Interferon-γ release assays vs. tuberculin skin test for the screening of latent tuberculosis infection: an overview of systematic reviews

Article type
Authors
Chen Q1, Li Y1, Yang X2
1Chinese Cochrane Center, West China Hospital, Sichuan University, China
2West China Hospital, Sichuan University, China
Abstract
Background: It is estimated that two billion people suffered from latent tuberculosis infection (LTBI). Due to the significance of LTBI for TB prevention, it is critical to evaluate the accuracy of tests for LTBI. The interferon-γ -release assays (IGRAs) has potential advantages over tuberculin test (TST), but evidence varied.

Objectives: To summarize the effectiveness of IGRAs for diagnosing (or screening) LTBI, based on the patient-important outcomes.

Methods: Database of Medline, Embase, Biosis, Cochrane Central Register of Controlled Trials, etc, were searched, using keyword of ‘LTBI’, IGRA, ‘systematic review’, etc, till June 2011. Two reviewers independently performed data extraction.

Results: Seven studies were included. Outcomes were ranked according to a hierarchy of reference standards for the performance of IGRAs for diagnosing (or screening) LTBI. efficiency of preventive therapy based on IGRAs results: no SR reported this outcome. The predicitive value of IGRAs for ATB: two SRs reported the cases of ATB occurred among IGRA+were more than those among TST+. Correlation of TB exposure gradient: three SR reported the correlation of TB exposure gradient and IGRA results were much influenced than TST, with P = 0.03 reported in one SR, while the other SRs reported positive correlation. Sen: the included SR reported that the Sen of IGRA in high and low burden TB countries were above 67% and 78% respectively. Spn: Three SRs reported that the Spn were above 90%, more than the TST Spn of BCG vaccines (50%). The concordance with TST: moderate concordance between IGRAs and TST were showed in three SRs, with the range of kappa values being (0.03–0.87), (0.4–0.6), (0.05–0.56), respectively.

Conclusions: IGRA have modrate concordance with TST, but with higher specificity, without influence of BCG. High-quality studies targeted the therapy effectiveness of TB preventive based on IGRA results should conduct to provide the patient-important evidence. This study was funded by the Sichuan Provincial Government’s Science & Technology Program (2010SZ0078) and the National Natural Science Foundation of China (81102206).