Earlier this month, APVS staff visited the two sites in Africa where TBDx™ technology is currently installed and operational. In addition to performing system checks and maintenance, this was an opportunity to interact with the key stakeholders, to observe the operational workflow of TBDx™ in the Center for Tuberculosis, and to assess the ongoing technology evaluation in Abuja.
Center for Tuberculosis / National Institute of Infectious Diseases, South Africa
TBDx™ continues to perform an important role in the mass screening protocol aimed at reducing the significant backlog of stained sputum slides prepared as part of the Drug Resistance Survey at the NICD/CTB lab in Johannesburg. Excitement and enthusiasm remains high with respect to TBDx™ due to its high volume, auto-loading slide processing capability, and its ability to provide consistently high detection performance.
Dr. Nazir Ismail, CTB Director, and his colleague from the London School of Tropical Medicine, Dr. James Lewis, have completed the final draft version of the TBDx™ publication of the study results from 2013. The final draft will be submitted to the remaining 7 co-authors for final review and comment. The working title of the paper is, “Performance of an automated microscopy system as a diagnostic and triaging tool to Xpert MTB/Rif for the diagnosis of Tuberculosis.” The paper presents clear scientific evidence demonstrating how the performance of TBDx™, when combined with Xpert MTB/Rif, can be used as a triage or screening tool to achieve high sensitivity, high specificity, and lower by 80% the potential cost of Xpert usage. The intent is to submit the paper to the American Journal of Respiratory and Critical Care Medicine (AJRCCM).
Zankli Medical Center, Abuja, Nigeria
The extensive TBDx™ evaluation, which features multiple molecular tests in combination with using TBDx for screening or triage, is nearing completion. While patient studies were initially slow in developing, the usage of TBDx™ has increased significantly over the past month due to unanticipated patient backlog. During the week, APVS staff witnessed the evaluation of several hundred cases, bringing to around 1,200 the total number of slides processed so far. The evaluation goal is to examine 1,500 cases.
TBDx™ operator enthusiasm remains very high as the system allows the TB laboratory staff to perform additional duties while TBDx™ processes slides.
Both new and familiar observations were made during the visit:
- Success in the TBDx™ digital image system remains dependent on consistently well-prepared slides. This provides the necessary basis for proper image focus and evaluation. As such, TBDx™ will reject slides missing necessary quality control.
- Directly prepared slides, sputum directly applied as a smear rather than concentrated using a centrifuge, can be harder to read, but TBDx™ has maintained consistent levels of performance. It tells us that performance may be the same for both slide preparation techniques, and this could have a favorable budget impact on laboratories.
- An uninterrupted power supply remains essential and in some countries the system may require a battery back-up supply.
Executive-level discussions were held with key members of Zankli Medical Center, TB Reach and the Nigerian office of the Center for Disease Control (CDC) on several fronts:
- Evidence is mounting that the feasibility of automated sputum microscopy, represented in TBDx™, could become a recommended alternative to routine microscopy and a very beneficial diagnostic screening tool and quality control option.
- The next step is to assess operational performance and determine necessary daily laboratory workflow changes to best accommodate TBDx™.
- Each executive in the discussion acknowledged that operational studies will be vital to securing WHO review and endorsement.
- With the intent of recommending the TBDx™ technology for nationwide deployment within Nigeria, there is interest in evaluating TBDx™ in Maraba, an environment with high levels of disease and poverty. It is likely this next stage would begin soon after completion of the current study.
- There is considerable enthusiasm for completing the study and getting the results published.
The 45th Union World Conference on Lung Disease
The study team in Nigeria, consisting of Prof. Luis Cuevas, Prof. Lovett Lawson, and Dr. Olanrewaju Oladimeji, et.al, submitted an abstract containing interim results of the TBDx™ evaluation. The abstract has been accepted for presentation to the conference attendees in Barcelona, Spain on October 31, 2014.
New Diagnostics Working Group
Each year the Stop TB Partnership / New Diagnostic Working Group hold its annual meeting prior to the start of the Union Conference. Among the information sessions presented is a panel discussion on the latest diagnostic technology research results. From recent discussions it is likely that Prof. Luis Cuevas, of the Liverpool School of Tropical Medicine and one of the primary study investigators for the TBDx™ evaluation in Nigeria, will be reporting the interim results to the audience.
With the completion of the Nigerian TB Reach study, and combined with the South African DRS study, we will have moved one step closer to WHO endorsement. Further, these large-scale and statistically relevant studies will have proven the efficacy of the technology in two unique settings. Through our relationship with FIND we will add two additional studies, Peru and Vietnam, which will demonstrate the performance of TBDx™ across varied geographic areas. The staff will be leaving for Peru in late August. The evaluation will take place in Lima, at the Tropical Medicine Institute of the Cayetano Heredia University.
These efforts have generated a vast volume of scientific evidence on the performance of TBDx™. This evidence has further introduced our technology to a wide-ranging international audience, creating such attention that TBDx™ and automated sputum microscopy are increasingly acknowledged as a viable TB detection alternative. We will sustain our efforts to reach and educate as many knowledge leaders in the TB community as possible, as we continue to create momentum and interest.