I noticed a usage I consider odd while copy editing, and I'm hoping someone can explain it. Here are two examples from published academic work:
Participants were consented to the study between 13 July 2009 and 14 February 2013, and randomised between 15 July 2009 and 18 February 2013. (link)
Thirteen patients were consented to the study. (link)
Based on the context, I understand them as meaning that the participants consented to the study. However, I find it curious that these samples write in the passive voice rather than the active voice because
I thought consent was only an intransitive verb, which means it can't be passive voice. That's how Merriam-Webster classifies it. To my knowledge, "the researchers consent participants" or "participants consent the study" don't work; "participants consent to the study" does.
Other verbs could work in the passive voice, like "participants were enrolled in the study." But multiple writers have decided to use this phrasing with consent.
My question: Is passive-voice consent a trend or something that is approaching accepted usage, a kind of error that happened to make it past some editors, or something that has been long accepted but not noticed?