重伤率。其真实目的是讽刺和揭示 RCT 的方法论陷阱——当社区对某种干预已有强烈信念时，试验往往只招募低风险受试者，从而使结果产生无法挽救的偏倚，外推到真实场景可能造成灾难性后果。
HN 关注点：是因为这篇论文用荒诞的例子精妙地演示了随机对照试验的局限性：既有信念如何影响受试者招募并使结果产生偏倚，这一讨论后来还被引用到新冠治疗（如氯喹）的争议中。
后来怎么样
该论文成为讨论 RCT 方法论局限（尤其是入组偏倚与外部效度）时被广泛引用的经典讽刺案例，并在新冠期间氯喹争议等现实辩论中被双方引用。
HN 评论精选
这几条评论里：支持 1 补充 3
补充指出应读配套编辑评论，解释论文的真实意图是揭示 RCT 因入组偏倚而失真的问题
记得去读配套的编辑评论了解背景：我们进行 PARACHUTE 试验是为了说明在缺乏上下文的情况下解读试验的危险。当社区对标准疗法存在强烈信念时，往往只有低风险患者会入组试验，这会使结果产生无法挽救的偏倚，就像不带降落伞跳机一样。假设这类试验的结果可以推广到更广泛的人群，可能产生灾难性后果。我们并非建议抛弃 RCT，理想情况下新干预都应经过严格的 RCT 评估；但当对未经验证干预的既有信念影响入组人群时，即使设计良好的 RCT 也可能给出误导性结果。
nabla9查看英文原文
Remember to reard the linked editorial for context: https://blogs.bmj.com/bmj/2018/12/13/we-jumped-from-planes-without-parachutes-and-lived-to-tell-the-tale/ > We conducted the PARACHUTE trial to illustrate the perils of interpreting trials outside of context. When strong beliefs about the standard of care exist in the community, often only low risk patients are enrolled in a trial, which can unsalvageably bias the results, akin to jumping from an aircraft without a parachute. Assuming that the findings of such a trial are generalisable to the broader population may produce disastrous consequences. >Before you jump to the conclusion that we’re suggesting we jettison RCTs from clinical research, let us clarify that that is not our intention. In an ideal world, new interventions would always be carefully evaluated through rigorous RCTs before widespread adoption. But when pre-existing convictions about an untested intervention affect the population enrolled, even a well conducted RCT can provide misleading results. Without careful attention to context, extrapolating findings from such an RCT to the patient in front of us may be, well, a leap too far.
支持点明核心结论：高感知风险导致试验入组偏差
这不只是为了搞笑。它证明了当感知风险很高时，'正常人'不会报名参加试验，这会使结果产生偏倚。
calibas查看英文原文
This isn't just for giggles. It's evidence that when there's a high perceived risk, "normal" people don't sign up for trials and it skews the results.
补充总结论文如何巧妙地同时演示 RCT 面临的多重方法论挑战
关于这篇论文的介绍文章可能比论文本身更有信息量。这项研究是一种绝妙的方式，同时展示了多种可能破坏随机对照临床试验的挑战。要点：随机化对评估绝大多数现代疗法的获益与危害至关重要；RCT 容易受到关于标准疗法的既有信念影响，无论这些信念是否合理；当社区存在强烈信念时，往往只有低风险患者入组，使结果产生无法挽救的偏倚；即使是设计良好的 RCT 也可能给出误导性结果。
Reelin查看英文原文
This article about the paper is likely to be more informative than the paper itself. (https://blogs.bmj.com/bmj/2018/12/13/we-jumped-from-planes-without-parachutes-and-lived-to-tell-the-tale/) The study is an absolutely ingenious way of simultaneously illustrating multiple different challenges that can frustrate randomized controlled clinical trials. Some highlights: > We believe that randomisation is critical to evaluating the benefits and harms of the vast majority of modern therapies, most of which are unlikely to be nearly as effective at achieving their end goal as parachutes are at preventing injury among people jumping from aircraft. > RCTs are vulnerable to pre-existing beliefs about standard of care, whether or not these beliefs are justified > When strong beliefs about the standard of care exist in the community, often only low risk patients are enrolled in a trial, which can unsalvageably bias the results, akin to jumping from an aircraft without a parachute. > even a well conducted RCT can provide misleading results
补充引用 Raoult 用该论文类比论证氯喹治疗新冠不应等待 RCT，展示论文在现实争议中的引用方式
让我想起最近对法国 Raoult 教授的采访，他一直在用氯喹治疗新冠。摘录：那些说我们需要三十项多中心研究、纳入一千名患者的人，我要说如果按当前方法学家的规则，我们得重做降落伞的研究——100 人一半带降落伞一半不带，最后数数死了多少。当你有一种疗法在没有任何其他可用疗法时有效，它就应该成为基准。而且开处方是我的自由，不必服从政府命令。
fmjrey查看英文原文
Reminds me of the recent interview of Pr Raoult who's been using chloroquine to treat covid-19 in France. Here's a google translated extract: To those who say that we need thirty multicenter studies and a thousand patients included, I answer that if we were to apply the rules of current methodologists, we would have to redo a study on the interest of the parachute. Take 100 people, half with parachutes and the other without and count the dead at the end to see what is most effective. When you have a treatment that works against zero other treatment available, this treatment should become the benchmark. And it's my freedom to prescribe as a doctor. We don't have to obey government orders to treat the sick. The recommendations of the High Health Authority are an indication, but it does not oblige you. Since Hippocrates, the doctor has done for the best, in the state of his knowledge and in the state of science. https://translate.google.com/translate?sl=fr&tl=en&u=https%3A%2F%2Fwww.upr.fr%2Factualite%2Fpour-comprendre-les-enjeux-du-traitement-du-coronavirus-par-la-chloroquine-nous-vous-conseillons-de-lire-lentretien-du-professeur-raoult-dans-le-parisien-du-22-mars-2020%2F
历次讨论
- 2018Hacker News 讨论帖370 分 · 110 评
- 2020Hacker News 讨论帖53 分 · 36 评
- 2022Hacker News 讨论帖41 分 · 8 评
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