Serial QuantiFERON-TB Gold In-Tube assay and tuberculin skin test to
diagnose latent tuberculosis in household Mexican contacts: conversion and reversion
rates and associated factors using conventional and borderline zone
definitions |
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Authors: | Joel Monárrez-Espino José Antonio Enciso-Moreno Lucie Laflamme Carmen J Serrano |
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Institution: | 1. Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden;2. Medical Research Unit Zacatecas, Mexican Institute of Social Security, Zacatecas, Mexico |
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Abstract: | A cohort of 123 adult contacts was followed for 18‐24 months (86 completed the
follow-up) to compare conversion and reversion rates based on two serial measures of
QuantiFERON (QFT) and tuberculin skin test (TST) (PPD from TUBERSOL, Aventis Pasteur,
Canada) for diagnosing latent tuberculosis (TB) in household contacts of TB patients
using conventional (C) and borderline zone (BZ) definitions. Questionnaires were used
to obtain information regarding TB exposure, TB risk factors and socio-demographic
data. QFT (IU/mL) conversion was defined as <0.35 to ≥0.35 (C) or <0.35 to
>0.70 (BZ) and reversion was defined as ≥0.35 to <0.35 (C) or ≥0.35 to <0.20
(BZ); TST (mm) conversion was defined as <5 to ≥5 (C) or <5 to >10 (BZ) and
reversion was defined as ≥5 to <5 (C). The QFT conversion and reversion rates were
10.5% and 7% with C and 8.1% and 4.7% with the BZ definitions, respectively. The TST
rates were higher compared with QFT, especially with the C definitions (conversion
23.3%, reversion 9.3%). The QFT conversion and reversion rates were higher for TST
≥5; for TST, both rates were lower for QFT <0.35. No risk factors were associated
with the probability of converting or reverting. The inconsistency and apparent
randomness of serial testing is confusing and adds to the limitations of these tests
and definitions to follow-up close TB contacts. |
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Keywords: | close contact QuantiFERON latent TB Mexico serial testing |
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