Most medical practices are not parachutes: a citation analysis of practices felt
by biomedical authors to be analogous to parachutes
#MMPMID29343497
Hayes MJ
; Kaestner V
; Mailankody S
; Prasad V
CMAJ Open
2018[Jan]; 6
(1
): E31-E38
PMID29343497
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BACKGROUND: In a 2003 paper in BMJ, the authors made the tongue-in-cheek
observation that there are no randomized controlled trials (RCTs) of parachutes.
This paper has been widely read, cited and used to argue that RCTs are
impractical or unnecessary for some medical practices. We performed a study to
identify and evaluate claims that a medical practice is akin to a parachute.
METHODS: Using Google Scholar, we identified all citations to the 2003 paper. We
searched for claims that a specific practice was akin to a parachute. For each
practice, we identified the desired outcome of the practice, and searched Google
Scholar and ClinicalTrials.gov for RCTs that were conducted, ongoing, halted,
planned or unpublished. RESULTS: Of 822 articles citing the original paper, 35
(4.1%) argued that a medical practice was akin to a parachute. Eighteen of the 35
(51%) concerned mortality or live birth, and 17 (49%) concerned a lesser outcome.
For 22 practices (63%), we identified 1 or more RCTs: in 6 cases (27%), the
trials showed a statistically significant benefit of the practice; in 5 (23%),
the trials rejected the practice; in 5 (23%), the trials had mixed results; in 2
(9%), the trials were halted; and in 4 (18%), the trials were ongoing. Effect
size was calculated for 5 of the 6 practices for which RCTs gave positive
results, and the absolute risk reduction ranged from 11% to 30.8%, corresponding
to a number needed to treat of 3-9. INTERPRETATION: Although there is widespread
interest regarding the BMJ paper arguing that randomized trials are not necessary
for practices of clear benefit, there are few analogies in medicine. Most
parachute analogies in medicine are inappropriate, incorrect or misused.
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