I could be wrong, but I thought the RF test was not a good indicator of disease activity. I know that my insurance will not pay for my rheumy to monitor my RF--he can only measure it once a year or so (no more than that). I think if it shoots up from a baseline reading (as you suggested Dave), that can be an indication that the disease has gotten a bit more aggressive. However, it's not a good indicator of treatment success, since a lot of people have a positive RF and do not have RA (it is associated with a variety of different diseases), and even more people have a negative RF (such as you Aldo) but do, in fact, have RA. I believe the actual titer is not as important as whether it meets the cutoff or not (whether it's positive or negative).
My RF is always stubbornly positive, but very low positive (usually in the 20's). Rheumy believes it's meaningful, but exactly what it means we don't know?
Current dx: Rheumatoid Arthritis
Suspected dx: Early Lupus/MCTD
Current Meds: Enbrel, Plaquenil, Aciphex, Ultracet, Zyrtec, Allavert-D, Zantac, Tylenol PM
Past Meds: Relafen, Vioxx, Mobic, Voltaren, Sulfasalazine, Entocort, Prednisone, Humira, Reglan