The Adam story - at the time in Sydney, ZooTV was a huge story across the board, and the movements of the U2 members were kind of the celebrities-in-town focus of the gossipy columns in the papers and radio and all that.
They (U2) actually publicly announced (I think, from memory, even before they went on stage) that Adam was suffering a '24 hour virus', which as it is, takes no level of genius to read through. But within minutes of that message getting announced, people were ringing into Triple M (at the time the largest radio station in Sydney, and always the biggest U2 supporters) and telling stories of "Bullshit! I met him at 4am this morning outside X club, and he was fucked!" I can't remember any of the details, but in the days afterwards, quite a bit of the 'Adam Clayton's Bender' story was pieced together and out there at the time.
From memory it wasn't anything extraordinary. A bit of a self destructive drug'n'booze bender that went on for too long into the next day. Probably more just a case of him still being too far off his tits come game time then any kind of heart stopping medical emergency. And in At the End of the World, the band don't seem too worried, they just seem pissed off. That sounds like a reaction to someone just really fucking up, not, you know, dying.