Population-level impact of same-day microscopy and Xpert MTB/RIF for tuberculosis diagnosis in Africa.
OBJECTIVE
To compare the population-level impact of two World Health Organization-endorsed strategies for improving the diagnosis of tuberculosis (TB): same-day microscopy and Xpert MTB/RIF (Cepheid, USA).


METHODS
We created a compartmental transmission model of TB in a representative African community, fit to the regional incidence and mortality of TB and HIV. We compared the population-level reduction in TB burden over ten years achievable with implementation over two years of same-day microscopy, Xpert MTB/RIF testing, and the combination of both approaches.


RESULTS
Same-day microscopy averted an estimated 11.0% of TB incidence over ten years (95% uncertainty range, UR: 3.3%-22.5%), and prevented 11.8% of all TB deaths (95% UR: 7.7%-27.1%). Scaling up Xpert MTB/RIF to all centralized laboratories to achieve 75% population coverage had similar impact on incidence (9.3% reduction, 95% UR: 1.9%-21.5%) and greater effect on mortality (23.8% reduction, 95% UR: 8.6%-33.4%). Combining the two strategies (i.e., same-day microscopy plus Xpert MTB/RIF) generated synergistic effects: an 18.7% reduction in incidence (95% UR: 5.6%-39.2%) and 33.1% reduction in TB mortality (95% UR: 18.1%-50.2%). By the end of year ten, combining same-day microscopy and Xpert MTB/RIF could reduce annual TB mortality by 44% relative to the current standard of care.


CONCLUSIONS
Scaling up novel diagnostic tests for TB and optimizing existing ones are complementary strategies that, when combined, may have substantial impact on TB epidemics in Africa.
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
David W
DW
Dowdy
J Lucian
JL
Davis
Saskia
S
den Boon
Nicholas D
ND
Walter
Achilles
A
Katamba
Adithya
A
Cattamanchi
D000349:Africa; D003955:Diagnostic Tests, Routine / Q000379:methods; D006801:Humans; D015994:Incidence; D008853:Microscopy; D009026:Mortality; D009169:Mycobacterium tuberculosis; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D059039:Standard of Care; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology
D011933:Reagent Kits, Diagnostic