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Int J Tuberc Lung Dis. 2017 Jun 1;21(6):690-696. doi: 10.5588/ijtld.16.0764.

The sensitivity of the QuantiFERON®-TB Gold Plus assay in Zambian adults with active tuberculosis.

Author information

1
School of Social and Community Medicine, University of Bristol, Bristol, UK.
2
Zambart, Ridgeway Campus, Lusaka, Zambia.
3
Zambart, Ridgeway Campus, Lusaka, Zambia, Faculty of Infectious and Tropical Diseases.
4
Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK.

Abstract

SETTING AND OBJECTIVE:

To investigate the sensitivity of the new interferon-gamma release assay (IGRA), QuantiFERON®-TB Gold Plus (QFT-Plus), for active TB (used as a surrogate for latent tuberculous infection) in a Zambian TB clinic.

DESIGN:

Consecutive smear or Xpert® MTB/RIF-positive adult (age 18 years) pulmonary TB patients were recruited between June 2015 and March 2016. Venous blood was tested using QFT-Plus. The sensitivity was defined as the number positive divided by the total number tested. Using logistic regression, factors associated with positive QFT-Plus results were explored.

RESULTS:

Of 108 patients (median age 32 years, interquartile range 27-38; 73% male; 63% human immunodeficiency virus [HIV] positive), 90 were QFT-Plus-positive, 11 were negative and seven had indeterminate results; sensitivity was 83% (95%CI 75-90). There was no difference in sensitivity by HIV status (HIV-positive 85%, 95%CI 75-93; n = 68 vs. HIV-negative 80%, 95%CI 64-91; n = 40; P = 0.59). In models adjusted for age alone, CD4 cell count <100 cells/μl (OR 0.15, 95%CI 0.02-0.96; P = 0.05) and body mass index <18.5 kg/m2 (OR 0.27, 95%CI 0.08-0.91; P = 0.02) were associated with decreased odds of positive QFT-Plus results.

CONCLUSION:

Overall, the sensitivity of QFT-Plus is similar to that of the tuberculin skin test and other IGRAs. While overall sensitivity is not affected by HIV status, QFT-Plus sensitivity was lower among people living with HIV/acquired immune-deficiency syndrome with severe immunosuppression.

PMID:
28482964
PMCID:
PMC5424670
DOI:
10.5588/ijtld.16.0764
[Indexed for MEDLINE]
Free PMC Article

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