Interferon-gamma release assays for the diagnosis of extrapulmonary tuberculosis: a systematic review and meta-analysis

Abstract

Interferon -gamma release assays (IGRAs) provide a new diagnostic method for Mycobacterium tuberculosis (TB) infection. However, the diagnostic value of IGRAs for extrapulmonary TB (EPTB) has not been clarified. We searched several databases and selected papers with strict inclusion criteria, evaluated the evidence of commercially available IGRAs (QuantiFERON(®) -TB Gold QFT-G or QFT-GIT and T-SPOT(®) .TB) on blood and the tuberculin skin test (TST) using random effects models. Twenty studies with 1711 patients were included. After excluding indeterminate results, pooled sensitivity for the diagnosis of EPTB was 72% [95% confidence interval (CI) 65-79%] for QFT-G or GIT and 90% (95% CI, 86-93%) for T-SPOT; in high-income countries the sensitivity of QFT-G or GIT (79%, 95% CI 72-86%) was much higher than that (29%, 95% CI 14-48%) in low/middle-income countries. Pooled specificity for EPTB was 82% (95% CI 78-87%) for QFT-G or GIT and 68% (95% CI 64-73%) for T-SPOT. Pooled sensitivity of TST from four studies in high-income countries was lower than that of IGRAs. T-SPOT was more sensitive in detecting EPTB than QFT-G or GIT and TST. However, both IGRAs and TST have similar specificity for EPTB. IGRAs have limited value as diagnostic tools to screen and rule out EPTB, especially in low/middle-income countries. The immune status of patients does not affect the diagnostic accuracy of IGRAs for EPTB.

Utility of QuantiFERON-TB Gold In-Tube Test in the Diagnosis of Latent TB in HIV-Positive Patients in a Medium-TB Burden Country

“…[20][21][22] Such results happen when the nil tube shows strong reaction or when reaction is weak in mitogen and TB antigen tubes. Some reasons for indeterminate results include inappropriate sampling and incubation, presensitization of T cells with an unknown antigen, and immune suppression.…”

Gamma Interferon Release Assays for Detection of Mycobacterium tuberculosis Infection

“…Three systematic reviews have assessed the ability of IGRAs to diagnose active TB in adults, including extrapulmonary TB, with consistent conclusions that active TB can neither be ruled in nor ruled out with IGRAs (7,8,50). Because IGRAs (like the TST) have suboptimal sensitivity for active TB, especially in HIV-infected persons, a negative result cannot reliably rule out active TB.…”

“…Fan and colleagues summarized the performance of IGRAs for extrapulmonary TB diagnosis and found that both IGRAs and the TST had poor specificity in distinguishing extrapulmonary TB from LTBI, especially in low-income countries (50).…”

Abdominal lymphangioma mimicking peritoneal tuberculosis

“…IGRA is specific for Mycobacterium tuberculosis infection although it cannot determine active or latent infection. IGRA has 72% sensitivity in diagnosing extra-pulmonary TB 6 . BCG vaccination does not interfere with the results of IGRA 7 .…”