Yahoo! News - Age, Frailty, Parkinson's Complicate Pope's Health: "He is expected to remain in hospital for a few more days.
'It is (due) to a combination of his age, his general frailty and the quite severe Parkinson's that he has,' said Duncan Forsyth, a geriatrician and Parkinson's expert at Addenbrooke's Hospital in Cambridge, England. "

Being 84, frail and having severe Parkinson's can 'complicate' your health. Thanks Doc!