Limited prognostic value of changes in antineutrophil cytoplasmic antibody titers in patients with Wegener's granulomatosis.

One hundred and six patients with Wegener's granulomatosis (WG) were studied for the presence of antineutrophil cytoplasmic antibodies (ANCA). In 53 patients serial ANCA determinations were obtained. C-ANCA positivity was a sensitive (88%) marker of active WG. However, changes in serial titers were temporally concordant with a change in disease status in only 55% of patients. Furthermore, a rise in c-ANCA titer preceded clinical exacerbation of disease in only 24% of patients who had been in remission or had low grade, smoldering disease. A rise in c-ANCA titer alone should not be considered a priori evidence of impending relapse, and does not justify modification of immunosuppressive therapy.