ANTIPERINUCLEAR FACTOR AND DISEASE-ACTIVITY IN RHEUMATOID-ARTHRITIS, LONGITUDINAL EVALUATION DURING METHOTREXATE AND AZATHIOPRINE THERAPY

Objective. To study the correlation between antiperinuclear factor (AP F) titer and disease activity variables in patients with rheumatoid ar thritis (RA) treated with methotrexate (MTX) or azathioprine (AZA) and to investigate whether changes are dependent on the drug used. Method s. Serial measurements of APF titers (2-fold dilutions) and disease ac tivity variables in a 48-week double blind trial comparing MTX and AZA in 64 patients with RA. APF titers at baseline and during followup, a nd correlations between APF titers and disease activity variables and their changes from baseline were studied in the patient group as a who le and in the 2 treatment groups. Results. The prevalence of the APF a t baseline in the MTX group and in the AZA group with undiluted serum was 15/31 (48%) and 19/33 (58%), respectively. With serum diluted 1:10 this was about 25% higher. The APF titer ranged from 1/10 to 1/640. N o sustained changes in APF titers were observed during followup. Stati stically significant correlations were found between APF titers and 2 of the 4 disease activity variables, as well as for their changes from baseline at some time points and were most pronounced in the AZA grou p. However, no consistent correlation between APF titers and disease a ctivity variables could be established. APF changed from negative to p ositive during followup in 4 patients (6.3%) and from positive to nega tive in 4 (6.3%). Changes in APF titer between 2 consecutive measuring points did not exceed 2 dilution steps. Conclusion. The APF titer sho wed no sustained change during the followup period. There was no consi stent correlation between APF titer and disease activity variables. We conclude that serial measurements of the APE in longitudinal studies do not give additional information.