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Lancet delivers key details on a rapid new Ebola test; quantifies sensitivity/specificity and explores study limitations

**Embargo: 00:01 [UK time] Friday 26 June, 2015**

 

A new test can accurately predict within minutes if an individual has Ebola Virus Disease (EVD), according to new research published in The Lancet. The study is the first to show that a point-of-care EVD test (ReEBOV Antigen Rapid Test; Corgenix) is faster than and as sensitive as a conventional laboratory-based molecular method used for clinical testing during the recent outbreak in Sierra Leone.

 

This new rapid diagnostic test (RDT) could cut back on the lengthy process usually required to confirm if a patient has EVD, help identify case contacts, and ultimately curb the spread of Ebola.

 

Currently, diagnosis of EVD requires a full vial of venous blood to be shipped to a laboratory with a high level of biosafety and staff expertise for testing by real-time reverse transcription polymerase chain reaction (RT-PCR). This method poses substantial risks to the healthcare workers responsible for blood collection, transport, and testing, and efforts to contain the Ebola epidemic in west Africa have been hampered by this slow and complex diagnostic test.

 

“Laboratory results can sometimes take days to return. Delays like this result not only in the failure to diagnose and treat Ebola-infected patients, but also in individuals without Ebola being admitted to holding units where they may be subsequently infected with the virus,” [1] explains Dr Nira Pollock, senior author and Associate Medical Director of the Infectious Diseases Diagnostic Laboratory at the Boston Children’s Hospital, USA.

 

“This new test, on the other hand, is capable of detecting the Ebola virus in just a small drop of blood tested at the bedside, and could help us in the fight against Ebola.” [1]

 

In this study, the researchers compared the diagnostic accuracy of the new RDT against the benchmark RT-PCR test (altona Diagnostics) being used for clinical diagnosis in the field reference laboratory run by Public Health England at Port Loko in Sierra Leone.

 

106 suspected Ebola patients admitted to two treatment centres in Sierra Leone (run by the Ministry of Health and Sanitation of Sierra Leone and supported by the non-governmental organisation Partners In Health) during February 2015 were tested by both RDT (performed on a fingerstick blood sample at the point-of-care) and by standard RT-PCR (performed on plasma in the laboratory). Both RDT (on whole blood) and RT-PCR (on plasma) were also performed on 284 samples in the laboratory.

 

The RDT detected all confirmed cases of EVD that were positive by RT-PCR in both point-of-care (28/105 patients) and laboratory testing (45/277 patients), with sensitivity of 100% (identifying all patients with EVD as per the benchmark method), and a specificity of 92% (identifying patients who didn’t have EVD).

 

Surprisingly, the findings also revealed that the standard altona RT-PCR test, under the conditions deployed in the field, was itself an imperfect reference standard. The altona RT-PCR assay failed to detect a small number of EVD cases that tested positive by both RDT and by an alternative RT-PCR test (Trombley), all with relatively low amounts of virus. Both the RDT and altona assays failed to detect a small number of EVD cases that tested positive by the Trombley test, all with very low amounts of virus. The authors caution that given the limitations of the performance of the altona RT-PCR reference test in patients with low levels of the virus in their blood, more research is needed to assess how the new RDT will perform in patients very early in the course of EVD.

 

According to co-author Dr Jana Broadhurst from Partners In Health, Boston, USA, “This test could have an immediate impact on patient care and infection control by reliably detecting patients well into their illness who are likely to be highly infectious. Earlier test results would improve triage of patients, enabling staff to focus on those most likely to have Ebola, and reducing the opportunity for infection of non-Ebola ‘suspects’. Although the RDT requires refrigeration, this is already available in many health centres in endemic areas, particularly those that store vaccines and other medical products.” [1]

 

Writing in a linked Comment, Dr Nahid Bhadelia from Boston University School of Medicine and Boston Medical Center, Boston, USA says, “[This study] validates the accuracy of the ReEBOV RDT in patients who are well into their illness…suggesting it could be used to triage this subset of patients if RT-PCR is not available, particularly in those with a high index of clinical suspicion for a differential diagnosis…the data presented provide crucial information about the point of-care function of this rapid diagnostic test, such as ease of use, quality of samples taken at the bedside, and the concordance with venous samples…the results raise caution regarding the performance of the widely used altona RT-PCR assay, which the authors suggest might have underperformed because of laboratory specific technical and performance factors.”

NOTES TO EDITORS:

This study was funded by a gift from the Abundance Foundation (Stephen Kahn). Corgenix provided the test kits.

[1] Quotes direct from authors and cannot be found in text of Article.

 

For interviews with Article author Dr Nira Pollock, Partners In Health and Boston Children’s Hospital, Boston, USA please contact her directly on T) +1 857-218-5113 or 1-617-504-9294 (mobile) E) nira.pollock@childrens.harvard.edu

 

For interviews with Article author Dr Jana Broadhurst, Partners In Health, Boston, USA please contact her directly on T) +1 (541) 521-1698  E)janabroadhurst@gmail.com

 

For interviews with Article author Professor Megan Murray, Director of Research, Partners In Health, Boston, USA please contact her directly on T) +1 (617) 432-2781  E) megan.murray.epi@gmail.com

 

For interviews with Comment author Dr Nahid Bhadelia, Boston University School of Medicine and Boston Medical Center, Boston, USA please contact Jenny Eriksen Leary, Medical Relations Manager, Boston Medical Center T) +1 617-638-6841 E) jenny.eriksen@bmc.org

 

For full Article and Comment see: http://press.thelancet.com/EbolaTest.pdf

For Appendix see: http://press.thelancet.com/EbolaTestAppx.pdf

NOTE: THE ABOVE LINKS ARE FOR JOURNALISTS ONLY; IF YOU WISH TO PROVIDE A LINK TO THIS PAPER FOR YOUR READERS, PLEASE USE THE FOLLOWING, WHICH WILL GO LIVE AT THE TIME THE EMBARGO LIFTS: http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(15)61042-X/abstract

 

Caroline Brogan

Media Relations Assistant

The Lancet journals

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Phone: +44 (0) 20 7424 4249

Mobile: +44 (0) 7500 761363

Email: c.brogan@lancet.com

 

Rating

4 Star

New rapid diagnostic test for Ebola could be game changer in the fight against the disease

Our Review Summary

Biological sample testing of Ebola Virus

This release from the The Lancet plays up a first-of-its-kind rapid diagnostic test for Ebola virus disease (EVD). We’re told the ReEBOV Antigen Rapid Test (made by Corgenix) could be a powerful future tool in detecting, monitoring, and controlling outbreaks of EVD. The excitement stems from a recent field study conducted during an Ebola outbreak. After that trial, the release explains, clinicians found the test to be faster than and as reliable as the current standard method for detecting EVD, called real-time reverse transcription polymerase chain reaction (RT-PCR). The release helpfully quantifies both the sensitivity and specificity of the test, giving readers a thorough overview of the test’s performance both in identifying cases of Ebola and ruling it out in people who don’t have it. What’s more, the release tells us, the new rapid-diagnostic test requires just a drop of blood instead a vial of blood, and takes minutes to get a result instead of days.

The new test sounds like a potentially critical new tool in rapidly diagnosing EVD, but it has strings attached. The release does disclose these caveats — e.g. the test missed some early cases, it requires refrigeration, and it’s ability to detect EVD early on is limited. Our wish list for this otherwise very complete release includes context about how deadly EVD is and how it’s transmitted; what the symptoms are; what regions its endemic to; etc. We’d also like to know a bit about the regulatory side of things — which of these tests have been approved, and what are the roadblocks to approval/bringing the test to the field?

 

Why This Matters

On average, the Ebola virus kills about half of the people it infects. Recent outbreaks in Africa have claimed tens of thousands of lives. Although standard diagnostic tests take hours to process, it might take days for samples to reach a lab from remote places where an outbreak is happening. In addition, there have been reports in Guinea of potentially infected individuals not wanting to travel for testing due to a cultural mistrust of authority figures. So any fast and reliable diagnostic test — especially one requiring only a finger prick — could help workers on the ground detect and control the spread of an outbreak, as well as reduce the risk of infection to themselves (since Ebola virus spreads through bodily fluids).

Criteria

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

We don’t see any dollar signs in this release, either for the new test or RT-PCR. According to a New York Times blog post, they cost $60-$200 each.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Satisfactory

The release dedicates two paragraphs to describing the results, including comparing them to standard tests made by two different companies. We were particularly pleased to see reporting on the sensitivity and specificity of the test, as well as descriptions of what those numbers mean. We think those figures are important to include in any discussion of screening or diagnostic testing, but they’re often not provided or reported incompletely.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The release explains how not having a rapid-diagnostic test could expose people who are otherwise healthy to Ebola. But there are some less obvious harms this release probably should have addressed. For example, there’s only brief mention of how the new test missed some early cases of EVD. Waiting a few minutes for a result is better than hours or days, of course, but letting infected patients with a false-negative test out of quarantine is a serious concern. It would also be useful to talk about the impact of a false-positive result (since specificity was 92%). What are the consequences of telling someone they have Ebola when they don’t, in fact, have the infection?

Does the news release seem to grasp the quality of the evidence?

Satisfactory

The release runs through key statistics with the efficacy of the new test. It also discusses its shortcomings, attaches numbers to those, and discloses that further testing is required to better understand the limitations.

Does the news release commit disease-mongering?

Satisfactory

No excessively scary descriptions of Ebola virus infections are anywhere to be found. But because the release didn’t include any general information about EVD, it has an opposite problem — a journalist might not grasp the scope and urgency of controlling outbreaks, and how intimately a new test might play a role. For example, few understand that there continues to be widespread transmission that is poorly controlled in Guinea in particular. We’ll rate this Satisfactory with reservations.

Does the news release identify funding sources & disclose conflicts of interest?

Satisfactory

We’re told the Abundance Foundation funded the test and the maker of the rapid-diagnostic test, Corgenix, provided the kits.

Does the news release compare the new approach with existing alternatives?

Satisfactory

This is definitely a strong part of the release — the new test is compared to two manufacturers’ versions of the standard RT-PCR test. But the release doesn’t mention other diagnostic tests, including virus isolation and ELISA.

Does the news release establish the availability of the treatment/test/product/procedure?

Satisfactory

We’re told the following, via a quote from a researcher: “Although the RDT requires refrigeration, this is already available in many health centres in endemic areas, particularly those that store vaccines and other medical products.” Although we’d like to know more about the regulatory approval status of the test, we’ll award a Satisfactory here.

Does the news release establish the true novelty of the approach?

Satisfactory

The release does a fine job of establishing novelty: this new test takes minutes instead of what might take days; results can happen on-site; it only takes a few drops of blood from a finger instead of a vial’s worth by vein.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Satisfactory

There are a couple of points of contention here. The term “game-changer” used in the headline is rarely justified, but we think the release provides the evidence to show that this test could, in fact, be a game changer. In addition, we’re not sure that the test is “as sensitive as a conventional laboratory-based molecular method used for clinical testings.” In reality, it did as well as one manufacturer’s test in the field, but worse than another’s. But we’re inclined to give this a Satisfactory rating, since the rest of the release is well-hedged and caveated.

Total Score: 8 of 10 Satisfactory

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