Performance of IGRAs for TB Infection Diagnosis in Elderly

Background: Diagnosis and screening for latent tuberculosis in old patients is of special interest in regards of the morbidity-mortality of this disease in that context.

TB-infection diagnosis based on immunological memory detection can be impaired with age. New blood tests (QFTB-G and T-SPOT.TB) specific for MTB infection have not been evaluated in those old patients.The primary endpoint of this study is the evaluation of the IGRAS for active TB diagnosis in patients above 75 years old.

In vitro Interferon Gamma releasing Assay (IGRA) are recommended for LTBI screening as or instead of TST, but there accuracy in those old patients are not known: as immune responses are impaired in elderly and some of them have already met M tuberculosis before active antibiotherapy exists.The aim of this study is to evaluate characteristics of the two commercials tests IGRA T-spot-TB® and Quantiferon-TB-gold- in tube® and TST in old patients with or without active Tuberculosis.

Principal outcome:

\- 3 tests performance for active TB diagnosis in patients older than 75 years-old

Secondary outcomes :

* concordance between IGRAs. * non-concordant results analysis * concordance of IGRAs results with time of TB-infection * biobank

Methodology :Diagnostic test performance study