Background Cytotoxic or anti-TNF therapies increase risk of reactivation of latent tuberculosis infection (LTBI). Therefore screening for latent tuberculosis is mandatory before initiating therapy. On the other hand, these patients who are candidate for cytotoxic or anti-TNF therapies are already on corticosteroid or immunosuppressive treatments. These treatments give rise to false-negative tuberculin skin test (TST) results. It has been reported that interferon-gamma release assays tests have a higher sensitivity on receiving corticosteroid or immunosuppressive treatments.
Objectives This study aimed to comparison of tuberculin skin test and T-SPOT.TB test in patients with receiving corticosteroid or immunosuppressive treatments.
Methods 38 patients were documented before introducing cytotoxic or anti-TNF therapies between November 2012 and November 2014. Results of T-SPOT.TB test and TST and current medication were enrolled. TST values > or =5 mm was accepted as TST positivity. According to use of corticosteroid the patients were divided into two groups. The patients receiving 20 mg methylprednisolon for three days before TST were included in Group I. The remaining patients were included in Group II.
Results In Group II TST were anergy in 6/14, negative in 1/14, positive in 7/14 patients. In Group I TST were anergy in 21/24, positive in 3/24 patients. When compared with Group II the numbers of anergic patient was higher while result of positive TST was lower in Group I (both for p<0.001). The T-SPOT.TB test results were similar between both groups. 7 patients with methotrexate and 2 patients with azathioprine were being treated. In this study, there were no effects of methotrexate or azathioprine on TST or T-SPOT.TB test.
Conclusions This study demonstrated that TST is evidently affected by corticosteroid treatment in a dose- and time-dependent manner. Therefore, it seems that T-SPOT.TB test is more appropriate for LTBI diagnosis in patients with treated corticosteroid.
Disclosure of Interest None declared