Background
Published 31 Oct 2020
Chest x-ray analysis with deep learning-based software as a triage test for pulmonary tuberculosis – a prospective study of diagnostic accuracy for culture-confirmed disease
Author: Faiz Ahmad Khan, Arman Majidulla, Gamuchirai Tavaziva , Ahsana Nazish, Syed Kumail Abidi, Andrea Benedetti, Dick Menzies, James C Johnston, Aamir Javed Khan, Saima Saeed1
Back
Deep learning-based radiological image analysis could facilitate use of chest x-rays as triage tests for pulmonary tuberculosis in resource-limited settings. We sought to determine whether commercially available chest x-ray analysis software meet WHO recommendations for minimal sensitivity and specificity as pulmonary tuberculosis triage tests.
Methods
We recruited symptomatic adults at the Indus Hospital, Karachi, Pakistan. We compared two software, qXR version 2.0 (qXRv2) and CAD4TB version 6.0 (CAD4TBv6), with a reference of mycobacterial culture of two sputa. We assessed qXRv2 using its manufacturer prespecified threshold score for chest x-ray classification as tuberculosis present versus not present. For CAD4TBv6, we used a data-derived threshold, because it does not have a prespecified one. We tested for non-inferiority to preset WHO recommendations (0·90 for sensitivity, 0·70 for specificity) using a non-inferiority limit of 0·05. We identified factors associated with accuracy by stratification and logistic regression.
Findings
We included 2198 (92·7%) of 2370 enrolled participants. 2187 (99·5%) of 2198 were HIV-negative, and 272 (12·4%) had culture-confirmed pulmonary tuberculosis. For both software, accuracy was non-inferior to WHO-recommended minimum values (qXRv2 sensitivity 0·93 [95% CI 0·89–0·95], non-inferiority p=0·0002; CAD4TBv6 sensitivity 0·93 [95% CI 0·90–0·96], p<0·0001; qXRv2 specificity 0·75 [95% CI 0·73–0·77], p<0·0001; CAD4TBv6 specificity 0·69 [95% CI 0·67–0·71], p=0·0003). Sensitivity was lower in smear-negative pulmonary tuberculosis for both software, and in women for CAD4TBv6. Specificity was lower in men and in those with previous tuberculosis, and reduced with increasing age and decreasing body mass index. Smoking and diabetes did not affect accuracy.
Interpretation
In an HIV-negative population, these software met WHO-recommended minimal accuracy for pulmonary tuberculosis triage tests. Sensitivity will be lower when smear-negative pulmonary tuberculosis is more prevalent.
Authors
Faiz Ahmad Khan, Arman Majidulla, Gamuchirai Tavaziva , Ahsana Nazish, Syed Kumail Abidi, Andrea Benedetti, Dick Menzies, James C Johnston, Aamir Javed Khan, Saima Saeed1
Citation
1. McGill International TB Centre 2. Research Institute of the McGill University Health Centre and McGill University Montreal 3. QC 4. Canada 5. Respiratory Epidemiology and Clinical Research Unit 6. Centre for Outcomes Research and Evaluation 7. Research Institute of the McGill University Health Centre 8. Montreal 9. QC 10. Canada 11. Department of Medicine and Department of Epidemiology 12. McGill University 13. Montreal 14. Canada 15. Interactive Research and Development Pakistan 16. Karachi 17. Pakistan 18. The Indus Hospital 19. Karachi 20. Pakistan 21. Ghori TB Clinic 22. University of British Columbia 23. Vancouver 24. BC 25. Canada 26. Interactive Research and Development Global 27. Singapore 28. Global Health Directorate 29. Indus Health Network 30. Karachi 31. Pakistan
