Background: Given the current lack of effective vaccines against TB, the accuracy of screening tests for determining or excluding latent TB infection (LTBI) is decisive in effective TB control. This meta-analysis critically appraises studies investigating the positive and the negative predictive value (PPV and NPV, respectively) from a test-determined LTBI state for progression to active TB of interferon-γ release assays (IGRAs) and the tuberculin skin test (TST).
Methods: We searched MEDLINE, EMBASE, and Cochrane bibliographies for relevant articles. After qualitative evaluation, the PPV and NPV for progression of commercial and “in-house” IGRAs and the TST for persons not receiving preventive treatment in the context of the respective IGRA studies were pooled using both a fixed and a random-effect model. Weighted rates were calculated for all study populations and for groups solely at high risk of TB development.
Results: The pooled PPV for progression for all studies using commercial IGRAs was 2.7% (95% CI, 2.3%-3.2%) compared with 1.5% (95% CI, 1.2%-1.7%) for the TST (P < .0001). PPV increased to 6.8% (95% CI, 5.6%-8.3%) and 2.4% (95% CI, 1.9%-2.9%) for the IGRAs and the TST, respectively, when only high-risk groups were considered (P < .0001). Pooled values of NPV for progression for both IGRAs and the TST were very high, at 99.7% (95% CI, 99.5%-99.8%) and 99.4% (95% CI, 99.2%-99.5%), respectively, although they were significantly higher for IGRAs (P < .01).
Conclusions: Commercial IGRAs have a higher PPV and NPV for progression to active TB compared with those of the TST, especially when performed in high-risk persons.