Is jumping out of plane without a parachute dangerous?
Suppose that the folks at the Cochrane Review searched the scientific literature for randomized controlled trials that compared jumping out of plane with and without a parachute. Not surprisingly, there aren’t many studies like that.
Suppose that they discovered one study that looked at 11 people who jumped out of planes with and without parachutes. Any study that looks at only 11 people isn’t large enough to draw any conclusions. Would it therefore be acceptable for them to write the following?
There is no strong evidence from randomized trials to favor jumping either with or without a parachute.
Would it be acceptable for them to send out the following press release?
A new Cochrane Review concludes that all countries should consider allowing people to jump out of planes without parachutes.
That would be idiotic, right? The best thing we could say about such a study is that it is shockingly irresponsible. When randomized trials cannot be performed because letting people jump out of planes without parachutes would be unethical, we are not entitled to conclude that there is no evidence to favor jumping with or without parachutes. We are not entitled to conclude anything at all. So any study that drew that conclusion would be a piece of garbage.
That’s why the folks at the Cochrane Review owe the scientific community an abject apology for publishing a “study” on homebirth that amounts to a piece of garbage.
Homebirth advocates including the Midwives Alliance of North America are declaring that the Cochrane Review on homebirth shows that “planned home birth…as safe as planned hospital birth…w/ less intervention & fewer complications.”
But it doesn’t show anything of the kind. In fact, it doesn’t show anything at all.
Here’s a typical media report on the study:
A new Cochrane Review concludes that all countries should consider establishing proper home birth services. They should also provide low-risk pregnant women with information enabling them to make an informed choice. The review has been prepared by senior researcher, statistician Ole Olsen, the Research Unit for General Practice, University of Copenhagen, and midwifery lecturer PhD Jette Aaroe Clausen…
The updated Cochrane Review concludes that there is no strong evidence from experimental studies (randomised trials) to favour either planned hospital birth or planned home birth for low-risk pregnant women. At least not as long as the planned home birth is assisted by an experienced midwife with collaborative medical back up in case transfer should be necessary.
There’s no strong evidence because there is no evidence at all.
Here’s what the Review actually showed:
Main results
Two trials met the inclusion criteria but only one trial involving 11 women provided some outcome data and was included. The evidence from this trial was of moderate quality and too small to allow conclusions to be drawn. (my emphasis)
Authors’ conclusions
There is no strong evidence from randomised trials to favour either planned hospital birth or planned home birth for low-risk pregnant women.
No, there is no evidence PERIOD. Therefore no conclusion can be drawn PERIOD.
Well, actually there is one conclusion that can be drawn:
The Cochrane Review wants to promote homebirth. Therefore, they published a “study” written by homebirth advocates that included no data, but nevertheless concluded that homebirth is safe.
It’s been established that Cochrane Childbirth Reviews are riddled with statistical errors. But the Reviews have sunk to a new low with the publication of this homebirth “study” that is nothing more than the personal opinions of the partisan authors. The folks at the Cochrane Review should be ashamed of themselves.
