Are we sure they didn't ask, but just decided not to report the results?
I'm not aware of a published protocol but it wasn't mentioned in the methods section of the long-term follow-up paper.
It would also have been a great opportunity to ask about employment, benefits, lost hours, etc. rather than the purely subjective measures that they used. But at that point it was no longer a randomised trial so maybe the biggest surprise is that they bothered following up at all.
What a waste of £5m of taxpayers' money - blowing the randomisation, as a deliberate choice.