Radio+ TB: Determining the optimal regimen for bacteriologically negative, radiographically apparent TB diagnosed using new tests
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Date
2021-05-12
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Kamuzu University of Health Sciences
Abstract
The type of research study: Prospective cohort study. The problem to be studied
A proportion of patients presenting for assessment with pulmonary tuberculosis (TB)
symptoms will have a negative sputum Xpert but will in fact have undiagnosed active TB or
be at high risk of progression to active disease. This group is currently ineffectively
managed. This study aims to evaluate novel field ready-diagnostic to assist in the diagnosis
of Xpert negative TB.
Broad objective: To determine a baseline screen strategy utilising novel diagnostics in patients presenting
with symptoms to primary care that has a high predictive value for prevalent and incident
culture positive TB and to establish patient and provider attitudes to treatment approaches
on the basis of these novel tests.
Specific objectives:
1. To determine the predictive value of chest x-ray computer-aided diagnostics (CXR
CAD), TB host response blood test and face mask sampling for prevalent and incident
culture positive TB, alone and in combination, in participants presenting to primary
care with TB symptoms.
2. To use qualitative research methods to identify factors most relevant to patients in
the diagnosis and management of bacteriologically-negative TB.
3. To measure patient and provider preferences for different diagnostic and treatment
strategies for bacteriologically negative TB through a discrete choice experiment to
inform a future randomised control trial design
4. To explore whether diagnostic and treatment preferences vary by individual or TB
disease characteristics
Methodology: A prospective cohort study for a diagnostic evaluation will be undertaken. Participants will
be 200 adults with symptoms of TB presenting to Bangwe Health Centre for assessment of
acute illness. Following consent, they will undergo investigation for TB using both routine
(CXR, sputum Xpert) additional (Xpert Ultra and induced sputum culture) and research tests
(Computer-aided X-ray diagnosis evaluation with 3 different software packages - Lunit,
CAD4TB, Qure.ai; TB host response test; face mask sampling). Clinic staff will be provided
with the results of routine and additional tests to inform patient management. Participants will return at 3 months for reassessment, with no further assessments planned. The primary
outcome will be prevalence of microbiologically-confirmed TB at recruitment, and incidence
of microbiologically-confirmed TB over 3 months of follow-up.
We will also undertake a cross-sectional discrete choice experiment survey to investigate
patient and provider preferences for treatment choices around insipient TB infection. A
qualitative study will be undertaken to develop survey for the discrete choice experiments.
Expected findings and their dissemination
We expect high rates of CXR abnormalities and that these will be highly sensitive for
prevalent/incident TB but not specific. We anticipate that adding a TB HR Blood tests or face
mask sampling will increase positive predictive value for prevalent/incident TB. Results will
be disseminated to patients and clinic staff through MLW Science Communication
Department, to COMREC, to the Blantyre District Health Office, to the Malawi National TB
Programme, and locally and internationally through presentations and peer-reviewed
journal publications.