RID-TB:Dx
Research type
Research Study
Full title
Research to Improve the Detection and Treatment of Latent Tuberculosis Infection: Diagnostics (RID-TB:Dx) A randomised controlled trial to evaluate the effectiveness of using the RD-1 based C Tb skin test as a replacement for blood-based interferon-γ release assay for detection of latent TB infection and initiation of TB preventive treatment in the UK
IRAS ID
269485
Contact name
Ellen Owen-Powell
Contact email
Sponsor organisation
University College London
Eudract number
2019-002592-34
Duration of Study in the UK
3 years, 0 months, 1 days
Research summary
Research Summary:
Title: A randomised controlled trial to evaluate the effectiveness of using the RD-1 based C Tb skin test as a replacement for blood-based interferon-γ release assay for detection of latent TB infection and initiation of TB preventive treatment in the UK
Summary: Latent TB infection (LTBI) testing and treatment reduces TB incidence by preventing reactivation, and is expected to be cost-saving to the health system. However, high rates of testing, treatment uptake and treatment completion are essential to achieve these benefits. In 2011 TB guidelines stated that a blood test for LTBI provided good value for money. However, more recent analysis suggests that a skin test (tuberculin skin test, TST) may be better value. The LTBI screening programme conveniently uses blood tests, called interferon-gamma release assays (IGRA). The TST may not always correctly identify who has LTBI as reliably as IGRA. This can lead to unnecessary treatment if results are falsely positive. There is now a new skin test available, called C-Tb, which research suggests is as good as IGRA in correctly identifying LTBI. In a three-year randomised study, we propose to compare the C-Tb test to usual care using IGRA to see whether it is more accurate, easier to obtain a diagnosis, and offers better value for money for the NHS. We will also do research to understand what people think of C-Tb, and their experience of testing for LTBI. We will invite people who have a high risk of developing TB disease to take part. People will be invited from the community, general practice or hospitals.
The study is part of a 5-year NIHR-funded programme of research to improve access to diagnosis and enhance treatment uptake and completion in individuals with or at risk of LTBI in England.
Summary of results:
Background and Purpose Tuberculosis (TB) remains a major health concern in the UK. To stop the spread of TB, it is vital to find and treat people with "latent TB infection." This is when a person has the TB bacteria in their body but is not ill and cannot pass it on to others. If left untreated, the infection can become "active" and make the person very sick.
Currently, the standard test in the UK is a blood test. A new skin test called Cy-TB has been developed. It is as accurate as the blood test but requires an injection into the skin and a follow-up visit 2 to 3 days later to check the result. This study aimed to see if people would be happy to use this skin test and if it would help more people start the treatment needed to prevent them from getting sick.How the Study Was Conducted
The study took place in England between 2021 and 2024. Researchers invited 353 people who were eligible for TB screening, and 126 people joined the study. Participants were put into two groups by chance:
1. The Skin Test Group: Offered the new Cy-TB skin test.
2. The Blood Test Group: Offered the standard blood test.
In the second half of the study, people in the skin test group were given the choice to have the blood test instead if they preferred.Main Findings
• Preferences: Most people preferred the blood test. The main reason was that they did not want to come back to the clinic a second time to have the skin test result checked.
• Testing Success: When people did choose the skin test, it worked well. All tests were successfully read by medical staff.
• Starting Treatment: Interestingly, the people who had the skin test and were found to have the infection were more likely to actually start their preventive medication compared to those who had the blood test. However, because we were able to enroll a small group of 126 people, we cannot be certain that this would be the same for everyone. We would need to look at a much larger group of people to be sure.
• Safety: The skin test was found to be safe. Only two people had very mild reactions where the needle went in (such as redness or itching), and there were no serious side effects.Conclusions
The study shows that the Cy-TB skin test is a safe and effective way to find TB infection and help people start treatment. However, because it requires two visits to the clinic, most people in the UK still prefer a single blood test. For the skin test to be useful in the NHS, we need to find ways to make the second visit easier for people.https://gbr01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrack.pstmrk.it%2F3ts%2Fwww.clinicaltrialsregister.eu%252Fctr-search%252Ftrial%252F2019-002592-34%252Fresults%2FNBTI%2FT8vDAQ%2FAQ%2F229eb4ed-1eb8-4d2c-881f-66da813b4d6f%2F1%2F-C872kzzs1&data=05%7C02%7Charrow.rec%40hra.nhs.uk%7Cd7f1916fe35d4e1c362108de7a049c32%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C639082357407999554%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=1PZBaTYd6lVouBdge4Ydhlo6E4k91tO7xUzEbPflOdA%3D&reserved=0 https://gbr01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrack.pstmrk.it%2F3ts%2Fwww.isrctn.com%252FISRCTN17936038%2FNBTI%2FT8vDAQ%2FAQ%2F229eb4ed-1eb8-4d2c-881f-66da813b4d6f%2F2%2F1avksDyq8Z&data=05%7C02%7Charrow.rec%40hra.nhs.uk%7Cd7f1916fe35d4e1c362108de7a049c32%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C639082357408030789%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=SiI0GyTTnGWfk%2FMvMEMb%2F4u%2F%2FQ%2F4%2BJGBS0AmGxCq7Dk%3D&reserved=0
REC name
London - Harrow Research Ethics Committee
REC reference
19/LO/1624
Date of REC Opinion
3 Jan 2020
REC opinion
Further Information Favourable Opinion