Parachutes don’t save lives?

Not when the jumper starts only 2 meters from the ground.

“Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial
BMJ 2018; 363

“”Ah, but the method of madness matters! The non-participating passengers flew at 800 km/hr at an altitude of 9,146 m, but the trial participants jumped a whopping 0.6 meter (2 feet) from a plane traveling at an incredible 0 km/hr. The authors point out their trial’s glaring limitation — an inability to generalize to higher altitude jumps — and use it make a point that health journalists would be wise to remember:

“When beliefs regarding the effectiveness of an intervention exist in the community, randomized trials might selectively enroll individuals with a lower perceived likelihood of benefit, thus diminishing the applicability of the results to clinical practice.

This study was conducted in response to a Christmas, 2003 BMJ article decrying the lack of RCT (Random Controlled Trials) for the efficacy of parachutes. As the authors of this article point out, even RCT’s have their limits.

As one review explains,

Put plainly, if most people already think an intervention works, then an RCT may end up with enough bias in its design that the conclusion ends up clinically meaningless. Sometimes, an RCT is truly unethical, and other times an RCT really might be needed to test an intervention taken for granted. Health journalists should scrutinize an RCT’s methods closely.

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