The tuberculin skin test (TST) has recently been proposed as a screening procedure for latent TB prior to anti-tumor necrosis factor (TNF) alpha therapy. Our aim was to evaluate TST levels in patients receiving anti TNF alpha due to ankylosing spondylitis (AS) and rheumatoid arthritis (RA).
73 AS patients (52 male, 21 female) and 33 RA patients (11 male, 22 female) were enrolled in the study. Patients' clinical and demographic characteristics were recorded. Average age +/- standard deviation was 38.8 +/- 7.2 years for AS and 40.7 +/- 13 for RA. Median number of immunosuppressive agents used was 1 (min-max) (0-2) in AS and 2 (2-3) in RA. To determine the activity of the disease, BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) was measured in AS patients, and DAS 28 (Disease Activity Index) was used in RA patients. TST was performed using the Mantoux method in all patients.
Mean BASDAI was 5.1 +/- 0.8 in AS, and DAS 28 score in RA was 5.7 +/- 0.5. Both, AS and RA patients had active disease. TST values were higher in AS than in RA patients. TST values were 11.5 +/- 6.5 mm in AS patients, compared to 7.0 +/- 6.4 mm in RA patients. A positive correlation between disease duration and TST was determined in AS patients. There was also a weak correlation in RA patients between immunosuppressive use and TST (r = 0.37, p = 0.032). No correlation was determined with disease activation in AS or RA patients.
This is the first study to evaluate the correlation between the use of multiple immunosuppressive agents and TST. We determined that TST is correlated with disease duration in AS and with the use of multiple immunosuppressive agents in RA (Tab. 3, Ref. 21).