Dynamic changes in positive interferon-gamma release assay in a dialysis population: An observational cohort study.
BACKGROUND
Interferon-gamma release assay (IGRA) is popular for detecting latent tuberculosis infection (LTBI), but its dynamic change is uncertain in high-risk groups such as dialysis patients.


METHODS
Patients undergoing dialysis were prospectively enrolled. The QuantiFERON-TB Gold In-Tube (QFT-GIT) was used to detect LTBI. After 6 and 12 months, QFT-GIT was repeated to monitor dynamic changes.


RESULTS
Only 204 of 391 enrolled patients completed the study. The initial QFT-GIT positive rate of 22.1% decreased to 19.6% after 6 months and to 14.2% after 12 months. The 6-month reversion rate was 45.9% while the conversion rate was 7.7%. Sub-population with new QFT-GIT positivity had 87.5% reversion rate, higher than the 20.8% of patients with persistent QFT-GIT positivity. The QFT-GIT response was independently associated with persistent QFT-GIT positivity. Using 0.93 IU/ml of the initial QFT-GIT response as the threshold can detect 79% persistent positivity in 6-month follow-up. Prior TB had a borderline significance for predicting conversion.


CONCLUSIONS
In the dialysis population, reversion and conversion occur frequently within six months. The QFT-GIT positive population is heterogeneous and sub-populations have different reversion rates. Higher QFT-GIT positivity threshold can identify patients with persistent QFT-GIT positivity to prioritize follow-up and LTBI therapy.
Department of Traumatology, National Taiwan University Hospital, Taipei City, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
Chin-Chung
CC
Shu
Vin-Cent
VC
Wu
Feng-Jung
FJ
Yang
Chia-Lin
CL
Hsu
Sung-Ching
SC
Pan
Jann-Yuan
JY
Wang
Jann-Tay
JT
Wang
Chong-Jen
CJ
Yu
Li-Na
LN
Lee
D000368:Aged; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000276:immunology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D006435:Renal Dialysis / Q000379:methods*
Conversion; Dialysis; Interferon-gamma release assay; Latent tuberculosis infection; Reversion