Published in the BMJ.
The abstract is funny enough, but for the full effect you really ought to read the article. Some delightful snippets:
From the text:
One of the major weaknesses of observational data is the possibility of bias, including selection bias and reporting bias, which can be obviated largely by using randomised controlled trials. The relevance to parachute use is that individuals jumping from aircraft without the help of a parachute are likely to have a high prevalence of pre-existing psychiatric morbidity. Individuals who use parachutes are likely to have less psychiatric morbidity and may also differ in key demographic factors, such as income and cigarette use. It follows, therefore, that the apparent protective effect of parachutes may be merely an example of the “healthy cohort” effect.
From the sidebar:
From the Acknowledgements/Author Contributions/COI Statements:What is already known about this topic
- Parachutes are widely used to prevent death and major injury after gravitational challenge
- Parachute use is associated with adverse effects due to failure of the intervention and iatrogenic injury
- Studies of free fall do not show 100% mortalityWhat this study adds
- No randomised controlled trials of parachute use have been undertaken
- The basis for parachute use is purely observational, and its apparent efficacy could potentially be explained by a “healthy cohort” effect
- Individuals who insist that all interventions need to be validated by a randomised controlled trial need to come down to earth with a bump
Contributors: GCSS had the original idea. JPP tried to talk him out of it. JPP did the first literature search but GCSS lost it. GCSS drafted the manuscript but JPP deleted all the best jokes. GCSS is the guarantor, and JPP says it serves him right.
Competing interests: None declared.
Ethical approval: Not required.