Multicomponent strategy with decentralised molecular testing for tuberculosis in Uganda: a cost and cost-effectiveness analysis

Impact of a multicomponent strategy including decentralized molecular testing for tuberculosis on mortality: planned analysis of a cluster-randomized trial in Uganda

Background

Rapid diagnosis of tuberculosis (TB) is important for improving outcomes and reducing transmission. Previous studies assessing the impact of Xpert MTB/RIF (Xpert), a molecular assay that provides results within 2 h, on mortality have been inconclusive. In this planned analysis of a pragmatic cluster-randomized trial in Uganda, we assessed whether a multicomponent strategy, including decentralized Xpert testing, decreased mortality among adults evaluated for TB.

Methods

Ten community health centers were randomized, using a computer-generated randomization sequence, to the XPEL-TB intervention (on-site Xpert testing plus implementation supports) and ten to routine TB care without any modifications (on-site smear microscopy and referral-based Xpert testing for selected patients). The trial included all adults ( ≥ 18 years of age) undergoing evaluation for presumptive TB at each trial health center. All-cause mortality was a secondary outcome of the trial. For this analysis, the primary outcome was the mortality rate (censored at 18 months), and the secondary outcome was the six-month mortality risk. We compared the outcomes between trial arms using cluster-level analyses to account for stratified randomization and patient-level covariates. The trial was registered with the US National Institutes of Health (identifier: NCT03044158) and the Pan African Clinical Trials Registry (identifier: PACTR201610001763265).

Findings

Vital status was ascertained for 8413 of 9563 (88%) XPEL-TB trial participants who presented at the health centers from October 22, 2018 through February 29, 2020. The adjusted rate ratio (aRR) was 0.77 (95% CI: 0.47-1.28), comparing the intervention (145 deaths/3655 person-years) to routine care (154 deaths/3015 person-years). In sub-group analyses, point estimates for mortality were lower in the intervention arm among people without HIV (aRR = 0.50, 95% CI: 0.26-0.96) and among females (aRR = 0.64, 95% CI: 0.33-1.23). The mortality risk analysis yielded similar results.

Interpretation

Consistent point estimates favoring the intervention in our trial and previous ones suggest that Xpert testing may have an impact on mortality at community health centers. However, the magnitude of effect is small, and statistically significant results are unlikely to be attained within a single trial. Future trials of novel TB diagnostics at community health centers should focus on more proximal outcomes including TB detection and treatment initiation.

Funding

This work was supported by the National Heart, Lung, and Blood Institute of the US National Institutes of Health under award number R01HL130192.

Interventions and implementation considerations for reducing pre-treatment loss to follow-up in adults with pulmonary tuberculosis: A scoping review

Background

Tuberculosis (TB) is a leading cause of death worldwide with over 90% of reported cases occurring in low- and middle-income countries (LMICs). Pre-treatment loss to follow-up (PTLFU) is a key contributor to TB mortality and infection transmission.

Objectives

We performed a scoping review to map available evidence on interventions to reduce PTLFU in adults with pulmonary TB, identify gaps in existing knowledge, and develop a conceptual framework to guide intervention implementation.

Methods

We searched eight electronic databases up to February 6 2024, medRxiv for pre-prints, and reference lists of included studies. Two review authors independently selected studies and extracted data using a predesigned form. We analysed data descriptively, presented findings in a narrative summary and developed a conceptual framework based on the Practical, Robust Implementation, and Sustainability Model to map the factors for effective intervention implementation.

Results

We reviewed 1262 records and included 17 studies. Most studies were randomized controlled trials (8/17, 47%). Intervention barriers included stigma and inadequate resources; enablers included mobile phones and TB testing and results on the same day. We identified eight interventions that reduced PTLFU: treatment support groups; mobile notifications; community health workers; integrated HIV/TB services; Xpert MTB/RIF as the initial diagnostic test; computer-aided detection with chest radiography screening; active linkage to care; and multi-component strategies.

Conclusion

Given the variation of healthcare settings, TB programs should consider contextual factors such as user acceptability, political commitment, resources, and infrastructure before adopting an intervention. Future research should utilize qualitative study designs, be people-centred, and include social and economic factors affecting PTLFU.

USING SPUTUM AND TONGUE SWAB SPECIMENS FOR IN-HOME POINT-OF-CARE TARGETED UNIVERSAL TESTING FOR TB OF HOUSEHOLD CONTACTS: AN ACCEPTABILITY AND FEASIBILITY ANALYSIS

Introduction

Effective strategies are needed to facilitate early detection and diagnosis of tuberculosis (TB). The overreliance on passive case detection, symptom screening, and collection of sputum, results in delayed or undiagnosed TB, which directly contributes to on-going TB transmission. We assessed the acceptability and feasibility of in-home, Targeted Universal TB Testing (TUTT) of household contacts using GeneXpert MTB/RIF Ultra at point-of-care (POC) during household contact investigations (HCIs) and compared the feasibility of using sputum vs. tongue swab specimens.

Methods

Household contacts (HHCs) receiving in-home POC TUTT as part of the TB Home Study were asked to complete a post-test acceptability survey. The survey explored HHC's level of comfort, confidence in the test results, and the perceived appropriateness of in-home POC TUTT. We used the Metrics to Assess the Feasibility of Rapid Point-of-Care Technologies framework to assess the feasibility of using sputum and tongue swab specimens for in-home POC TUTT. Descriptive statistics were used to report participant responses and feasibility metrics.

Results

Of 313 eligible HHCs, 267/313 (85.3%) consented to in-home POC TUTT. Of those, 267/267 (100%) provided a tongue swab and 46/267 (17.2%) could expectorate sputum. All specimens were successfully prepared for immediate, in-home testing with Xpert Ultra on GeneXpert Edge. Of 164 tongue swab tests conducted, 160/164 (97.6%) generated a valid test result compared to 44/46 (95.7%) sputum-based tests. An immediate test result was available for 262/267 (98.1%) individuals based on in-home swab testing, and 44/46 (95.7%) based on in-home sputum testing. The mean in-home POC TUTT acceptability score (5=highly acceptable) was 4.5/5 (SD= 0.2).

Conclusion

In-home, POC TUTT using either sputum or tongue swab specimens was highly acceptable and feasible. Tongue swab specimens greatly increase the proportion of HHCs tested compared to sputum. In-home POC TUTT using a combination of sputum and tongue swabs can mitigate shortcomings to case detection.

Sputum and tongue swab molecular testing for the in-home diagnosis of tuberculosis in unselected household contacts: a cost and cost-effectiveness analysis

Background

Delayed and missed diagnosis are a persistent barrier to tuberculosis control, partly driven by limitations associated with sputum collection and an unmet need for decentralized testing. Household contact investigation with point-of-care testing of non-invasive specimens like tongue swabs are hitherto undescribed and may be a cost-effective solution to enable community-based active case finding.

Methods

In-home, molecular point-of-care testing was conducted using sputum and tongue specimens collected from all household contacts of confirmed tuberculosis cases. A health economic assessment was executed to estimate and compare the cost and cost-effectiveness of different in-home, point-of-care testing strategies. Incremental cost effectiveness ratios of strategies utilizing different combination testing algorithms using sputum and/or tongue swab specimens were compared.

Findings

The total implementation cost of delivering the standard of care for a 2-year period was $84 962. Strategies integrating in-home point-of-care testing ranged between $87 844 - $93 969. The cost-per-test for in-home, POC testing of sputum was the highest at $20·08 per test. Two strategies, Point-of-Care Sputum Testing and Point-of-Care Combined Sputum and Individual Tongue Swab Testing were the most cost-effective with ICERs of $543·74 and $547·29 respectively, both below a $2,760 willingness-to-pay threshold.

Interpretation

An in-home, point-of-care molecular testing strategy utilizing combination testing of tongue swabs and sputum specimens would incur an additional 10.6% program cost, compared to SOC, over a 2-year period. The increased sample yield from tongue swabs combined with immediate result notification following, in-home POC testing would increase the number of new TB cases detected and linked to care by more than 800%.

In-home TB Testing Using GeneXpert Edge is Acceptable, Feasible, and Improves the Proportion of Symptomatic Household Contacts Tested for TB: A Proof-of-Concept Study

Background

Household contact investigations are effective for finding tuberculosis (TB) cases but are hindered by low referral uptake for clinic-based evaluation and testing. We assessed the acceptability and feasibility of in-home testing of household contacts (HHC) using the GeneXpert Edge platform.

Methods

We conducted a 2-arm, randomized study in Eastern Cape, South Africa. HHCs were verbally assessed using the World Health Organization-recommended 4-symptom screen. Households with ≥1 eligible symptomatic contact were randomized. Intervention households received in-home GeneXpert MTB/RIF molecular testing. GeneXpert-positive HHCs were referred for clinic-based treatment. Standard-of-care households were referred for clinic-based sputum collection and testing. We defined acceptability as agreeing to in-home testing and feasibility as generation of valid Xpert MTB/RIF results. The proportion and timeliness of test results received was compared between groups.

Results

Eighty-four households were randomized (n = 42 per arm). Of 100 eligible HHCs identified, 98/100 (98%) provided consent. Of 51 HHCs allocated to the intervention arm, all accepted in-home testing; of those, 24/51 (47%) were sputum productive and 23/24 (96%) received their test results. Of 47 HCCs allocated to standard-of-care, 7 (15%) presented for clinic-based TB evaluation, 6/47 (13%) were tested, and 4/6 (67%) returned for their results. The median (interquartile range) number of days from screening to receiving test results was 0 (0) and 16.5 (11-15) in the intervention and standard-of-care arms, respectively.

Conclusions

In-home testing for TB was acceptable, feasible, and increased HHCs with a molecular test result. In-home testing mitigates a major limitation of household contact investigations (dependency on clinic-based referral), revealing new strategies for enhancing early case detection.

Cost-effectiveness of diagnostic tools and strategies for the screening and diagnosis of tuberculosis disease and infection: a scoping review

The objective of this scoping review is to understand the cost-effectiveness of current and future tools/strategies for screening and diagnosis of tuberculosis (TB) infection and disease. To this end, PubMed, EMBASE and SCOPUS were used to identify any English language reports on the cost-effectiveness of TB infection/disease screening/diagnostic strategies published between 1 January 2017 and 7 October 2023. Studies included high-burden/risk TB populations, compared diagnostic/screening methods and conducted a cost-effectiveness/economic evaluation. We stratified the included articles in four groups (cost-effectiveness of diagnosing TB disease/infection and cost-effectiveness of screening for TB disease/infection). A full-text review was conducted, and relevant costing data extracted. Of the 2417 articles identified in the initial search, 112 duplicates were removed, and 2305 articles were screened for title and abstract. 23 full articles were reviewed, and 17 fulfilled all inclusion criteria. While sputum smear microscopy (SSM) has been the primary method of diagnosing TB disease in high-burden countries, the current body of literature suggests that SSM is likely to be the least cost-effective tool for the diagnosis of TB disease. Further scale-up with molecular diagnostics, such as GeneXpert and Truenat, was shown to be broadly cost-effective, with a multitest approach likely to be cost-effective for both screening and diagnosis. There is an urgent need to increase access and remove barriers to implementation of diagnostics that have been repeatedly shown to be cost-effective, as well as to develop new diagnostic and screening technologies/strategies to address current barriers to scale-up.

A Generalizable Decision-Making Framework for Selecting Onsite versus Send-out Clinical Laboratory Testing

BACKGROUND

Laboratory networks provide services through onsite testing or through specimen transport to higher-tier laboratories. This decision is based on the interplay of testing characteristics, treatment characteristics, and epidemiological characteristics.

OBJECTIVES

Our objective was to develop a generalizable model using the threshold approach to medical decision making to inform test placement decisions.

METHODS

We developed a decision model to compare the incremental utility of onsite versus send-out testing for clinical purposes. We then performed Monte Carlo simulations to identify the settings under which each strategy would be preferred. Tuberculosis was modeled as an exemplar.

RESULTS

The most important determinants of the decision to test onsite versus send-out were the clinical utility lost due to send-out testing delays and the accuracy decrement with onsite testing. When the sensitivity decrements of onsite testing were minimal, onsite testing tended to be preferred when send-out delays reduced clinical utility by >20%. By contrast, when onsite testing incurred large reductions in sensitivity, onsite testing tended to be preferred when utility lost due to delays was >50%. The relative cost of onsite versus send-out testing affected these thresholds, particularly when testing costs were >10% of treatment costs.

CONCLUSIONS

Decision makers can select onsite versus send-out testing in an evidence-based fashion using estimates of the percentage of clinical utility lost due to send-out delays and the relative accuracy of onsite versus send-out testing. This model is designed to be generalizable to a wide variety of use cases.

HIGHLIGHTS

The design of laboratory networks, including the decision to place diagnostic instruments at the point-of-care or at higher tiers as accessed through specimen transport, can be informed using the threshold approach to medical decision making.The most important determinants of the decision to test onsite versus send-out were the clinical utility lost due to send-out testing delays and the accuracy decrement with onsite testing.The threshold approach to medical decision making can be used to compare point-of-care testing accuracy decrements with the lost utility of treatment due to send-out testing delays.The relative cost of onsite versus send-out testing affected these thresholds, particularly when testing costs were >10% of treatment costs.

Cost-effectiveness and budget impact of decentralising childhood tuberculosis diagnosis in six high tuberculosis incidence countries: a mathematical modelling study

Background

The burden of childhood tuberculosis remains high globally, largely due to under-diagnosis. Decentralising childhood tuberculosis diagnosis services to lower health system levels could improve case detection, but there is little empirically based evidence on cost-effectiveness or budget impact.

Methods

In this mathematical modelling study, we assessed the cost-effectiveness and budget impact of decentralising a comprehensive diagnosis package for childhood tuberculosis to district hospitals (DH-focused) or primary health centres (PHC-focused) compared to standard of care (SOC). The project was conducted in Cambodia, Cameroon, Côte d'Ivoire, Mozambique, Sierra Leone, and Uganda between August 1st, 2018 and September 30th, 2021. A mathematical model was developed to assess the health and economic outcomes of the intervention from a health system perspective. Estimated outcomes were tuberculosis cases, deaths, disability-adjusted life years (DALYs) and incremental cost-effectiveness ratios (ICERs). We also calculated the budget impact of nationwide implementation. The TB-Speed Decentralization study is registered with ClinicalTrials.gov, NCT04038632.

Findings

For the DH-focused strategy versus SOC, ICERs ranged between $263 (Cambodia) and $342 (Côte d'Ivoire) per DALY averted. For the PHC-focused strategy versus SOC, ICERs ranged between $477 (Cambodia) and $599 (Côte d'Ivoire) per DALY averted. Results were sensitive to TB prevalence and the discount rate used. The additional costs of implementing the DH-focused strategy ranged between $12.8 M (range 10.8-16.4) (Cambodia) and $50.4 M (36.5-74.4) (Mozambique), and between $13.9 M (12.6-15.6) (Sierra Leone) and $134.6 M (127.1-143.0) (Uganda) for the PHC-focused strategy.

Interpretation

The DH-focused strategy may be cost-effective in some countries, depending on the cost-effectiveness threshold used for policy making. Either intervention would require substantial early investment.

Funding

Unitaid.

Cost-effectiveness of Low-complexity Screening Tests in Community-based Case-finding for Tuberculosis

INTRODUCTION

In high-burden settings, low-complexity screening tests for tuberculosis (TB) could expand the reach of community-based case-finding efforts. The potential costs and cost-effectiveness of approaches incorporating these tests are poorly understood.

METHODS

We developed a microsimulation model assessing 3 approaches to community-based case-finding in hypothetical populations (India-, South Africa-, The Philippines-, Uganda-, and Vietnam-like settings) with TB prevalence 4 times that of national estimates: (1) screening with a point-of-care C-reactive protein (CRP) test, (2) screening with a more sensitive "Hypothetical Screening test" (95% sensitive for Xpert Ultra-positive TB, 70% specificity; equipment/labor costs similar to Xpert Ultra, but using a $2 cartridge) followed by sputum Xpert Ultra if positive, or (3) testing all individuals with sputum Xpert Ultra. Costs are expressed in 2023 US dollars and include treatment costs.

RESULTS

Universal Xpert Ultra was estimated to cost a mean $4.0 million (95% uncertainty range: $3.5 to $4.6 million) and avert 3200 (2600 to 3900) TB-related disability-adjusted life years (DALYs) per 100 000 people screened ($670 [The Philippines] to $2000 [Vietnam] per DALY averted). CRP was projected to cost $550 (The Philippines) to $1500 (Vietnam) per DALY averted but with 44% fewer DALYs averted. The Hypothetical Screening test showed minimal benefit compared to universal Xpert Ultra, but if specificity were improved to 95% and per-test cost to $4.5 (all-inclusive), this strategy could cost $390 (The Philippines) to $940 (Vietnam) per DALY averted.

CONCLUSIONS

Screening tests can meaningfully improve the cost-effectiveness of community-based case-finding for TB but only if they are sensitive, specific, and inexpensive.

The value of histopathology combined with CapitalBio Mycobacterium real-time polymerase chain reaction test for diagnosing spinal tuberculosis

Purpose

To evaluate the diagnostic efficacy of CapitalBio Mycobacterium real-time polymerase chain reaction assay (CapitalBio test) in spinal tuberculosis (STB). The value of histopathology combined with the CapitalBio test in diagnosing STB was also assessed.

Methods

We retrospectively analyzed the medical information of suspected STB. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of histopathology, CapitalBio test, and histopathology combined with CapitalBio test were calculated to evaluate their diagnostic efficacy compared with a composite reference standard.

Results

A total of 222 suspected STB patients were included in the study. The sensitivity, specificity, PPV, NPV, and AUC of histopathology for STB were recorded to be 62.0, 98.0, 97.4, 68.3%, and 0.80, respectively. The sensitivity, specificity, PPV, NPV, and AUC of the CapitalBio test were 75.2, 98.0, 97.9, 76.7%, and 0.87, respectively, while that of histopathology combined with the CapitalBio test was 81.0, 96.0, 96.1, 80.8%, and 0.89, respectively.

Conclusion

Histopathology and CapitalBio test exhibited high accuracy and are recommended in diagnosing STB. Histopathology combined with the CapitalBio test might give the best efficacy in STB diagnosis.