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International Journal of Rheumatology
Volume 2012, Article ID 381929, 8 pages
Clinical Study

Immunosuppression Adversely Affects TST but Not IGRAs in Patients with Psoriasis or Inflammatory Musculoskeletal Diseases

1Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, P.O. Box 21, 00014 Helsinki, Finland
2Eastern Finland Laboratory Centre Joint Authority Enterprise (ISLAB), Mikkeli District Laboratory, Porrassalmenkatu 35-37, FI-50100 Mikkeli, Finland
3Division of Infectious Diseases, Department of Medicine, Helsinki University Central Hospital, P.O. Box 348, FI-00029 HUS, Helsinki, Finland
4Institute of Clinical Medicine, University of Helsinki, P.O. Box 20, 00014 Helsingin Yliopisto, Finland
5Department of Internal Diseases, Länsi-Uusimaa Hospital, P.O. Box 1020, Itäinen rantakatu 9, 10601 Tammisaari, Finland
6Department of Dermatology and Allergology, Helsinki University Central Hospital, P.O. Box 160, HUS 00029, Helsinki, Finland
7Division of Clinical Microbiology, Helsinki University Central Hospital, HUSLAB, P.O. Box 400, HUS 00029, Helsinki, Finland
8Division of Rheumatology, Department of Medicine, Helsinki University Central Hospital, P.O. Box 440, HUS 00029, Helsinki, Finland

Received 19 October 2011; Revised 6 March 2012; Accepted 13 March 2012

Academic Editor: Lazaros I. Sakkas

Copyright © 2012 Esko Tavast et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The performance of the interferon gamma release assays (IGRAs) and tuberculin skin test (TST) was reviewed retrospectively in patients with psoriasis, inflammatory musculoskeletal diseases, or miscellaneous inflammatory conditions. The study was carried out over a 22-month period using 109 records of patients with psoriasis ( 𝑛 = 2 1 ), musculoskeletal disease ( 𝑛 = 7 4 ), or other inflammatory conditions ( 𝑛 = 1 4 ). Forty-four (48%) of 109 patients were on immunosuppressive therapy and 38/109 (35%) on systemic glucocorticoid therapy. The agreement between the IGRAs was substantial ( 𝜅 = 0 . 7 1 ) whilst that between the IGRAs and TST was low ( 𝜅 = 0 . 3 2 ). Logistic regression models revealed that IGRAs associated with risk factors for latent tuberculosis infection better than TST. TST was influenced by age, BCG vaccination, sex, and glucocorticoid therapy. We found that IGRAs performed equally well with low level of indeterminate results (1-2%). IGRAs were superior to TST because the latter was influenced by BCG-vaccination status and immunosuppressive therapy.