Hi Mary,
I'm no longer at 70 or over... but I was for a bit in college! At that time I was on IV antibiotics 2 - 3 times per year. I was just encountering too many illnesses living away at school... plus I'd probably miss a treatment here and there, too. Now that I'm working full time, my FEV1 is lower, but I'm on IV antibiotics only once a year or once every other year. I'd attribute this to my total unwavering compliance and limited exposure to 'germy' places!!
Point is, I don't think FEV1 and number of infections always coincides...
Hope this helps!...
Kris
26 w CF