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Implementation of in-house Xpert MTB/RIF Ultra testing reduces diagnostic turnaround time and modeled airborne isolation costs

Published online by Cambridge University Press:  27 October 2026

Amin Ektesabi
Affiliation:
University of Toronto , Canada
Jennifer Tat
Affiliation:
Vancouver Coastal Health Research Institute, Vancouver, Canada
Matthew P. Muller
Affiliation:
Unity Health Toronto, Toronto, Canada Department of Medicine, University of Toronto, Toronto, Canada
Yan Chen
Affiliation:
Unity Health Toronto, Toronto, Canada
Larissa M. Matukas*
Affiliation:
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
*
Corresponding author: Larissa M. Matukas; Email: larissa.matukas@utoronto.ca

Abstract

Content of image described in text.

Objective:

To evaluate the operational and economic impact of in-house Xpert MTB/RIF Ultra (Ultra) testing for suspected pulmonary tuberculosis (TB) in a low-incidence acute care setting.

Design:

Prospective implementation study with diagnostic performance assessment and modeled airborne-isolation cost analysis.

Setting:

Toronto hospital network comprising two acute care hospitals and an outpatient TB clinic.

Participants:

Adults evaluated for suspected pulmonary TB.

Methods:

Sputum specimens underwent in-house Ultra testing and reference-laboratory acid-fast bacilli (AFB) smear microscopy and culture. Diagnostic performance was assessed against culture using single-sputum and two-sputum strategies with exact 95% confidence intervals (CIs). Isolation costs were modeled using paired turnaround-time differences and probabilistic sensitivity analysis.

Results:

Among 164 specimens from 108 patients, median turnaround time was 7 hours for Ultra versus 81 hours for smear (P < .0001); the mean paired reduction was 58.3 hours (SD, 32.2). Compared to mycobacterial culture, single-sputum sensitivity was 73.3% (95% CI, 44.9%–92.2%) for Ultra and 62.5% (24.5%–91.5%) for smear; specificity was 97.8% (92.4%–99.7%) and 92.0% (84.8%–96.5%), respectively. Two-sputum sensitivity was 100.0% for Ultra (3/3; 95% CI, 29.2%–100.0%) and smear (2/2; 15.8%–100.0%); specificity was 100.0% (88.4%–100.0%) and 96.8% (83.3%–99.9%), respectively. Mean modeled savings were CAD $1,277 per patient; 98.7% of simulations favored Ultra.

Conclusions:

In-house Ultra shortened diagnostic turnaround time and was associated with lower modeled isolation costs, supporting further evaluation of Ultra-informed isolation protocols. Ultra showed favorable diagnostic performance estimates, although results were imprecise.

Information

Type
Original Article
Creative Commons
Creative Common License - CCCreative Common License - BYCreative Common License - NCCreative Common License - ND
This is an Open Access article, distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives licence (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided that no alterations are made and the original article is properly cited. The written permission of Cambridge University Press or the rights holder(s) must be obtained prior to any commercial use and/or adaptation of the article.
Copyright
© The Author(s), 2026. Published by Cambridge University Press on behalf of The Society for Healthcare Epidemiology of America
Figure 0

Table 1. Diagnostic performance of AFB smear microscopy and Xpert MTB/RIF Ultra by sputum testing strategyTable 1 long description.

Figure 1

Table 2. Study cohort and diagnostic-result summaryTable 2 long description.

Figure 2

Table 3. Summary of Xpert MTB/RIF Ultra and mycobacterial culture resultsTable 3 long description.

Figure 3

Figure 1. Comparison of diagnostic turnaround times between Xpert MTB/RIF Ultra and AFB smear microscopy. A Distribution of turnaround times from specimen receipt to result reporting for Xpert MTB/RIF Ultra and AFB smear microscopy. Violin plots illustrate the distribution of observed turnaround times, with significantly shorter reporting times observed for Ultra (p < 0.0001). B Distribution of paired turnaround time differences (ΔT = AFB - Ultra). Positive values represent time saved using the Ultra diagnostic pathway. Dashed lines represent mean and median values. C Cumulative proportion of reported results over time for each diagnostic workflow. The x-axis is shown in 24-hour intervals, with each interval corresponding to one day. Ultra results accumulate rapidly within the first operational day, whereas smear microscopy reporting occurs more gradually over several days.

Figure 4

Figure 2. Modeled economic impact of reduced diagnostic turnaround time with in-house Ultra testing. A Modeled per-patient cost difference as a function of daily airborne isolation cost. The central line represents the mean modeled cost difference, while the shaded region represents uncertainty across simulated turnaround time estimates. B Distribution of simulated incremental per-patient cost differences generated through Monte Carlo simulation. The dashed vertical line indicates the threshold between cost increase and cost savings. The mean modeled benefit was CAD $1,277 per patient, with 98.7% of simulations demonstrating a net cost advantage associated with the Ultra diagnostic pathway. The left-sided tail in panel B reflects simulations in which smaller turnaround-time differences and/or higher Ultra pathway costs reduced the magnitude of savings.Figure 2 long description.

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