title: 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.
authors.affiliation: Tuberculosis Center for Diagnosis and Treatment, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Fan
authors.forename: Zhou
authors.initials: Z
authors.lastname: Chen
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Hao
authors.forename: Zhong-Yi
authors.initials: ZY
authors.lastname: Hu
authors.forename: He-Ping
authors.initials: HP
authors.lastname: Xiao
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D016206:Databases, Bibliographic; D019049:Developed Countries; D003906:Developing Countries; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis*; D059425:Interferon-gamma Release Tests / Q000191:economics / Q000706:statistics & numerical data*; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000191:economics / Q000706:statistics & numerical data; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology; D055815:Young Adult
chemical_list: D007371:Interferon-gamma