Comparing Mycobacterium tuberculosis RNA Accuracy in Various Respiratory Specimens for the Rapid Diagnosis of Pulmonary Tuberculosis

Abstract

Objective

To evaluate the rapid diagnostic accuracy of Mycobacterium tuberculosis RNA (TB-RNA) for pulmonary tuberculosis (PTB) in a large patient sample and to evaluate the difference in TB-RNA diagnostic accuracy in various respiratory specimens.

Methods

Patient medical records were retrospectively reviewed to determine the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of the acid-fast bacillus (AFB) smear and TB-RNA to evaluate their diagnostic accuracy against final clinical diagnosis.

Results

Of the 2336 patients ultimately included, 1123 provided 1 sputum specimen each and 1213 provided 1 bronchoalveolar lavage fluid (BALF) specimen each. The overall sensitivity, specificity, PPV, NPV, and AUC of the AFB smear were 36.2%, 86.4%, 90.6%, 27.3%, and 0.61, respectively. The overall sensitivity, specificity, PPV, NPV, and AUC of TB-RNA for the rapid detection of PTB were 57.4%, 99.4%, 99.7%, 39.3%, and 0.78, respectively. When sputum and BALF specimens were used for AFB smear testing, the sensitivity, specificity, PPV, NPV, and AUC of the AFB smear were 44.5%, 81.5%, 87.5%, 33.5%, and 0.63; and 29.2%, 92.7%, 94.8%, 22.5%, and 0.61, respectively. The sensitivity, specificity, PPV, NPV, and AUC of TB-RNA for the rapid detection of PTB using sputum were 49.6%, 99.3%, 99.5%, 40.4%, and 0.74, respectively; whereas those of TB-RNA determined using BALF were 63.9%, 99.5%, 99.8%, 38.0%, and 0.82, respectively.

Conclusion

The diagnostic accuracy of TB-RNA for PTB was moderate and considerably better than that of the AFB smear. The diagnostic accuracy of TB-RNA for various respiratory specimens differed; the diagnostic accuracy of TB-RNA for BALF specimens was substantially better than that for sputum samples, and BALF specimens were more suitable for TB-RNA.

Keywords:

• tuberculosis RNA
• pulmonary tuberculosis
• bronchoalveolar lavage fluid
• sputum
• accuracy

Data Sharing Statement

Data will be made available on reasonable request from corresponding authors.

Ethics Approval and Consent to Participate

All patients gave written informed consent and the study was approved by the Human Research Ethics Committee of Affiliated Hangzhou Chest Hospital, Zhejiang University School of Medicine. This study complies with the Declaration of Helsinki.

Acknowledgments

We are grateful to all the patients and their families included in this study and also to our colleagues in this unit for their help.

Disclosure

The authors declare that they have no conflicts of interest in relation to this work.

Additional information

Funding

Xiaowei Qiu, 20191203B133, Hangzhou Science and Technology Bureau, http://kj.hangzhou.gov.cn. The founders did not have a role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.