Automated chest-radiography as a triage for Xpert testing in resource-constrained settings: a prospective study of diagnostic accuracy and costs

• Published in: Scientific reports Vol. 5; no. 1; p. 12215
• Main Authors: Philipsen, R. H. H. M., Sánchez, C. I., Maduskar, P., Melendez, J., Peters-Bax, L., Peter, J. G., Dawson, R., Theron, G., Dheda, K., van Ginneken, B.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27.07.2015; Nature Publishing Group
• Subjects: 49/47; 639/705/794; 692/699/255/1856; 692/700/1421/1770; 692/700/1538; Adult; Automation; Chest; Female; Health Care Costs - statistics & numerical data; Health policy; Humanities and Social Sciences; Humans; Machine Learning - economics; Machine Learning - statistics & numerical data; Male; Molecular Diagnostic Techniques - economics; multidisciplinary; Netherlands - epidemiology; Pattern Recognition, Automated - economics; Pattern Recognition, Automated - methods; Prevalence; Prospective Studies; Public health; Radiography; Radiography, Thoracic - economics; Radiography, Thoracic - statistics & numerical data; Reproducibility of Results; Resource Allocation - economics; Science; Sensitivity and Specificity; Sputum; Triage - economics; Triage - statistics & numerical data; Tuberculosis; Tuberculosis, Pulmonary - diagnosis; Tuberculosis, Pulmonary - economics; Tuberculosis, Pulmonary - epidemiology; Utilization Review; Netherlands
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep12215

Molecular tests hold great potential for tuberculosis (TB) diagnosis, but are costly, time consuming and HIV-infected patients are often sputum scarce. Therefore, alternative approaches are needed. We evaluated automated digital chest radiography (ACR) as a rapid and cheap pre-screen test prior to Xpert MTB/RIF (Xpert). 388 suspected TB subjects underwent chest radiography, Xpert and sputum culture testing. Radiographs were analysed by computer software (CAD4TB) and specialist readers and abnormality scores were allocated. A triage algorithm was simulated in which subjects with a score above a threshold underwent Xpert. We computed sensitivity, specificity, cost per screened subject (CSS), cost per notified TB case (CNTBC) and throughput for different diagnostic thresholds. 18.3% of subjects had culture positive TB. For Xpert alone, sensitivity was 78.9%, specificity 98.1%, CSS $13.09 and CNTBC $90.70. In a pre-screening setting where 40% of subjects would undergo Xpert, CSS decreased to $6.72 and CNTBC to $54.34, with eight TB cases missed and throughput increased from 45 to 113 patients/day. Specialists, on average, read 57% of radiographs as abnormal, reducing CSS ($8.95) and CNTBC ($64.84). ACR pre-screening could substantially reduce costs and increase daily throughput with few TB cases missed. These data inform public health policy in resource-constrained settings.