Cumulative False-Positive QuantiFERON-TB Interferon-γ Release Assay Results

Area of Science:

• Medical Diagnostics
• Infectious Disease Research
• Public Health Screening

Background:

• The QuantiFERON-TB (interferon-gamma release assay) is increasingly used for latent tuberculosis screening despite concerns about reliability.
• Evidence regarding its reproducibility and accuracy in serial testing is needed.

Purpose of the Study:

• To evaluate the reproducibility of the QuantiFERON-TB assay in annual screening.
• To assess the accumulation of false-positive results with repeated annual testing.
• To examine the validity of confirming positive results with a second QuantiFERON-TB test.

Main Methods:

• Retrospective, longitudinal evaluation of serial screening results from 2001 to 2013.
• Review of QuantiFERON-TB and tuberculin test results in a cohort of emergency responders.
• Analysis of test results over a maximum of 7 years of annual examinations.

Main Results:

• Positive QuantiFERON-TB results occurred sporadically in new individuals each year.
• Only 10 of 80 initially positive individuals remained positive the following year; 9 became negative within 3 years.
• After 7 years, 27.4% of the cohort had a positive result, indicating cumulative, irreproducible positives.

Conclusions:

• Frequent, cumulative, sporadic, and irreproducible positive results were observed.
• Findings support discontinuing the QuantiFERON-TB assay for latent tuberculosis diagnosis in low-risk populations.
• The assay's performance in serial screening raises significant concerns about its diagnostic utility.