It's okay, in theory--Qatar leaves from the same terminal in Chicago that your flight will arrive in from Pittsburgh. But I wouldn't be comfortable w/ a 55 minute connection, so it's like a domestic AA connection at ORD. But the QR flight is after all other international departures (except for a later AA flight to London), so if you miss it your'e probably stuck the night. AA has earlier connections through Chicago--why not just book an AA ticket separately? AA will take care of re-booking your QR flight if anything goes wrong, even on separate tickets.