Abstract:

Objective: Assessing the accuracy of automated EasyNAT system for rapidly detecting paraffin-embedded tissue for the diagnosis of tuberculosis. Methods: A retrospective analysis was conducted on 134 patients, comprising 101 with confirmed tuberculosis and 33 without tuberculosis, treated at Beijing Chest Hospital, Capital Medical University, between 2018 and 2022.The clinical diagnostic results served as the standard for assessing the diagnostic performance of the EasyNAT system in comparison to quantitative real-time polymerase chain reaction (qPCR) for tuberculosis detection in paraffin-embedded tissues.The evaluation criteria included sensitivity, specificity, positive predictive value, negative predictive value, and accuracy rate. Results: Based on the clinical diagnostic results, the EasyNAT assay demonstrated a sensitivity of 87.1%(88/101, 95%CI: 79.2%-92.3%)and a specificity of 100.0%(33/33, 95%CI: 89.6%-100.0%).The positive predictive value, negative predictive value, and accuracy rate were 100% (88/88, 95%CI: 95.8%-100.0%), 71.7%(33/46, 95%CI: 57.5%-82.7%), and 90.3%(121/134, 95%CI: 84.1%-94.2%), respectively.In comparison, the qPCR assay exhibited a sensitivity of 96.0%(90.3%-98.5%)and a specificity of 100.0%(89.6%-100.0%).The positive predictive value, negative predictive value, and accuracy rate for qPCR were 100.0%(96.2%-100.0%), 89.2%(75.3%- 95.7%), and 97.0%(92.6%-98.8%).The Cohen's kappa value of 0.84 indicated substantial agreement between EasyNAT and qPCR.The detection rate of tuberculosis using this method was 86.4%(38/44, 95%CI: 73.3%-93.6%), while the detection rate for extrapulmonary tuberculosis was 87.7%(50/57, 95%CI: 76.8%-93.9%).In comparison, qPCR showed a detection rate of 97.7%(88.2%- 99.6%) for pulmonary tuberculosis and 94.7%(85.6%-98.6%)for extrapulmonary tuberculosis.There was no statistically significant difference in the detection results between the method and qPCR for both pulmonary and extrapulmonary tuberculosis(P>0.05).Importantly, the EasyNAT detection combined nucleic acid extraction, amplification, and analysis into one process.Compared with traditional qPCR methods, manual operation time was reduced by 2 hours, leading to an overall reduction in total testing time by 3 hours. Conclusion: The EasyNAT nucleic acid rapid detection system can quickly, conveniently, and accurately detect Mycobacterium tuberculosis DNA in paraffin-embedded tissues, demonstrating significant clinical utility in the pathological diagnosis of tuberculosis.

Key words: Tuberculosis, Diagnosis, Paraffin-embedded tissue, Molecular pathology, Cross-priming isothermal amplification technology