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Poor agreement between diagnostic tests for latent tuberculosis infection among HIV‐infected persons in Hong Kong
Author(s) -
Leung Chi Chiu,
Chan Kenny,
Yam Wing Cheong,
Lee Man Po,
Chan Chi Kuen,
Wong Ka Hing,
Ho Pak Leung,
Mak Ida,
Tam Cheuk Ming
Publication year - 2016
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1111/resp.12805
Subject(s) - medicine , tuberculosis , tuberculin , latent tuberculosis , viral load , human immunodeficiency virus (hiv) , mycobacterium tuberculosis , immunology , pathology
Background and objective The tuberculin skin test (TST), T‐Spot.TB (T‐Spot) and QuantiFERON‐TB Gold‐In Tube (QFT) were compared in diagnosing latent tuberculosis infection (LTBI) among human immunodeficiency virus (HIV)‐infected persons. Methods Human immunodeficiency virus‐infected persons without previous history of tuberculosis or LTBI were simultaneously tested by TST, T‐Spot and QFT annually and followed up for tuberculosis. Results Among 110 HIV‐infected subjects with 85% previous TST screening coverage, 75% on anti‐retroviral therapy, well‐preserved median CD4 count (414/μL) and low median viral load (<75/μL), baseline TST, T‐Spot and QFT were positive in 5.5%, 5.6% and 4.9%, respectively, with almost complete discordance of positive results. Among 91 (83%), 66 (60%) and 26 (24%) subjects successfully undergoing the first, second and third annual retesting, TST, T‐Spot and QFT were, respectively, positive in 11/123 (8.9%), 13/173 (7.5%) and 21/182 (11.5%) on retesting, with similar discordance of positive results. There was no significant association with the concurrent CD4 count or viral load. Conversion occurred in 11/123 (8.9%), 8/160 (5.0%) and 18/168 (10.7%) of TST, T‐Spot and QFT, respectively, and none was associated with changes in CD4 count or viral load. More than half of the positive T‐SPOT and QFT results reverted to negative on follow‐up. None of these tests picked up the single case of culture‐confirmed tuberculosis observed after 798 person‐years of follow‐up. Conclusion Major discordance in positive results, high reversion rates and low tuberculosis incidence among test‐positive subjects cast serious doubt on the utility of the currently available LTBI tests in the annual screening of HIV‐infected persons in an intermediate tuberculosis burden area.