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Published on: March 24, 2017
Validation of a model for predicting smear-positive active pulmonary tuberculosis in patients with initial acid-fast
Jun -Jun Yeh1,2,3,4,5
1Department of Chest Medicine, Section of Thoracic Imaging, Ditmanson Medical Foundation Chia-Yi Christian Hospital, No. 539, Zhongxiao Rd., Chiayi City, 600, Taiwan. anvin.funlan@msa.hinet.net.
Objectives:
The objective of this study was to develop a predictive model for final smear-positive (SP) active pulmonary tuberculosis (aPTB) in patients with initial negative acid fast bacilli (AFB) sputum smears (iSN-SP-aPTB) based on high-resolution computed tomography (HRCT).
Method And Materials:
Eighty (126, 21) patients of iSN-SP-aPTB and 402 (459, 876) patients of non-initial positive acid fast bacilli (non-iSP) pulmonary disease without iSN-SP-aPTB were included in a derivation (validation, prospective) cohort. HRCT characteristics were analysed, and multivariable regression and receiver operating characteristic (ROC) curve analysis was performed to develop a score predictive of iSN-SP-aPTB.
Results:
The derivation cohort showed clusters of nodules/mass of the right upper lobe or left upper lobe were independent predictors of iSN-SP-aPTB, while bronchiectasis in the right middle lobe or left lingual lobe were negatively associated with iSN-SP-aPTB. A predictive score for iSN-SP-aPTB based on these findings was tested in the validation and prospective cohorts. With an ideal cut-off score = 1, the sensitivity, specificity, positive predictive value, and negative predictive value of the prediction model were 87.5% (90%, 90.5%), 99% (97.1%, 98.4%), 94.6% (81.3%, 57.5%), and 97.6% (97%, 99.8%) in the derivation (validation, prospective) cohorts, respectively.
Conclusions:
The model may help identify iSN-SP-aPTB among patients with non-iSP pulmonary diseases.
Key Points:
• Smear-positive active pulmonary tuberculosis that is initial smear-negative (iSN-SP-aPTB) is infectious. • High-resolution computed tomography can identify iSN-SP-aPTB among non-iSP pulmonary diseases. • Clusters nodules/mass in right/left upper lobe are positively associated with iSN-SP-aPTB. • Bronchiectasis in right middle/left lingual lobe is negatively associated with iSN-SP-aPTB. • The model may have high post-test probability in identifying iSN-SP-aPTB.
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