title: Automated chest-radiography as a triage for Xpert testing in resource-constrained settings: a prospective study of diagnostic accuracy and costs.
abstract: 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.
authors.affiliation: Diagnostic Image Analysis Group, Radboud university medical center, Department of Radiology and Nuclear Medicine Internal postal code 766, 6500 HB Nijmegen, The Netherlands.
authors.forename: R H H M
authors.initials: RH
authors.lastname: Philipsen
authors.affiliation: Diagnostic Image Analysis Group, Radboud university medical center, Department of Radiology and Nuclear Medicine Internal postal code 766, 6500 HB Nijmegen, The Netherlands.
authors.forename: C I
authors.initials: CI
authors.lastname: Sánchez
authors.affiliation: Diagnostic Image Analysis Group, Radboud university medical center, Department of Radiology and Nuclear Medicine Internal postal code 766, 6500 HB Nijmegen, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Maduskar
authors.affiliation: Diagnostic Image Analysis Group, Radboud university medical center, Department of Radiology and Nuclear Medicine Internal postal code 766, 6500 HB Nijmegen, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Melendez
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud university medical center, Department of Radiology, Internal postal code 766 6500 HB Nijmegen, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Peters-Bax
authors.affiliation: Lung Infection and Immunity Unit and Centre for Tuberculosis Research Innovation, Division of Pulmonology, Department of Medicine, University of Cape Town Lung Institute Cape Town, South Africa.
authors.forename: J G
authors.initials: JG
authors.lastname: Peter
authors.affiliation: Lung Infection and Immunity Unit and Centre for Tuberculosis Research Innovation, Division of Pulmonology, Department of Medicine, University of Cape Town Lung Institute Cape Town, South Africa.
authors.forename: R
authors.initials: R
authors.lastname: Dawson
authors.affiliation: Lung Infection and Immunity Unit and Centre for Tuberculosis Research Innovation, Division of Pulmonology, Department of Medicine, University of Cape Town Lung Institute Cape Town, South Africa.
authors.forename: G
authors.initials: G
authors.lastname: Theron
authors.affiliation: Lung Infection and Immunity Unit and Centre for Tuberculosis Research Innovation, Division of Pulmonology, Department of Medicine, University of Cape Town Lung Institute Cape Town, South Africa.
authors.forename: K
authors.initials: K
authors.lastname: Dheda
authors.affiliation: Diagnostic Image Analysis Group, Radboud university medical center, Department of Radiology and Nuclear Medicine Internal postal code 766, 6500 HB Nijmegen, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: van Ginneken
mesh_terms: D000328:Adult; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D000069550:Machine Learning / Q000191:economics / Q000706:statistics & numerical data; D008297:Male; D025202:Molecular Diagnostic Techniques / Q000191:economics; D009426:Netherlands / Q000453:epidemiology; D010363:Pattern Recognition, Automated / Q000191:economics* / Q000379:methods; D015995:Prevalence; D011446:Prospective Studies; D013902:Radiography, Thoracic / Q000191:economics* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D040841:Resource Allocation / Q000191:economics; D012680:Sensitivity and Specificity; D014218:Triage / Q000191:economics* / Q000706:statistics & numerical data; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000191:economics* / Q000453:epidemiology; D014600:Utilization Review