A-285 Performance Evaluation of LIAISON® QuantiFERON®-TB Gold Plus Assay and Its Use in Long-Term Care Facilities

Abstract

Abstract Background Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis with 7860 cases reported in 2021 in the United State and estimated 13 million people are living with Latent TB infection (LTBI); Early detection of TB infection is crucial to prevent the spread of the disease; there are two types of tests for TB and LTBI: Tuberculin Skin Test (TST) and Interferon-Gamma Release Assay (IGRA). Although TST has good sensitivity but false-negative reactions occur in certain population and the specificity of is decreased among persons with prior Bacillus Calmette-Guérin (BCG) vaccination, especially those vaccinated post-infancy and those with repeat vaccination. Similarly, persons living in areas where nontuberculous mycobacteria are common are at increased risk of having false-positive TST reactions. IGRA is blood-based laboratory test that measures responses to TB-specific peptide antigens in whole blood. Like the tuberculin skin test (TST), it is an indirect test for M. tuberculosis infection, but is more specific than TST and is unaffected by prior BCG vaccination and most environmental mycobacterial infections. Methods The LIAISON® QuantiFERON®-TB Gold Plus assay is an in vitro diagnostic test for the detection of interferon-γ (IFN-γ) in human lithium heparin plasma by chemiluminescence immunoassay (CLIA) using the LIAISON ® XL Analyzer. The clinical specificity and sensitivity were 96.9% and 84.4% respectively. Clinical studies have shown Positive Percent Agreement (PPA) of 97.4% and Negative Percent Agreement (NPA) of 98.6%. We evaluated the precision, reproducibility, and correlated patient results to our reference lab results. 452 samples collected from Long-Term Care facilities resident were run over 9 months. Statistical analyses were done using Analyse-it. Results The percentage agreement for precision, reproducibility, and accuracy were 100%. The correlation with the reference laboratory was 100% agreement. We found 14.8% of samples tested were positive, 83.2% were negative and 2.0% were indeterminate. Conclusion The LIAISON® QuantiFERON®-TB Gold Plus assay offers the benefit of a fully automated with high sensitivity and specificity. The faster turnaround will aid the physician in the diagnosing M. tuberculosis, eliminates the need for two-step testing, and is preferred in patients who received BCG vaccination. In addition, with the growing geriatric population, the availability of this test will give the physician the opportunity to follow the 2016 American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA)/CDC clinical practice guidelines for using IGRAs in older patients.