Beware scientific summaries and abstracts in controversial issues!

It is currently uncertain how much Plan B — the “morning-after” pill, which is a type of emergency contraception — works because of effects that take place after fertilization (i.e. a method ethically completely unacceptable to many, since it would be viewed as destroying a human), rather than (for example) by merely inhibiting ovulation, so that no fertilization takes place.

I pointed out a while back that the scientific papers in this area are being widely misreported. This, alas,  is still continuing. A recent article on Slate by William Saletan (following up on an earlier article) complained about the Vatican’s recent document Dignitatis Personae, where it said:

In order to promote wider use of interceptive methods, it is sometimes stated that the way in which they function is not sufficiently understood. It is true that there is not always complete knowledge of the way that different pharmaceuticals operate, but scientific studies indicate that the effect of inhibiting implantation is certainly present, even if this does not mean that such interceptives cause an abortion every time they are used. …

Saletan complains that “certainly present” is not correct. And if that wording were to be taken in the sense: “utterly beyond question” or “completely verified by a wide range of  studies”, then I would agree with him. However, if it is taken in a sense such as: “current studies point to this”, then I do not.

Saletan points to a 2006 JAMA commentary (i.e. significantly not a peer-reviewed scientific article) which tries to summarize then-current research. This commentary has the same problem as many such commentaries and abstracts: although internal details of the papers referred to are themselves very cautious — because the necessary data doesn’t exist, or only exists in a poorly statistical way — nevertheless the commenter makes it sound as though there are definite conclusions to be found.

For example, the commentary says:

Evidence that would support direct involvement of endometrial damage or luteal dysfunction in Plan B’s contraceptive mechanism is either weak or lacking altogether.

But evidence can be lacking because it has been looked for in many ways, and across many studies, and not found; or it can not exist because the necessary studies are extremely difficult to do, for scientific and ethical reasons, and hence there is simply not much possibility of gathering data. In the current case, it’s the latter. Simply saying “evidence is weak or lacking altogether” fails to represent which situation applies, and thus fundamentally misreports the science. One might just as accurately pick this quote out of the commentary:

women should continue to be informed, as they are now in the Plan B labeling, that its use may affect post-fertilization events

But somehow Saletan fails to pick that quote.

A subsequent 2007 study pointed to evidence that post-fertilization effects are present, and concluded:

Either the actual clinical effectiveness is far lower than has been estimated in the literature to date or mechanisms of action other than ovulation disruption must be contributing
to the clinical effectiveness. In our opinion, both explanations are likely to be contributing to the observed discrepancy between the level of effectiveness that can be attributed to preovulatory effects and the effectiveness reported in clinical trials.

(Alas, also misreported elsewhere.)

Nothing on this is decided, nor is likely to in the near future. Until it is more reasonably decided, beware the summaries and the abstracts.