Background: Indeterminate results are a recognised limitation of interferon-γ release assays (IGRA) in the diagnosis of latent tuberculosis (TB) infection (LTBI) and TB disease, especially in children. We investigated whether age and common co-morbidities were associated with IGRA performance in an unselected cohort of resettled refugees. Methods: A retrospective cross-sectional study of refugees presenting for their post-resettlement health assessment during 2006 and 2007. Refugees were investigated for prevalent infectious diseases, including TB, and for common nutritional deficiencies and haematological abnormalities as part of standard clinical screening protocols. Tuberculosis screening was performed by IGRA; QuantiFERON-TB Gold in 2006 and QuantiFERON-TBGold In-Tube in 2007. Results: Complete data were available on 1130 refugees, of whom 573 (51%) were children less than 17 years and 1041 (92%) were from sub-Saharan Africa. All individuals were HIV negative. A definitive IGRA result was obtained in 1004 (89%) refugees, 264 (26%) of which were positive; 256 (97%) had LTBI and 8 (3%) had TB disease. An indeterminate IGRA result was obtained in 126 (11%) refugees (all failed positive mitogen control). In multivariate analysis, younger age (linear OR = 0.93 [95% CI 0.91-0.95], P<0.001), iron deficiency anaemia (2.69 [1.51-4.80], P = 0.001), malaria infection (3.04 [1.51-6.09], P = 0.002), and helminth infection (2.26 [1.48-3.46], P<0.001), but not vitamin D deficiency or insufficiency, were associated with an indeterminate IGRA result. Conclusions: Younger age and a number of common co-morbidities are significantly and independently associated with indeterminate IGRA results in resettled predominantly African refugees. © 2012 Banfield et al.

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Africa south of the Sahara refugee Australia mass screening methodology iron deficiency anemia metabolism human clinical assessment Communicable Diseases Refugees comorbidity statistics Cohort Studies interferon gamma release assay Interferon-gamma Release Tests Malaria Logistic Models screening test ethnology Cross-Sectional Studies cross-sectional study Humans anemia Adolescent male iron deficiency latent tuberculosis female preschool child tuberculosis Child, Preschool summer Western Australia seasonal variation vitamin D deficiency Article Retrospective Studies communicable disease adult major clinical study schistosomiasis age Age Factors age distribution cohort analysis statistical model retrospective study Child