Diagnosing latent tuberculosis in immunocompromised patients measuring blood IP-10 production capacity: an analysis of chronic renal failure patients.

OBJECTIVE: Patients undergoing haemodialysis for chronic renal failure-hemodialysis (CRF-HD) are at risk of latent tuberculosis infection (LTBI). The effectiveness of using blood IP-10 production capacity to diagnose LTBI in CRF-HD patients was analysed.

METHODS: The study enrolled 50 CRF-HD patients. Interferon-γ release assay (IGRA) was done using QuantiFERON-TB Gold In Tube (QFG-IT) system. Blood IP-10 production capacity was measured using the QFG-IT system tubes. Tuberculin skin testing (TST) was performed on the same day and the test results were compared.

RESULTS: TST turned out to be positive in 36.4% of the patients and QFG-IT in 54% of them. After stimulation with specific tuberculosis antigens, blood IP-10 levels increased noticeably. The antigen-stimulated blood IP-10 level was significantly higher in patients who were either TST or QFG-IT positive than in patients whose tests were negative (p=0.0001). Using 4.02 pg/mL as the threshold for stimulated blood log-transformed IP-10 level, good agreement was observed between IP-10 and QFG-IT results (κ=1).

CONCLUSION: Blood IP-10 level, which can be measured simply, provides results equivalent to IGRAs for the diagnosis of LTBI in CRF-HD patients.