Format

Send to

Choose Destination
Sci Rep. 2016 Jul 29;6:30781. doi: 10.1038/srep30781.

Serial testing for latent tuberculosis using QuantiFERON-TB Gold In-Tube: A Markov model.

Author information

1
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA.
2
Department of Medicine, UCSF, San Francisco, USA.
3
Tuberculosis and Hepatitis Programme, FIND, Geneva, Switzerland.
4
Department of Medicine, Stanford University, Palo Alto, USA.
5
Evidence Team, KNCV, The Hague, Netherlands.
6
Department of Epidemiology &Biostatistics and McGill International TB Centre, McGill University, Montreal, Canada.

Abstract

Healthcare workers (HCWs) in low-incidence settings are often serially tested for latent TB infection (LTBI) with the QuantiFERON-TB Gold In-Tube (QFT) assay, which exhibits frequent conversions and reversions. The clinical impact of such variability on serial testing remains unknown. We used a microsimulation Markov model that accounts for major sources of variability to project diagnostic outcomes in a simulated North American HCW cohort. Serial testing using a single QFT with the recommended conversion cutoff (IFN-g > 0.35 IU/mL) resulted in 24.6% (95% uncertainty range, UR: 23.8-25.5) of the entire population testing false-positive over ten years. Raising the cutoff to >1.0 IU/mL or confirming initial positive results with a (presumed independent) second test reduced this false-positive percentage to 2.3% (95%UR: 2.0-2.6%) or 4.1% (95%UR: 3.7-4.5%), but also reduced the proportion of true incident infections detected within the first year of infection from 76.5% (95%UR: 66.3-84.6%) to 54.8% (95%UR: 44.6-64.5%) or 61.5% (95%UR: 51.6-70.9%), respectively. Serial QFT testing of HCWs in North America may result in tremendous over-diagnosis and over-treatment of LTBI, with nearly thirty false-positives for every true infection diagnosed. Using higher cutoffs for conversion or confirmatory tests (for initial positives) can mitigate these effects, but will also diagnose fewer true infections.

PMID:
27469388
PMCID:
PMC4965809
DOI:
10.1038/srep30781
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Nature Publishing Group Icon for PubMed Central
Loading ...
Support Center