Hoon Hee Lee1, Dong Hwan Choi2, Jeong-Ran Kim3, Young Gyun Kim4, Kyung-Wook Jo1, Tae Sun Shim5. 1. Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea. 2. R&D Center, Boditech Med Inc., Chuncheon, South Korea. 3. Department of Research and Development, The Korean Institute of Tuberculosis, Cheongju, South Korea. 4. AB Medical Inc., Jangseong, South Korea. 5. Division of Pulmonology and Critical Care Medicine, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea. shimts@amc.seoul.kr.
Abstract
INTRODUCTION: We compared the performance of a fluorescence lateral flow assay (ichroma™ IGRA-TB) with the QuantiFERON-TB Gold PLUS (QFT-PLUS) for the diagnosis of latent tuberculosis infection (LTBI) in patients with immune-mediated inflammatory diseases (IMID) prior to receiving biologics therapy. METHOD: The comparability of the ichroma™ IGRA-TB assay with the QFT-PLUS assay for the diagnosis of LTBI was determined in prospectively enrolled patients with IMID prior to receiving biologics between August 2018 and October 2019. To determine the best cut-off value of the ichroma™ IGRA-TB, an ROC curve analysis was performed. RESULTS: Patients with IMID (n = 145) had inflammatory bowel disease (n = 83; 57.2%), rheumatoid arthritis (n = 44; 30.3%), or spondyloarthropathy (n = 18; 12.4%). The median age was 40.5 (interquartile range: 27.0-56.0), 72 (49.7%) were men, and 140 (96.6%) received BCG vaccination. With the manufacturer-recommended cut-off values, 11 (7.6%) and 20 (13.8%) patients showed positive results with the ichroma™ IGRA-TB and QFT-PLUS tests, respectively. The overall agreement between the two tests was 91.0% with a Cohen's kappa value of 0.535 (95% confidence interval: 0.317-0.754). ROC curve analysis of the QFT-PLUS results showed that a cut-off value of > 0.21 IU/mL would improve the performance of the ichroma™ IGRA-TB. Using the new cut-off value, the concordance rate was improved to 93.1% with a Cohen's kappa value of 0.668 (95% confidence interval: 0.478-0.858). CONCLUSIONS: The ichroma™ IGRA-TB could be used as a point-of-care test for LTBI screening in IMID patients before starting biologics, especially in resource-limited settings. Key Points • The ichroma™ IGRA-TB is an automated fluorescence lateral flow assay-based IGRA. • The test has advantages like short turn-around time, low-cost, and ease of use. • The ichroma™ IGRA-TB showed high agreement with the QuantiFERON-TB Gold In-Tube in patients with chronic immune-mediated inflammatory diseases before starting biologics.
INTRODUCTION: We compared the performance of a fluorescence lateral flow assay (ichroma™ IGRA-TB) with the QuantiFERON-TB Gold PLUS (QFT-PLUS) for the diagnosis of latent tuberculosis infection (LTBI) in patients with immune-mediated inflammatory diseases (IMID) prior to receiving biologics therapy. METHOD: The comparability of the ichroma™ IGRA-TB assay with the QFT-PLUS assay for the diagnosis of LTBI was determined in prospectively enrolled patients with IMID prior to receiving biologics between August 2018 and October 2019. To determine the best cut-off value of the ichroma™ IGRA-TB, an ROC curve analysis was performed. RESULTS:Patients with IMID (n = 145) had inflammatory bowel disease (n = 83; 57.2%), rheumatoid arthritis (n = 44; 30.3%), or spondyloarthropathy (n = 18; 12.4%). The median age was 40.5 (interquartile range: 27.0-56.0), 72 (49.7%) were men, and 140 (96.6%) received BCG vaccination. With the manufacturer-recommended cut-off values, 11 (7.6%) and 20 (13.8%) patients showed positive results with the ichroma™ IGRA-TB and QFT-PLUS tests, respectively. The overall agreement between the two tests was 91.0% with a Cohen's kappa value of 0.535 (95% confidence interval: 0.317-0.754). ROC curve analysis of the QFT-PLUS results showed that a cut-off value of > 0.21 IU/mL would improve the performance of the ichroma™ IGRA-TB. Using the new cut-off value, the concordance rate was improved to 93.1% with a Cohen's kappa value of 0.668 (95% confidence interval: 0.478-0.858). CONCLUSIONS: The ichroma™ IGRA-TB could be used as a point-of-care test for LTBI screening in IMID patients before starting biologics, especially in resource-limited settings. Key Points • The ichroma™ IGRA-TB is an automated fluorescence lateral flow assay-based IGRA. • The test has advantages like short turn-around time, low-cost, and ease of use. • The ichroma™ IGRA-TB showed high agreement with the QuantiFERON-TB Gold In-Tube in patients with chronic immune-mediated inflammatory diseases before starting biologics.
Authors: Elitza S Theel; Heather Hilgart; Margaret Breen-Lyles; Kevin McCoy; Rhiannon Flury; Laura E Breeher; John Wilson; Irene G Sia; Jennifer A Whitaker; Jeremy Clain; Timothy R Aksamit; Patricio Escalante Journal: J Clin Microbiol Date: 2018-06-25 Impact factor: 5.948