TY - JOUR
T1 - "Proof-Of-Concept" Evaluation of an Automated Sputum Smear Microscopy System for Tuberculosis Diagnosis
AU - Lewis, James J.
AU - Chihota, Violet N.
AU - van der Meulen, Minty
AU - Fourie, P. Bernard
AU - Fielding, Katherine L.
AU - Grant, Alison D.
AU - Dorman, Susan E.
AU - Churchyard, Gavin J.
N1 - Funding Information:
We thank the participants who consented to take part in this study. We also thank the many stakeholders for their support for the study to be implemented, particularly: the National Union of Mineworkers, Solidarity and United Unions of South Africa; AngloGold Ashanti, Gold Fields and Harmony mining companies; the South African Chamber of Mines; the Mine Health and Safety Council; and the South African government Departments of Mineral Resources, Health and Labour. We thank the large study team for their commitment and persistent efforts to ensure that the study was successfully implemented, as well as Gerrit Coetzee for his support and assistance with this study. We gratefully acknowledge funding from: the Consortium to Respond Effectively to the AIDS TB Epidemic, United States, who received funding from the Bill and Melinda Gates foundation; the South African Mine Health and Safety Council; the Foundation for Innovative New Diagnostics, Switzerland; National Institutes of Health/National Institutes of Allergy and Infectious Diseases award #AI077486; UK Department of Health (Public Health Career Scientist award to AG); NIH Fogarty ICORTA TB/AIDS (grants 5U2RTW007370 and 5U2RTW007373 to VC).
PY - 2012/11/29
Y1 - 2012/11/29
N2 - Background: "TBDx" is an innovative smear microscopy system that automatically loads slides onto a microscope, focuses and digitally captures images and then classifies smears as positive or negative using computerised algorithms. Objectives: To determine the diagnostic accuracy of TBDx, using culture as the gold standard, and compare this to a microscopist's diagnostic performance. Methods: This study is nested within a cross-sectional study of tuberculosis suspects from South African gold mines. All tuberculosis suspects had one sputum sample collected, which was decontaminated prior to smear microscopy, liquid culture and organism identification. All slides were auramine-stained and then read by both a research microscopist and by TBDx using fluorescence microscopes, classifying slides based on the WHO classification standard of 100 fields of view (FoV) at 400× magnification. Results: Of 981 specimens, 269 were culture positive for Mycobacterium tuberculosis (27.4%). TBDx had higher sensitivity than the microscopist (75.8% versus 52.8%, respectively), but markedly lower specificity (43.5% versus 98.6%, respectively). TBDx classified 520/981 smears (53.0%) as scanty positive. Hence, a proposed hybrid software/human approach that combined TBDx examination of all smears with microscopist re-examination of TBDx scanty smears was explored by replacing the "positive" result of slides with 1-9 AFB detected on TBDx with the microscopist's original reading. Compared to using the microscopist's original results for all 981 slides, this hybrid approach resulted in equivalent specificity, a slight reduction in sensitivity from 52.8% to 49.4% (difference of 3.3%; 95% confidence interval: 0.2%, 6.5%), and a reduction in the number of slides to be read by the microscopist by 47.0%. Discussion: Compared to a research microscopist, the hybrid software/human approach had similar specificity and positive predictive value, but sensitivity requires further improvement. Automated microscopy has the potential to substantially reduce the number of slides read by microscopists.
AB - Background: "TBDx" is an innovative smear microscopy system that automatically loads slides onto a microscope, focuses and digitally captures images and then classifies smears as positive or negative using computerised algorithms. Objectives: To determine the diagnostic accuracy of TBDx, using culture as the gold standard, and compare this to a microscopist's diagnostic performance. Methods: This study is nested within a cross-sectional study of tuberculosis suspects from South African gold mines. All tuberculosis suspects had one sputum sample collected, which was decontaminated prior to smear microscopy, liquid culture and organism identification. All slides were auramine-stained and then read by both a research microscopist and by TBDx using fluorescence microscopes, classifying slides based on the WHO classification standard of 100 fields of view (FoV) at 400× magnification. Results: Of 981 specimens, 269 were culture positive for Mycobacterium tuberculosis (27.4%). TBDx had higher sensitivity than the microscopist (75.8% versus 52.8%, respectively), but markedly lower specificity (43.5% versus 98.6%, respectively). TBDx classified 520/981 smears (53.0%) as scanty positive. Hence, a proposed hybrid software/human approach that combined TBDx examination of all smears with microscopist re-examination of TBDx scanty smears was explored by replacing the "positive" result of slides with 1-9 AFB detected on TBDx with the microscopist's original reading. Compared to using the microscopist's original results for all 981 slides, this hybrid approach resulted in equivalent specificity, a slight reduction in sensitivity from 52.8% to 49.4% (difference of 3.3%; 95% confidence interval: 0.2%, 6.5%), and a reduction in the number of slides to be read by the microscopist by 47.0%. Discussion: Compared to a research microscopist, the hybrid software/human approach had similar specificity and positive predictive value, but sensitivity requires further improvement. Automated microscopy has the potential to substantially reduce the number of slides read by microscopists.
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U2 - 10.1371/journal.pone.0050173
DO - 10.1371/journal.pone.0050173
M3 - Article
C2 - 23209666
AN - SCOPUS:84870523873
SN - 1932-6203
VL - 7
JO - PloS one
JF - PloS one
IS - 11
M1 - e50173
ER -