Study protocol: a pragmatic, cluster-randomized controlled trial to evaluate the effect of implementation of the Truenat platform/MTB assays at primary health care clinics in Mozambique and Tanzania (TB-CAPT CORE)

BACKGROUND

In 2020, the WHO-approved Molbio Truenat platform and MTB assays to detect Mycobacterium tuberculosis complex (MTB) and resistance to rifampicin directly on sputum specimens. This primary health care center-based trial in Mozambique and Tanzania investigates the effect of Truenat platform/MTB assays (intervention arm) combined with rapid communication of results compared to standard of care on TB diagnosis and treatment initiation for microbiologically confirmed TB at 7 days from enrolment.

METHODS

The Tuberculosis Close the Gap, Increase Access, and Provide Adequate Therapy (TB-CAPT) CORE trial employs a pragmatic cluster randomized controlled design to evaluate the impact of a streamlined strategy for delivery of Truenat platform/MTB assays testing at primary health centers. Twenty-nine centers equipped with TB microscopy units were selected to participate in the trial. Among them, fifteen health centers were randomized to the intervention arm (which involves onsite molecular testing using Truenat platform/MTB assays, process process optimization to enable same-day TB diagnosis and treatment initiation, and feedback on Molbio platform performance) or the control arm (which follows routine care, including on-site sputum smear microscopy and the referral of sputum samples to off-site Xpert testing sites). The primary outcome of the study is the absolute number and proportion of participants with TB microbiological confirmation starting TB treatment within 7 days of their first visit. Secondary outcomes include time to bacteriological confirmation, health outcomes up to 60 days from first visit, as well as user preferences, direct cost, and productivity analyses.

ETHICS AND DISSEMINATION

TB-CAPT CORE trial has been approved by regulatory and ethical committees in Mozambique and Tanzania, as well as by each partner organization. Consent is informed and voluntary, and confidentiality of participants is maintained throughout. Study findings will be presented at scientific conferences and published in peer-reviewed international journals.

TRIAL REGISTRATION

US National Institutes of Health's ClinicalTrials.gov, NCT04568954. Registered 23 September 2020.

The rise of artificial intelligence reading of chest X-rays for enhanced TB diagnosis and elimination

We provide an overview of the latest evidence on computer-aided detection (CAD) software for automated interpretation of chest radiographs (CXRs) for TB detection. CAD is a useful tool that can assist in rapid and consistent CXR interpretation for TB. CAD can achieve high sensitivity TB detection among people seeking care with symptoms of TB and in population-based screening, has accuracy on-par with human readers. However, implementation challenges remain. Due to diagnostic heterogeneity between settings and sub-populations, users need to select threshold scores rather than use pre-specified ones, but some sites may lack the resources and data to do so. Efficient standardisation is further complicated by frequent updates and new CAD versions, which also challenges implementation and comparison. CAD has not been validated for TB diagnosis in children and its accuracy for identifying non-TB abnormalities remains to be evaluated. A number of economic and political issues also remain to be addressed through regulation for CAD to avoid furthering health inequities. Although CAD-based CXR analysis has proven remarkably accurate for TB detection in adults, the above issues need to be addressed to ensure that the technology meets the needs of high-burden settings and vulnerable sub-populations.

TB disease patterns by HIV and diabetes status

BACKGROUND: TB is commonly categorised as pulmonary (PTB) or extrapulmonary TB (EPTB). Knowledge of TB disease patterns (PTB and/or EPTB) and determining risk factors remains limited.METHODS: This was a prospective cohort study using point-of-care ultrasound (POCUS) in Indian patients with presumed TB. Clinical and imaging data were used to develop refined case definitions for PTB, concurrent PTB and EPTB (PTB + EPTB) and EPTB without PTB (EPTB). These groups were analysed by HIV (HIV+/-) and diabetes mellitus (DM+/-) status.RESULTS: Of 172 HIV-/DM- patients with TB, 48% had PTB, 23% PTB + EPTB and 29% had EPTB, totalling 52% with any EPTB (PTB + EPTB or EPTB). In HIV+/DM- patients with TB (n = 35), 6% had PTB, 40% had PTB + EPTB and 54% had EPTB, accounting for 94% with EPTB. In HIV-/DM+ patients with TB (n = 61), 61% had PTB, 28% had PTB + EPTB and 11% had EPTB, representing 39% with EPTB.CONCLUSION: Refined case definitions revealed high proportions of EPTB even without HIV or DM. HIV further altered the TB disease pattern towards EPTB and DM towards PTB. Therefore, the dichotomy between PTB or EPTB does not represent the actual spectrum of TB disease. EPTB should receive higher priority in research and clinical practice.

The impact of changing the diagnostic algorithm for TB in Manicaland, Zimbabwe

SETTING

Governmental health facilities performing TB diagnostics in Manicaland, Zimbabwe.

OBJECTIVE

To investigate the effect of making Xpert® MTB/RIF the primary TB diagnostic for all patients presenting with presumptive TB on 1) the number of samples investigated for TB, 2) the proportion testing TB-positive, and 3) the proportion of unsuccessful results over time.

DESIGN

This retrospective study used data from GeneX-pert downloads, laboratory registers and quality assurance reports between 1 January 2017 and 31 December 2018.

RESULTS

The total number of Xpert tests performed in Manicaland increased from 3,967 in the first quarter of 2017 to 7,011 in the last quarter of 2018. Mycobacterium tuberculosis DNA was detected in 4.9-8.6% of the samples investigated using Xpert, with a higher yield in 2017 than in 2018. The overall proportion of unsuccessful Xpert assays due to "no results", errors and invalid results was 6.3%, and highly variable across sites.

CONCLUSION

Roll out of more sensitive TB diagnostics does not necessarily result in an increase of microbiologically confirmed TB diagnosis. While the number of samples tested using Xpert increased, the proportion of TB-positive tests decreased. GeneXpert soft- and hardware infrastructure needs to be strengthened to reduce the rate of unsuccessful assays and therefore, costs and staff time.

Diagnostic accuracy of the Xpert® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

SETTING

Xpert® MTB/RIF is the most widely used molecular assay for rapid diagnosis of tuberculosis (TB). The number of polymerase chain reaction cycles after which detectable product is generated (cycle threshold value, CT) correlates with the bacillary burden.OBJECTIVE To investigate the association between Xpert CT values and smear status through a systematic review and individual-level data meta-analysis.

DESIGN

Studies on the association between CT values and smear status were included in a descriptive systematic review. Authors of studies including smear, culture and Xpert results were asked for individual-level data, and receiver operating characteristic curves were calculated.

RESULTS

Of 918 citations, 10 were included in the descriptive systematic review. Fifteen data sets from studies potentially relevant for individual-level data meta-analysis provided individual-level data (7511 samples from 4447 patients); 1212 patients had positive Xpert results for at least one respiratory sample (1859 samples overall). ROC analysis revealed an area under the curve (AUC) of 0.85 (95%CI 0.82-0.87). Cut-off CT values of 27.7 and 31.8 yielded sensitivities of 85% (95%CI 83-87) and 95% (95%CI 94-96) and specificities of 67% (95%CI 66-77) and 35% (95%CI 30-41) for smear-positive samples.

CONCLUSION

Xpert CT values and smear status were strongly associated. However, diagnostic accuracy at set cut-off CT values of 27.7 or 31.8 would not replace smear microscopy. How CT values compare with smear microscopy in predicting infectiousness remains to be seen.

Market assessment of tuberculosis diagnostics in India in 2013

BACKGROUND

India represents a significant potential market for new tests. We assessed India's market for tuberculosis (TB) diagnostics in 2013.

METHODS

Test volumes and unit costs were assessed for tuberculin tests, interferon-gamma release assays, sputum smear microscopy, serology, culture, speciation testing, nucleic-acid amplification tests (i.e., in-house polymerase chain reaction, Xpert(®) MTB/RIF, line-probe assays) and drug susceptibility testing. Data from the public sector were collected from the Revised National TB Control Programme reports. Private sector data were collected through a survey of private laboratories and practitioners. Data were also collected from manufacturers.

RESULTS

In 2013, India's public sector performed 19.2 million tests, with a market value of US$22.9 million. The private sector performed 13.6 million tests, with a market value of US$60.4 million when prices charged to the patient were applied. The overall market was US$70.8 million when unit costs from the ingredient approach were used for the 32.8 million TB tests performed in the entire country. Smear microscopy was the most common test performed, accounting for 25% of the overall market value.

CONCLUSION

India's estimated market value for TB diagnostics in 2013 was US$70.8 million. These data should be of relevance to test developers, donors and implementers.

Market assessment of tuberculosis diagnostics in China in 2012

OBJECTIVE

To assess the 2012 served available market for tuberculosis (TB) diagnostics in China in the sector served by the China Centre for Disease Control and Prevention (CDC) and the hospital sector in China, including both designated TB hospitals and general hospitals.

DESIGN

Test volumes and unit costs were assessed for tuberculin skin tests, interferon-gamma release assays (IGRAs), smear microscopy, serology, cultures, speciation tests, nucleic-acid amplification tests (NAATs), drug susceptibility tests and adenosine-deaminase tests (ADA). Data were obtained from electronic databases (CDC sector) and through surveys (hospital sector), and were estimated for the two sectors and for the country as a whole. Test costs were estimated by staff at China CDC, and using published literature.

RESULTS

In 2012, the China CDC and hospital sectors performed a total of 44 million TB diagnostic tests at an overall value of US$294 million. Tests used by the CDC sector were smear microscopy, solid and liquid culture and DST, while the hospital sector also used IGRAs, NAATs, ADA and serology. The hospital sector accounted for 76% of the overall test volume and 94% of the market value.

CONCLUSION

China has a very large TB diagnostic market that encompasses a wide range of diagnostic tests, with the majority being performed in Chinese hospitals.

Mobile health to improve tuberculosis care and control: a call worth making

The use of mobile phones has substantially increased throughout the world over the last decade. This has opened up opportunities for the integration of mobile phones as health intervention tools in many aspects of health care, including prevention, diagnosis, data collection, treatment and adherence monitoring and surveillance. Several applications have been explored in human immunodeficiency virus care. The field of tuberculosis (TB) has not exploited the potential of mobile health (m-health) to the same extent, although the opportunities have been recognized. A number of proof-of-concept and pilot studies have been published on m-health in TB care, and an even larger number of studies are available in the grey literature. This article summarizes publications and recent developments at the intersection of TB care and m-health. We show that more rigorous studies evaluating different applications and implementation strategies are needed to establish an evidence base that serves to inform policy and decision making. We outline further areas of research that should be addressed and potential challenges that lie ahead if m-health applications are to enhance the accessibility and quality of TB care.

Cryptosporidium parvum-associated sclerosing cholangitis in a liver transplant patient

Cryptosporidium parvum causes severe long-standing diarrhea in immunocompromised patients. Sclerosing cholangitis caused by C. parvum is a rare complication in transplant recipients. We report herein the presentation of Cryptosporidium-associated cholangitis in an adult liver transplant patient diagnosed by liver biopsy. The patient improved on treatment with azithromycin and paromomycin.