Background/Purpose:  
Interferon-ƴ
release assays (IGRAs) offer the possibility of an improved method to detect TB
infections in pts with autoimmune disorders.  Compare results of an IGRA vs standard
TST as a screening tool for latent TB infection (LTBI) in the Golimumab [GLM] PURSUIT
Ulcerative Colitis (UC) program versus GLM SC Rheumatology (RA, PsA, AS) program¹.

Methods: In both programs, pts were screened
for LTBI using standard TST and IGRA to assess eligibility in the following studies:
PURSUIT-SC and PURSUIT-IV; GO-BEFORE, GO-FORWARD, GO-AFTER, GO-REVEAL, and
GO-RAISE, resp. Any pt with a newly identified positive finding for TB in whom
there was no evidence of active TB was permitted to enter provided appropriate
treatment for LTBI was initiated before or at the time of first dose of drug. TST
was performed by the Mantoux method, using 5TUs of PPD standard or 2TU of PPD
RT-23. TST was deemed positive for LTBI according to local country guidelines
for an immunosuppressed host or, in the absence of local guidelines, according
to an induration ≥5mm. The IGRA used to screen for LTBI was
QuantiFERON-TB Gold In-Tube test. Overall IGRA and TST results were assessed.  Prior
BCG vaccination and con meds(ie corticosteroids and/or immunomodulators) on
outcome was also assessed.

Results:
 In GLM PURSUIT,
1283 pts and in GLM Rheumatology 2282 pts had both IGRA and TST screening prior
to GLM treatment.  Both programs were global; differences were PURSUIT included
S. Africa and the Rheum program included Asia.  In the PURSUIT and Rheum
programs, agreement between the TST and IGRA results, measured by the kappa
coefficient, was 0.135 (95% CI, 0.050-0.220; p=0.028) and 0.22 (95% CI,
0.157-0.279; p=0.021), resp.  Overall, in PURSUIT, 501(39.0%) of 1283 pts had
previously received BCG vaccine; among this vaccinated group, the rate of
positivity for LTBI by TST was 10.4%  vs 5.0% for IGRA positivity.  In the
Rheum program, 781 (34.2%) of 2282 pts had previously received BCG vaccine;
within this vaccinated group, the rate of positivity for LTBI by TST was 15.2%
vs 9.1% for IGRA positivity.  PURSUIT pts who had not received the BCG vaccine,
the rate of positivity by TST was 1.9% vs 2.8 % for IGRA positivity compared
with 5.0% vs 5.8%, resp, in the Rheum program. When IGRA was repeated in PURSUIT
pts whose results were initially indeterminate, the majority of pts(67.0%) were
IGRA negative on repeat whereas the number of pts whose results were positive
was 5.3%; IGRA remained indeterminate for 27.7%. Similar results were seen in
the Rheum program (74% IGRA negative, 2.7% positive, and 23.2% remained
indeterminate).  Concomitant corticosteroid and/or immunomodulator use did not
appear to have an impact on results.

Conclusion:   Results of this comparison
suggest IGRA provides greater specificity and possibly greater sensitivity than
TST, and performs similarly in UC and Rheum populations.  

¹Hsia EC et al. A & R Vol. 64,
No 7, July 2012 pp 2068-2077