rebeginning interferon at 60

my father has had persistent hepatitis C - 1/b for over 30 years.
Now he's 60 y.o. and his hepatitis is going to be [lightly] active.
On next sunday he'll begin again hinterferon treatment.
5 years ago he tried hinterferon but had to stop because of health 
problems it caused to him, anyway it seemed it was efficient to him 
because his values were decreasing.


Do you have any suggestion for him to evalue before he begins?
Thanks