Format

Send to

Choose Destination
BMC Infect Dis. 2019 Feb 8;19(1):131. doi: 10.1186/s12879-019-3745-5.

Predictors of discordant latent tuberculosis infection test results amongst South African health care workers.

Author information

1
Division of Occupational Medicine, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
2
Department of Environmental and Occupational Studies, Faculty of Applied Sciences, Cape Peninsula University of Technology, Cape Town, South Africa.
3
Division of Clinical Epidemiology, McGill University Health Centre - Research Institute, Montreal, Canada.
4
Centre for Lung Infection and Immunity, Department of Medicine and UCT Lung Institute, University of Cape Town, Groote Schuur Hospital Observatory, H46.41 Old Main Building, Cape Town, 7925, South Africa. Keertan.dheda@uct.ac.za.

Abstract

BACKGROUND:

The tuberculin skin test (TST) and interferon-gamma-release-assays (IGRAs) are utilized in screening programmes for presumed latent tuberculosis infection (LTBI) in health care workers (HCWs). However, inter-test comparison yields high rates of discordance, which is poorly understood. The aim of the study was therefore to identify factors associated with discordance amongst HCWs in a TB and HIV endemic setting.

METHODS:

505 HCWs were screened for LTBI in South Africa using the TST and two IGRA assays (QuantiFERON-TB-Gold-In-Tube (QFT-GIT) and TSPOT.TB). Factors associated with discordance were analyzed using a multinomial logistic regression model.

RESULTS:

TST-IGRA discordance was negatively associated with longer duration of employment for both TSPOT.TB (OR = 0.92; 95% confidence interval (CI) 0.85-0.99) and QFT-GIT (OR = 0.90; 95% CI 0.84-0.96). Marked test discordance occurred in HIV-infected individuals who were more likely to have TSPOT.TB + ve / TST-ve discordance (OR 4.44; 95% CI 1.14-17.27) or TSPOT.TB + ve / QFT-GIT-ve test discordance (OR 5.72; 95% CI 1.95-16.78). Those engaged in home care were less likely to have QFT-GIT + ve/TSPOT.TB -ve / discordance (OR 0.32; 95% CI 0.10-0.95).

CONCLUSION:

The marked TST-IGRA and IGRA-IGRA discordance in HIV-infected individuals suggest greater sensitivity of TSPOT.TB in immunocompromised persons or potential greater reactivity of TSPOT.TB in this population.

KEYWORDS:

Discordance and health care worker; Latent tuberculosis infection; Sensitivity; Specificity

PMID:
30736743
PMCID:
PMC6368796
DOI:
10.1186/s12879-019-3745-5
Free full text

Supplemental Content

Full text links

Icon for BioMed Central
Loading ...
Support Center