Which new diagnostics for tuberculosis, and when?

Impact of molecular diagnostic tests on diagnostic and treatment delays in tuberculosis: a systematic review and meta-analysis

BACKGROUND

Countries with high TB burden have expanded access to molecular diagnostic tests. However, their impact on reducing delays in TB diagnosis and treatment has not been assessed. Our primary aim was to summarize the quantitative evidence on the impact of nucleic acid amplification tests (NAAT) on diagnostic and treatment delays compared to that of the standard of care for drug-sensitive and drug-resistant tuberculosis (DS-TB and DR-TB).

METHODS

We searched MEDLINE, EMBASE, Web of Science, and the Global Health databases (from their inception to October 12, 2020) and extracted time delay data for each test. We then analysed the diagnostic and treatment initiation delay separately for DS-TB and DR-TB by comparing smear vs Xpert for DS-TB and culture drug sensitivity testing (DST) vs line probe assay (LPA) for DR-TB. We conducted random effects meta-analyses of differences of the medians to quantify the difference in diagnostic and treatment initiation delay, and we investigated heterogeneity in effect estimates based on the period the test was used in, empiric treatment rate, HIV prevalence, healthcare level, and study design. We also evaluated methodological differences in assessing time delays.

RESULTS

A total of 45 studies were included in this review (DS = 26; DR = 20). We found considerable heterogeneity in the definition and reporting of time delays across the studies. For DS-TB, the use of Xpert reduced diagnostic delay by 1.79 days (95% CI - 0.27 to 3.85) and treatment initiation delay by 2.55 days (95% CI 0.54-4.56) in comparison to sputum microscopy. For DR-TB, use of LPAs reduced diagnostic delay by 40.09 days (95% CI 26.82-53.37) and treatment initiation delay by 45.32 days (95% CI 30.27-60.37) in comparison to any culture DST methods.

CONCLUSIONS

Our findings indicate that the use of World Health Organization recommended diagnostics for TB reduced delays in diagnosing and initiating TB treatment. Future studies evaluating performance and impact of diagnostics should consider reporting time delay estimates based on the standardized reporting framework.

Tuberculosis Phenotypic and Genotypic Drug Susceptibility Testing and Immunodiagnostics: A Review

Tuberculosis (TB), considered an ancient disease, is still killing one person every 21 seconds. Diagnosis of Mycobacterium tuberculosis (M.tb) still has many challenges, especially in low and middle-income countries with high burden disease rates. Over the last two decades, the amount of drug-resistant (DR)-TB cases has been increasing, from mono-resistant (mainly for isoniazid or rifampicin resistance) to extremely drug resistant TB. DR-TB is problematic to diagnose and treat, and thus, needs more resources to manage it. Together with+ TB clinical symptoms, phenotypic and genotypic diagnosis of TB includes a series of tests that can be used on different specimens to determine if a person has TB, as well as if the M.tb strain+ causing the disease is drug susceptible or resistant. Here, we review and discuss advantages and disadvantages of phenotypic vs. genotypic drug susceptibility testing for DR-TB, advances in TB immunodiagnostics, and propose a call to improve deployable and low-cost TB diagnostic tests to control the DR-TB burden, especially in light of the increase of the global burden of bacterial antimicrobial resistance, and the potentially long term impact of the coronavirus disease 2019 (COVID-19) disruption on TB programs.

Aligning diagnostics to the point-of-care: lessons for innovators, evaluators and decision-makers from tuberculosis and HIV

Diagnostics, including those that work at point-of-care, are an essential part of successful public health responses to infectious diseases and pandemics. Yet, they are not always used or fit intended use settings. This paper reports on key insights from a qualitative study on how those engaged with developing and implementing new point-of-care (POC) diagnostics for tuberculosis (TB) and HIV ensure these technologies work at POC. Ethnographic fieldwork between 2015 and 2017 consisting of 53 semistructured interviews with global stakeholders and visits to workshops, companies, and conferences was combined with 15 semistructured interviews with stakeholders in India including providers, decision-makers, scientists and developers and visits to companies, clinics and laboratories. Our results show how developers and implementer of HIV and TB POC diagnostics aim to know and align their diagnostics to elements in more settings than just intended use, but also the setting of the developer, the global intermediaries, the bug/disease and the competitor. Actors and elements across these five settings define what a good diagnostic is, yet their needs might conflict or change and they are difficult to access. Aligning diagnostics to the POC requires continuous needs assessment throughout development and implementation phases as well as substantive, ongoing investment in relationships with users. The flexibility required for such continuous realigning and iteration clashes with established evaluation procedures and business models in global health and risks favouring certain products over others. The paper concludes with suggestions to strengthen this alignment work and applies this framework to research needs in the wake of COVID-19.

Point-of-Care Testing in Microbiology: A Mechanism for Improving Patient Outcomes

BACKGROUND

Increasingly, demands for improved health and quality of life conflict with the realities of delivering healthcare in an environment of higher expenditures, adherence to test utilization, and patient-centered experience. Patient-centered care is commonly identified as a goal of healthcare delivery, and yet healthcare systems struggle with delivery of care to patients, often failing to identify the seriously ill and capitalize on the predictive qualities of diagnostic testing. Point-of-care (POC) testing provides access to rapid diagnosis and predictive value key to realizing patient outcomes. An evaluation of cost-effective models and the clinical impact of POC testing for clinical microbiology is needed.

CONTENT

Accurate and rapid diagnostics have the potential to affect healthcare decisions to a degree well out of proportion to their cost. Contemporary healthcare models increasingly view POC testing as a mechanism for efficient deployment of healthcare. POC testing can deliver rapid diagnosis in environments where testing results can be used to direct management during patient visits and in areas where centralized laboratory testing may limit access to care. Nucleic acid assays, designed for POC testing, can match, or exceed, the sensitivity of conventional laboratory-based testing, eliminating the need for confirmation testing. Here, the goals of POC testing for microbiology, applications, and technologies, as well as outcomes and value propositions, are discussed.

SUMMARY

The combination of rapid reporting, an increasing array of organisms capable of causing disease, actionable resulting, and improved patient outcomes is key in the evolution of POC testing in clinical microbiology.

Early cost-effectiveness modeling for better decisions in public research investment of personalized medicine technologies

Millions of dollars are spent on the development of new personalized medicine technologies. While these research costs are often supported by public research funds, many diagnostic tests and biomarkers are not adopted by the healthcare system due to lack of evidence on their cost-effectiveness. We describe a stepwise approach to conducting cost-effectiveness analyses that are performed early in the technology's development process and can help mitigate the potential risks of investment. Decision analytic modeling can identify the key drivers of cost effectiveness and provide minimum criteria that the technology needs to meet for adoption by public and private healthcare systems. A value of information analysis can quantify the added value of conducting more research to provide further evidence for policy decisions. These steps will allow public research funders to make better decisions on their investments to maximize the health benefits and to minimize the number of suboptimal technologies.

Evaluation of the Impact of a Sequencing Assay for Detection of Drug Resistance on the Clinical Management of Tuberculosis

Background

In 2012, the California Department of Public Health began using pyrosequencing (PSQ) to detect mutations associated with resistance to isoniazid, rifampin, quinolones and injectable drugs in Mycobacterium tuberculosis complex. We evaluated the impact of the PSQ assay on the clinical management of tuberculosis (TB) in California.

Methods

TB surveillance and laboratory data for specimens submitted 1 August 2012 through 31 December 2016 were analyzed to determine time to effective treatment initiation. A survey of clinicians was used to assess how PSQ results influenced clinical decision making.

Results

Of 1957 specimens tested with PSQ, 52% were sediments and 46% were culture isolates, submitted a median of 8 and 35 days, respectively, after collection. Among 36 patients with multidrug-resistant (MDR) TB who had a sediment specimen submitted for PSQ, median time from specimen collection to MDR-TB treatment initiation was 12 days vs 51 days when PSQ was not used. Completed surveys were returned for 303 patients, 177 of whom reported a treatment change; 75 (42%) of clinicians reported PSQ as a reason for change. Twenty-one patients either had an MDR-TB risk factor and a smear-positive sputum specimen, but had PSQ performed on a culture isolate (9/36 [25%]); or did not have PSQ used for MDR-TB diagnosis (12/38 [32%]) and thus had an opportunity for earlier MDR-TB diagnosis with PSQ on sediment.

Conclusions

Patients with MDR-TB initiated effective treatment 5 weeks earlier when PSQ was used compared to those without PSQ. Survey data suggest clinicians use PSQ to devise effective TB drug regimens. To maximize the benefit of PSQ, earlier submission of specimens should be prioritized.

Performance of a cost-effective and automated blood counting system for resource-limited settings operated by trained and untrained users

Current flow-based blood counting devices require expensive and centralized medical infrastructure and are not appropriate for field use. In this article we report a streamlined, easy-to-use method to count red blood cells (RBC), white blood cells (WBC), platelets (PLT) and 3-part WBC differential through a cost-effective and automated image-based blood counting system. The approach consists of using a compact, custom-built microscope with large field-of-view to record bright-field and fluorescence images of samples that are diluted with a single, stable reagent mixture and counted using automatic algorithms. Sample collection utilizes volume-controlled capillary tubes, which are then dropped into a premixed, shelf-stable solution to stain and dilute in a single step. Sample measurement and analysis are fully automated, requiring no input from the user. Cost of the system is minimized through the use of custom-designed motorized components. We compare the performance of our system, as operated by trained and untrained users, to the clinical gold standard on 120 adult blood samples, demonstrating agreement within Clinical Laboratory Improvement Amendments guidelines, with no statistical difference in performance among different operator groups. The system's cost-effectiveness, automation and performance indicate that it can be successfully translated for use in low-resource settings where central hematology laboratories are not accessible.

Tuberculosis active case finding in Cambodia: a pragmatic, cost-effectiveness comparison of three implementation models

BACKGROUND

Globally, almost 40% of tuberculosis (TB) patients remain undiagnosed, and those that are diagnosed often experience prolonged delays before initiating correct treatment, leading to ongoing transmission. While there is a push for active case finding (ACF) to improve early detection and treatment of TB, there is extremely limited evidence about the relative cost-effectiveness of different ACF implementation models. Cambodia presents a unique opportunity for addressing this gap in evidence as ACF has been implemented using different models, but no comparisons have been conducted. The objective of our study is to contribute to knowledge and methodology on comparing cost-effectiveness of alternative ACF implementation models from the health service perspective, using programmatic data, in order to inform national policy and practice.

METHODS

We retrospectively compared three distinct ACF implementation models - door to door symptom screening in urban slums, checking contacts of TB patients, and door to door symptom screening focusing on rural populations aged above 55 - in terms of the number of new bacteriologically-positive pulmonary TB cases diagnosed and the cost of implementation assuming activities are conducted by the national TB program of Cambodia. We calculated the cost per additional case detected using the alternative ACF models.

RESULTS

Our analysis, which is the first of its kind for TB, revealed that the ACF model based on door to door screening in poor urban areas of Phnom Penh was the most cost-effective (249 USD per case detected, 737 cases diagnosed), followed by the model based on testing contacts of TB patients (308 USD per case detected, 807 cases diagnosed), and symptomatic screening of older rural populations (316 USD per case detected, 397 cases diagnosed).

CONCLUSIONS

Our study provides new evidence on the relative effectiveness and economics of three implementation models for enhanced TB case finding, in line with calls for data from 'routine conditions' to be included in disease control program strategic planning. Such cost-effectiveness comparisons are essential to inform resource allocation decisions of national policy makers in resource constraint settings. We applied a novel, pragmatic methodological approach, which was designed to provide results that are directly relevant to policy makers, costing the interventions from Cambodia's national TB program's perspective and using case finding data from implementation activities, rather than experimental settings.

Modeling the patient and health system impacts of alternative xpert® MTB/RIF algorithms for the diagnosis of pulmonary tuberculosis in Addis Ababa, Ethiopia

Background

To reduce global tuberculosis (TB) burden, the active disease must be diagnosed quickly and accurately and patients should be treated and cured. In Ethiopia, TB diagnosis mainly relies on spot-morning-spot (SMS) sputum sample smear analysis using Ziehl-Neelsen staining techniques (ZN). Since 2014 targeted use of xpert has been implemented. New diagnostic techniques have higher sensitivity and are likely to detect more cases if routinely implemented. The objective of our study was to project the effects of alternative diagnostic algorithms on the patient, health system, and costs, and identify cost-effective algorithms that increase TB case detection in Addis Ababa, Ethiopia.

Methods

An observational quantitative modeling framework was applied using the Virtual Implementation approach. The model was designed to represent the operational and epidemiological context of Addis Ababa, the capital city of Ethiopia. We compared eight diagnostic algorithm with ZN microscopy, light emitting diode (LED) fluorescence microscopy and Xpert MTB/RIF. Interventions with an annualized cost per averted disability adjusted life year (DALY) of less than the Gross Domestic Product (GDP) per capita are considered cost-effective interventions.

Results

With a cost lower than the average per-capita GDP (US$690 for Ethiopia) for each averted disability adjusted life year (DALY), three of the modeled algorithms are cost-effective. Implementing them would have important patient, health system, and population-level effects in the context of Addis Ababa

❖ The full roll-out of Xpert MTB/RIF as the primary test for all presumptive TB cases would avert 91170 DALYs (95% credible interval [CrI] 54888 – 127448) with an additional health system cost of US$ 11.6 million over the next 10 years. The incremental cost-effectiveness ratio (ICER) is $370 per DALY averted.

❖ Same day LED fluorescence microscopy for all presumptive TB cases combined with Xpert MTB/RIF targeted to HIV-positive and High multidrug resistant (MDR) risk groups would avert 73600 DALYs( 95% CrI 48373 - 99214) with an additional cost of US$5.1 million over the next 10 years. The ICER is $169per DALY averted.

❖ Same-day LED fluorescence microscopy for all presumptive TB cases (and no Xpert MTB/RIF) would avert 43580 DALYs with a reduction cost of US$ 0.2 million over the next 10years. The ICER is $13 per DALY averted.

Conclusions

The full roll-out of Xpert MTB/RIF is predicted to be the best option to substantially reduce the TB burden in Addis Ababa and is considered cost effective. However, the investment cost to implement this is far beyond the budget of the national TB control program. Targeted use of Xpert MTB/RIF for HIV positive and high MDR risk groups with same-day LED fluorescence microscopy for all other presumptive TB cases is an affordable alternative.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2417-6) contains supplementary material, which is available to authorized users.

The combined fixed-dose antituberculous drugs alter some reproductive functions with oxidative stress involvement in wistar rats

The reproductive toxicity of combined fixed-dose first-line antituberculosis (CFDAT) regimen was assessed in rats. Thirty-two (32) Wistar rats weighing 168.1 ± 8.0 g were divided into four groups of eight rats per group. Two groups of male and female rats were administered oral distilled water (1.6 ml) and CFDAT drugs containing rifampicin, isoniazid, pyrazinamide and ethambutol (RIPE, 92.5 mg/m2 per body surface area) respectively for forty-five days. Serum follicle stimulating hormone, luteinizing and testosterone were reduced significantly (p < 0.05) in the treated male rats. Similarly, sperm count levels were decreased by 27.3% when compared with control. RIPE elevated serum oestrogen (p < 0.05), progesterone (p < 0.05) as well as prolactin (p > 0.05) levels in the treated females. In addition, RIPE reduced (p < 0.05) total proteins levels and increased (p < 0.05, 53%) catalase levels in male but not female animals. Superoxide dismutase, glutathione-S-transferase, glutathione peroxidase, reduced glutathione levels as well as lipid peroxidation were unaltered in all rats respectively. Histopathological studies revealed congested peritesticular vessels and no changes in the ovary when compared with control. Overall, our results demonstrate reproductive toxicity potentials of RIPE in the rat, thus, suggesting that these reproductive parameters be monitored during antituberculous chemotherapy.

Developments in Impact Assessment of New Diagnostic Algorithms for Tuberculosis Control

A modified presentation of the impact assessment framework is proposed that improves accessibility while continuing to provide a checklist of the evidence needed to support policy decisions on the implementation of new tools for the diagnosis of tuberculosis.

Improving Control of Tuberculosis in Low-Burden Countries: Insights from Mathematical Modeling

Tuberculosis control and elimination remains a challenge for public health even in low-burden countries. New technology and novel approaches to case-finding, diagnosis, and treatment are causes for optimism but they need to be used cost-effectively. This in turn requires improved understanding of the epidemiology of TB and analysis of the effectiveness and cost-effectiveness of different interventions. We describe the contribution that mathematical modeling can make to understanding epidemiology and control of TB in different groups, guiding improved approaches to public health interventions. We emphasize that modeling is not a substitute for collecting data but rather is complementary to empirical research, helping determine what are the key questions to address to maximize the public-health impact of research, helping to plan studies, and making maximal use of available data, particularly from surveillance, and observational studies. We provide examples of how modeling and related empirical research inform policy and discuss how a combination of these approaches can be used to address current questions of key importance, including use of whole-genome sequencing, screening and treatment for latent infection, and combating drug resistance.

Point of care testing: Knowledge and utilization amongst Doctors in Government hospitals in Edo State, Nigeria

OBJECTIVE

The study assessed the knowledge and utilization of point of care testing (POCT) amongst doctors in two health facilities in Edo State, Nigeria.

METHODS

A descriptive cross-sectional study was carried out using a multistage sampling technique. Data were collected from 174 doctors in both centers using a 25 item structured questionnaire which was analyzed using SPSS version 20.0.

RESULT

The mean age of respondents was 31.26±2.14 years with 120 (69.0%) males and 54 (31.0%) females (male: female=2.2:1). Knowledge of POCT and utilization of POCT devices was good in 50.6% and 32.2% of respondents respectively. Utilization of POCT correlated significantly with knowledge of POCT (r=0.67, P<0.001) and availability of POCT devices (r=0.43, P<0.001). There was statistically significant association between utilization of POCT devices and Hospital (χ2=9.95, P=0.002); job designation (χ2=10.03, P=0.018) and availability of POCT devices (χ2=6.80, P=0.001). However, no statistically significant relationship was found between utilization of POCT devices and sex (χ2=0.23, P=0.629).

CONCLUSION

Promotion of POCT's utilization with regulation, training of doctors and establishment of regulatory framework/assessment teams will help improve healthcare services and achieve more beneficial outcomes. That way, POCT that is faster could be better.

Impact of Molecular Diagnostics for Tuberculosis on Patient-Important Outcomes: A Systematic Review of Study Methodologies

BACKGROUND

Several reviews on the accuracy of Tuberculosis (TB) Nucleic Acid Amplification Tests (NAATs) have been performed but the evidence on their impact on patient-important outcomes has not been systematically reviewed. Given the recent increase in research evaluating such outcomes and the growing list of TB NAATs that will reach the market over the coming years, there is a need to bring together the existing evidence on impact, rather than accuracy. We aimed to assess the approaches that have been employed to measure the impact of TB NAATs on patient-important outcomes in adults with possible pulmonary TB and/or drug-resistant TB.

METHODS

We first develop a conceptual framework to clarify through which mechanisms the improved technical performance of a novel TB test may lead to improved patient outcomes and outline which designs may be used to measure them. We then systematically review the literature on studies attempting to assess the impact of molecular TB diagnostics on such outcomes and provide a narrative synthesis of designs used, outcomes assessed and risk of bias across different study designs.

RESULTS

We found 25 eligible studies that assessed a wide range of outcomes and utilized a variety of experimental and observational study designs. Many potentially strong design options have never been used. We found that much of the available evidence on patient-important outcomes comes from a small number of settings with particular epidemiological and operational context and that confounding, time trends and incomplete outcome data receive insufficient attention.

CONCLUSIONS

A broader range of designs should be considered when designing studies to assess the impact of TB diagnostics on patient outcomes and more attention needs to be paid to the analysis as concerns about confounding and selection bias become relevant in addition to those on measurement that are of greatest concern in accuracy studies.

Comparing Tuberculosis Diagnostic Yield in Smear/Culture and Xpert® MTB/RIF-Based Algorithms Using a Non-Randomised Stepped-Wedge Design

Setting

Primary health services in Cape Town, South Africa.

Study Aim

To compare tuberculosis (TB) diagnostic yield in an existing smear/culture-based and a newly introduced Xpert^® MTB/RIF-based algorithm.

Methods

TB diagnostic yield (the proportion of presumptive TB cases with a laboratory diagnosis of TB) was assessed using a non-randomised stepped-wedge design as sites transitioned to the Xpert^® based algorithm. We identified the full sequence of sputum tests recorded in the electronic laboratory database for presumptive TB cases from 60 primary health sites during seven one-month time-points, six months apart. Differences in TB yield and temporal trends were estimated using a binomial regression model.

Results

TB yield was 20.9% (95% CI 19.9% to 22.0%) in the smear/culture-based algorithm compared to 17.9% (95%CI 16.4% to 19.5%) in the Xpert^® based algorithm. There was a decline in TB yield over time with a mean risk difference of -0.9% (95% CI -1.2% to -0.6%) (p<0.001) per time-point. When estimates were adjusted for the temporal trend, TB yield was 19.1% (95% CI 17.6% to 20.5%) in the smear/culture-based algorithm compared to 19.3% (95% CI 17.7% to 20.9%) in the Xpert^® based algorithm with a risk difference of 0.3% (95% CI -1.8% to 2.3%) (p = 0.796). Culture tests were undertaken for 35.5% of smear-negative compared to 17.9% of Xpert^® negative low MDR-TB risk cases and for 82.6% of smear-negative compared to 40.5% of Xpert^® negative high MDR-TB risk cases in respective algorithms.

Conclusion

Introduction of an Xpert^® based algorithm did not produce the expected increase in TB diagnostic yield. Studies are required to assess whether improving adherence to the Xpert^® negative algorithm for HIV-infected individuals will increase yield. In light of the high cost of Xpert^®, a review of its role as a screening test for all presumptive TB cases may be warranted.

Assessment of the patient, health system, and population effects of Xpert MTB/RIF and alternative diagnostics for tuberculosis in Tanzania: an integrated modelling approach

BACKGROUND

Several promising new diagnostic methods and algorithms for tuberculosis have been endorsed by WHO. National tuberculosis programmes now face the decision on which methods to implement and where to place them in the diagnostic algorithm.

METHODS

We used an integrated model to assess the effects of different algorithms of Xpert MTB/RIF and light-emitting diode (LED) fluorescence microscopy in Tanzania. To understand the effects of new diagnostics from the patient, health system, and population perspective, the model incorporated and linked a detailed operational component and a transmission component. The model was designed to represent the operational and epidemiological context of Tanzania and was used to compare the effects and cost-effectiveness of different diagnostic options.

FINDINGS

Among the diagnostic options considered, we identified three strategies as cost effective in Tanzania. Full scale-up of Xpert would have the greatest population-level effect with the highest incremental cost: 346 000 disability-adjusted life-years (DALYs) averted with an additional cost of US$36·9 million over 10 years. The incremental cost-effectiveness ratio (ICER) of Xpert scale-up ($169 per DALY averted, 95% credible interval [CrI] 104-265) is below the willingness-to-pay threshold ($599) for Tanzania. Same-day LED fluorescence microscopy is the next most effective strategy with an ICER of $45 (95% CrI 25-74), followed by LED fluorescence microscopy with an ICER of $29 (6-59). Compared with same-day LED fluorescence microscopy and Xpert full rollout, targeted use of Xpert in presumptive tuberculosis cases with HIV infection, either as an initial diagnostic test or as a follow-on test to microscopy, would produce DALY gains at a higher incremental cost and therefore is dominated in the context of Tanzania.

INTERPRETATION

For Tanzania, this integrated modelling approach predicts that full rollout of Xpert is a cost-effective option for tuberculosis diagnosis and has the potential to substantially reduce the national tuberculosis burden. It also estimates the substantial level of funding that will need to be mobilised to translate this into clinical practice. This approach could be adapted and replicated in other developing countries to inform rational health policy formulation.

Liquid vs Solid Culture Medium to Evaluate Proportion and Time to Change in Management of Suspects of Tuberculosis-A Pragmatic Randomized Trial in Secondary and Tertiary Health Care Units in Brazil

Background

The use of liquid medium (MGIT960) for tuberculosis (TB) diagnosis was recommended by WHO in 2007. However, there has been no evaluation of its effectiveness on clinically important outcomes.

Methods and Findings

A pragmatic trial was carried out in a tertiary hospital and a secondary health care unit in Rio de Janeiro City, Brazil. Participants were 16 years or older, suspected of having TB. They were excluded if only cerebral spinal fluid or blood specimens were available for analysis. MGIT960 technique was compared with the Lowenstein-Jensen (LJ) method for laboratory diagnosis of active TB. Primary outcome was the proportion of patients who had their initial medical management changed within 2 months after randomisation. Secondary outcomes were: mean time for changing the procedure, patient satisfaction with the overall treatment and adverse events. Data were analysed by intention-to-treat. Between April 2008 and September 2011, 693 patients were enrolled (348 to MGIT, 345 to LJ). Smear and culture results were positive for 10% and 15.7% of participants, respectively. Patients in the MGIT arm had their initial medical management changed more frequently than those in the LJ group (10.1% MGIT vs 3.8% LJ, RR 2.67 95% CI 1.44–.96, p = 0.002, NNT 16, 95% CI 10–39). Mean time for changing the initial procedure was greater in LJ group at both sites: 20.0 and 29.6 days in MGIT group and 52.2 and 64.3 in LJ group (MD 33.5, 95% CI 30.6–36.4, p = 0.0001). No other important differences were observed.

Conclusions

This study suggests that opting for the MGIT960 system for TB diagnosis provides a promising case management model for improving the quality of care and control of TB.

Trial Registration

Controlled-Trials.com ISRCTN79888843

Target product profile of a molecular drug-susceptibility test for use in microscopy centers

BACKGROUND

Current phenotypic testing for drug resistance in patients with tuberculosis is inadequate primarily with respect to turnaround time. Molecular tests hold the promise of an improved time to diagnosis.

METHODS

A target product profile for a molecular drug-susceptibility test (DST) was developed on the basis of a collaborative effort that included opinions gathered from researchers, clinicians, policy makers, and test developers on optimal clinical and operational characteristics in settings of intended use. In addition, the current diagnostic ecosystem and the diagnostic development landscape were mapped.

RESULTS

Molecular DSTs for detecting tuberculosis in microscopy centers should ideally evaluate for resistance to rifampin, fluoroquinolones, isoniazid, and pyrazinamide and enable the selection of the most appropriate treatment regimen. Performance characteristics of DSTs need to be optimized, but compromises can be made that depend on the trade-off between a false-positive result and a false-negative result. The operational requirements of a test will vary depending on the site of implementation. However, the most-important considerations pertain to quality control, maintenance and calibration, and the ability to export data.

CONCLUSION

This target product profile defines the needs as perceived by the tuberculosis stakeholder community and attempts to provide a means of communication with test developers to ensure that fit-for-purpose DSTs are being developed.

Defining the needs for next generation assays for tuberculosis

To accelerate the fight against tuberculosis, major diagnostic challenges need to be addressed urgently. Post-2015 targets are unlikely to be met without the use of novel diagnostics that are more accurate and can be used closer to where patients first seek care in affordable diagnostic algorithms. This article describes the efforts by the stakeholder community that led to the identification of the high-priority diagnostic needs in tuberculosis. Subsequently target product profiles for the high-priority diagnostic needs were developed and reviewed in a World Health Organization (WHO)-led consensus meeting. The high-priority diagnostic needs included (1) a sputum-based replacement test for smear-microscopy; (2) a non-sputum-based biomarker test for all forms of tuberculosis, ideally suitable for use at levels below microscopy centers; (3) a simple, low cost triage test for use by first-contact care providers as a rule-out test, ideally suitable for use by community health workers; and (4) a rapid drug susceptibility test for use at the microscopy center level. The developed target product profiles, along with complimentary work presented in this supplement, will help to facilitate the interaction between the tuberculosis community and the diagnostics industry with the goal to lead the way toward the post-2015 global tuberculosis targets.

Impact of replacing smear microscopy with Xpert MTB/RIF for diagnosing tuberculosis in Brazil: a stepped-wedge cluster-randomized trial

BACKGROUND

Abundant evidence on Xpert MTB/RIF accuracy for diagnosing tuberculosis (TB) and rifampicin resistance has been produced, yet there are few data on the population benefit of its programmatic use. We assessed whether the implementation of Xpert MTB/RIF in routine conditions would (1) increase the notification rate of laboratory-confirmed pulmonary TB to the national notification system and (2) reduce the time to TB treatment initiation (primary endpoints).

METHODS AND FINDINGS

We conducted a stepped-wedge cluster-randomized trial from 4 February to 4 October 2012 in 14 primary care laboratories in two Brazilian cities. Diagnostic specimens were included for 11,705 baseline (smear microscopy) and 12,522 intervention (Xpert MTB/RIF) patients presumed to have TB. Single-sputum-sample Xpert MTB/RIF replaced two-sputum-sample smear microscopy for routine diagnosis of pulmonary TB. In total, 1,137 (9.7%) tests in the baseline arm and 1,777 (14.2%) in the intervention arm were positive (p<0.001), resulting in an increased bacteriologically confirmed notification rate of 59% (95% CI = 31%, 88%). However, the overall notification rate did not increase (15%, 95% CI =  -6%, 37%), and we observed no change in the notification rate for those without a test result (-3%, 95% CI = -37%, 30%). Median time to treatment decreased from 11.4 d (interquartile range [IQR] = 8.5-14.5) to 8.1 d (IQR = 5.4-9.3) (p = 0.04), although not among confirmed cases (median 7.5 [IQR = 4.9-10.0] versus 7.3 [IQR = 3.4-9.0], p = 0.51). Prevalence of rifampicin resistance detected by Xpert was 3.3% (95% CI = 2.4%, 4.3%) among new patients and 7.4% (95% CI = 4.3%, 11.7%) among retreatment patients, with a 98% (95% CI = 87%, 99%) positive predictive value compared to phenotypic drug susceptibility testing. Missing data in the information systems may have biased our primary endpoints. However, sensitivity analyses assessing the effects of missing data did not affect our results.

CONCLUSIONS

Replacing smear microscopy with Xpert MTB/RIF in Brazil increased confirmation of pulmonary TB. An additional benefit was the accurate detection of rifampicin resistance. However, no increase on overall notification rates was observed, possibly because of high rates of empirical TB treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01363765. Please see later in the article for the Editors' Summary.

Clinical utility of a novel molecular assay in various combination strategies with existing methods for diagnosis of HIV-related tuberculosis in Uganda

BACKGROUND

Low income, high-tuberculosis burden, countries are considering selective deployment of Xpert MTB/RIF assay (Xpert) due to high cost per test. We compared the diagnostic gain of the Xpert add-on strategy with Xpert replacement strategy for pulmonary tuberculosis diagnosis among HIV-infected adults to inform its implementation.

METHODS

The first diagnostic sputum sample of 424 HIV-infected adults (67% with CD4 counts ≤200/mm3) suspected for tuberculosis was tested by direct Ziehl-Neelsen (DZN) and direct fluorescent microscopy (DFM); concentrated fluorescent microscopy (CFM); Lowenstein-Jensen (LJ) and Mycobacterial Growth Indicator Tube (MGIT) culture; and Xpert. Overall diagnostic yield and sensitivity were calculated using MGIT as reference comparator. The sensitivity of Xpert in an add-on strategy was calculated as the number of smear negative but Xpert positive participants among MGIT positive participants.

RESULTS

A total of 123 (29.0%) participants were MGIT culture positive for Mycobacterium tuberculosis. The sensitivity (95% confidence interval) was 31.7% (23.6-40.7%) for DZN, 35.0% (26.5-44.0%) for DFM, 43.9% (34.9-53.1%) for CFM, 76.4% (67.9-83.6) for Xpert and 81.3% (73.2-87.7%) for LJ culture. Add-on strategy Xpert showed an incremental sensitivity of 44.7% (35.7-53.9%) when added to DZN, 42.3% (33.4-51.5%) to DFM and 35.0% (26.5-44.0%) to CFM. This translated to an overall sensitivity of 76.4%, 77.3% and 79.0% for add-on strategies based on DZN, DFM and CFM, respectively, compared to 76.4% for Xpert done independently. From replacement to add-on strategy, the number of Xpert cartridges needed was reduced by approximately 10%.

CONCLUSIONS

Among HIV-infected TB suspects, doing smear microscopy prior to Xpert assay in add-on fashion only identifies a few additional TB cases.

A pragmatic approach to measuring, monitoring and evaluating interventions for improved tuberculosis case detection

The inability to detect all individuals with active tuberculosis has led to a growing interest in new approaches to improve case detection. Policy makers and program staff face important challenges measuring effectiveness of newly introduced interventions and reviewing feasibility of scaling-up successful approaches. While robust research will continue to be needed to document impact and influence policy, it may not always be feasible for all interventions and programmatic evidence is also critical to understand what can be expected in routine settings. The effects of interventions on early and improved tuberculosis detection can be documented through well-designed program evaluations. We present a pragmatic framework for evaluating and measuring the effect of improved case detection strategies using systematically collected intervention data in combination with routine tuberculosis notification data applying historical and contemporary controls. Standardized process evaluation and systematic documentation of program implementation design, cost and context will contribute to explaining observed levels of success and may help to identify conditions needed for success. Findings can then guide decisions on scale-up and replication in different target populations and settings.

Market assessment of tuberculosis diagnostics in Brazil in 2012

BACKGROUND

Improved diagnostics for the diagnosis of tuberculosis (TB) are urgently needed. However, test developers and investors require market size data to support new product development. This study assessed the served available market for TB diagnostics in Brazil in 2012 and the market segmentation in the public and private sectors.

METHODS

Data were collected on test volumes done in the public and private sectors for the diagnosis of latent and active TB, drug susceptibility testing and treatment follow-up. Tests included were tuberculin skin tests, interferon-gamma releases assays, smear microscopy, solid and liquid cultures, nucleic acid amplification tests and phenotypic drug susceptibility tests. The data were collected by means of an electronic survey via the Brazilian State laboratories and from sales information provided by manufacturers. Test costs for the public sector were calculated using a components approach, while costs for the private sector were based on prices paid by patients. The overall market value (expenditure) for the entire country was calculated using the public sector test costs.

RESULTS

During 2012, an estimated total of 2.4 million TB diagnostic tests were done in Brazil, resulting in an estimated overall market value of USD 17.2 million. The public sector accounted for 91% of the test volumes and 88% of the market value. Smear microscopy was the most commonly test (n = 1.3 million; 55% of total) at an estimated value of USD 3.7 million. Culture overall (n = 302,761) represented 13% of test volumes and 40% (USD 6.9 million) of the market value. On average, USD 208 was spent on TB diagnostics for every notified TB patient in Brazil, in 2012.

CONCLUSION

The TB diagnostics market value in Brazil in 2012 was over USD 17 million. These study results will help test developers to understand the current and potential market for replacement or add-on diagnostic technologies.

Economic challenges associated with tuberculosis diagnostic development

Tuberculosis remains a global health crisis in part due to underdiagnosis. Technological innovations are needed to improve diagnostic test accuracy and reduce the reliance on expensive laboratory infrastructure. However, there are significant economic challenges impeding the development and implementation of new diagnostics. The aim of this piece is to examine the current state of TB diagnostics, outline the unmet needs for new tests, and detail the economic challenges associated with development of new tests from the perspective of developers, policy makers and implementers.

Operational modelling to guide implementation and scale-up of diagnostic tests within the health system: exploring opportunities for parasitic disease diagnostics based on example application for tuberculosis

Research and innovation in the diagnosis of infectious and parasitic diseases has led to the development of several promising diagnostic tools, for example in malaria there is extensive literature concerning the use of rapid diagnostic tests. This means policymakers in many low and middle income countries need to make difficult decisions about which of the recommended tools and approaches to implement and scale-up. The test characteristics (e.g. sensitivity and specificity) of the tools alone are not a sufficient basis on which to make these decisions as policymakers need to also consider the best combination of tools, whether the new tools should complement or replace existing diagnostics and who should be tested. Diagnostic strategies need dovetailing to different epidemiology and structural resource constraints (e.g. existing diagnostic pathways, human resources and laboratory capacity). We propose operational modelling to assist with these complex decisions. Projections of patient, health system and cost impacts are essential and operational modelling of the relevant elements of the health system could provide these projections and support rational decisions. We demonstrate how the technique of operational modelling applied in the developing world to support decisions on diagnostics for tuberculosis, could in a parallel way, provide useful insights to support implementation of appropriate diagnostic innovations for parasitic diseases.

A user-friendly, open-source tool to project impact and cost of diagnostic tests for tuberculosis

Most models of infectious diseases, including tuberculosis (TB), do not provide results customized to local conditions. We created a dynamic transmission model to project TB incidence, TB mortality, multidrug-resistant (MDR) TB prevalence, and incremental costs over 5 years after scale-up of nine alternative diagnostic strategies. A corresponding web-based interface allows users to specify local costs and epidemiology. In settings with little capacity for up-front investment, same-day microscopy had the greatest impact on TB incidence and became cost-saving within 5 years if delivered at $10/test. With greater initial investment, population-level scale-up of Xpert MTB/RIF or microcolony-based culture often averted 10 times more TB cases than narrowly-targeted strategies, at minimal incremental long-term cost. Xpert for smear-positive TB had reasonable impact on MDR-TB incidence, but at substantial price and little impact on overall TB incidence and mortality. This user-friendly modeling framework improves decision-makers' ability to evaluate the local impact of TB diagnostic strategies.

DOI:http://dx.doi.org/10.7554/eLife.02565.001

Tuberculosis is an infectious bacterial disease caused predominantly by the microorganism Mycobacterium tuberculosis. Although the number of deaths from tuberculosis has been falling in recent years, the disease still kills more than 1 million people every year, mainly in developing countries. Tuberculosis can be treated with antibiotics, but the emergence of bacteria that are resistant to existing drugs is threatening efforts to eradicate the disease.

Preventing the spread of tuberculosis is heavily dependent on accurate diagnosis of individuals with the disease. This is challenging because the initial symptoms are often mild, usually just a cough, which means that someone can spread the disease to many others over a period of several months before the symptoms become worse—fever, night sweats, and weight loss—and they realize that they are sick. Multiple diagnostic strategies are available, from the relatively low-tech—examining sputum samples under a microscope to detect tuberculosis bacteria—to more sophisticated tests that can detect bacterial DNA and determine whether the bacteria are drug-resistant in less than 2 hr.

Choosing which diagnostic strategy to adopt can be challenging because the optimal solution in a region will depend on the specific local conditions. To overcome this problem, Dowdy et al. have developed a computer program that enables decision-makers to input four key parameters that describe the tuberculosis situation in their region, and to obtain 5-year projections of the rate of new infections, mortality, and total costs likely to result from adopting any of nine different diagnostic strategies.

The four parameters are the number of new cases of tuberculosis each year (incidence), the proportion of new cases that are multi-drug resistant, the proportion of the adult population that has HIV, and the local costs of various diagnostic techniques and treatments. Since the entire computer program is written in a freely available open-source programming language (Python), any user can tweak these parameters to provide a more precise fit to their own region. Alternatively, the standard version of the program can be run directly from a website without any need to interact with computer code.

This model is the first to enable local decision-makers to evaluate the impact of different diagnostic strategies for tuberculosis under the conditions specific to their region. The model predicts, for example, that in areas where there is little money available for up-front investment, same-day microscopy analysis of sputum samples and starting patients on treatment is the most cost-effective strategy for reducing the rate of new infections. Given the wide variation in conditions within even small geographical areas, this more flexible approach should lead to the more efficient use of resources and may, ultimately, help to reduce the spread of tuberculosis.

DOI:http://dx.doi.org/10.7554/eLife.02565.002

Community-based active tuberculosis case finding in poor urban settlements of Phnom Penh, Cambodia: a feasible and effective strategy

Background

In light of the limitations of the current case finding strategies and the global urgency to improve tuberculosis (TB) case-detection, a renewed interest in active case finding (ACF) has risen. The WHO calls for more evidence on innovative ways of TB screening, especially from low-income countries, to inform global guideline development. We aimed to assess the feasibility of community-based ACF for TB among the urban poor in Cambodia and determine its impact on case detection, treatment uptake and outcome.

Methods

Between 9/2/2012-31/3/2013 the Sihanouk Hospital Center of HOPE conducted a door-to-door survey for TB in deprived communities of Phnom Penh. TB workers and community health volunteers performed symptom screening, collected sputum and facilitated specimen transport to the laboratories. Fluorescence microscopy was introduced at three referral hospitals. The GeneXpert MTB/RIF assay (Xpert) was performed at tertiary level for individuals at increased risk of HIV-associated, drug-resistant or smear-negative TB. Mobile phone/short message system (SMS) was used for same-day issuing of positive results. TB workers contacted diagnosed patients and referred them for care at their local health centre.

Results

In 14 months, we screened 315.874 individuals; we identified 12.201 aged ≥15 years with symptoms suggestive of TB; 84% provided sputum. We diagnosed 783, including 737 bacteriologically confirmed, TB cases. Xpert testing yielded 41% and 48% additional diagnoses among presumptive HIV-associated and multidrug-resistant TB cases, respectively. The median time from sputum collection to notification (by SMS) of the first positive (microscopy or Xpert) result was 3 days (IQR 2–6). Over 94% commenced TB treatment and 81% successfully completed it.

Conclusion

Our findings suggest that among the urban poor ACF for TB, using a sensitive symptom screen followed by smear-microscopy and targeted Xpert, contributed to improved case detection of drug-susceptible and drug-resistant TB, shortening the diagnostic delay, and successfully bringing patients into care.

Tuberculosis screening in high human immunodeficiency virus prevalence settings: turning promise into reality

Twenty years of sky-high tuberculosis (TB) incidence rates and high TB mortality in high human immunodeficiency virus (HIV) prevalence countries have so far not been matched by the same magnitude or breadth of responses as seen in malaria or HIV programmes. Instead, recommendations have been narrowly focused on people presenting to health facilities for investigation of TB symptoms, or for HIV testing and care. However, despite the recent major investment and scale-up of TB and HIV services, undiagnosed TB remains highly prevalent at community level, implying that diagnosis of TB remains slow and incomplete. This maintains high transmission rates and exposes people living with HIV to high rates of morbidity and mortality. More intensive use of TB screening, with broader definitions of target populations, expanded indications for screening both inside and outside of health facilities, and appropriate selection of new diagnostic tools, offers the prospect of rapidly improving population-level control of TB. Diagnostic accuracy of suitable (high throughput) algorithms remains the major barrier to realising this goal. In the present study, we review the evidence available to guide expanded TB screening in HIV-prevalent settings, ideally through combined TB-HIV interventions that provide screening for both TB and HIV, and maximise entry to HIV and TB care and prevention. Ideally, we would systematically test, treat and prevent TB and HIV comprehensively, offering both TB and HIV screening to all health facility attendees, TB households and all adults in the highest risk communities. However, we are still held back by inadequate diagnostics, financing and paucity of population-impact data. Relevant contemporary research showing the high need for potential gains, and pitfalls from expanded and intensified TB screening in high HIV prevalence settings are discussed in this review.

Modeling the impact of alternative strategies for rapid molecular diagnosis of tuberculosis in Southeast Asia

Novel diagnostic tests hold promise for improving tuberculosis (TB) control, but their epidemiologic impact remains uncertain. Using data from the World Health Organization (2011-2012), we developed a transmission model to evaluate the deployment of 3 hypothetical TB diagnostic tests in Southeast Asia under idealized scenarios of implementation. We defined diagnostics by their sensitivity for smear-negative TB and proportion of patients testing positive who initiate therapy ("point-of-care amenability"), with tests of increasing point-of-care amenability having lower sensitivity. Implemented in the public sector (35% of care-seeking attempts), each novel test reduced TB incidence by 7%-9% (95% uncertainty range: 4%-13%) and mortality by 20%-22% (95% uncertainty range: 14%-27%) after 10 years. If also deployed in the private sector (65% of attempts), these tests reduced incidence by 13%-16%, whereas a perfect test (100% sensitivity and treatment initiation) reduced incidence by 20%. Annually detecting 20% of prevalent TB cases through targeted screening (70% smear-negative sensitivity, 85% treatment initiation) also reduced incidence by 19%. Sensitivity and point-of-care amenability are equally important considerations when developing novel diagnostic tests for TB. Novel diagnostics can substantially reduce TB incidence and mortality in Southeast Asia but are unlikely to transform TB control unless they are deployed actively and in the private sector.

Diagnostic point-of-care tests in resource-limited settings

The aim of diagnostic point-of-care testing is to minimise the time to obtain a test result, thereby allowing clinicians and patients to make a quick clinical decision. Because point-of-care tests are used in resource-limited settings, the benefits need to outweigh the costs. To optimise point-of-care testing in resource-limited settings, diagnostic tests need rigorous assessments focused on relevant clinical outcomes and operational costs, which differ from assessments of conventional diagnostic tests. We reviewed published studies on point-of-care testing in resource-limited settings, and found no clearly defined metric for the clinical usefulness of point-of-care testing. Therefore, we propose a framework for the assessment of point-of-care tests, and suggest and define the term test efficacy to describe the ability of a diagnostic test to support a clinical decision within its operational context. We also propose revised criteria for an ideal diagnostic point-of-care test in resource-limited settings. Through systematic assessments, comparisons between centralised testing and novel point-of-care technologies can be more formalised, and health officials can better establish which point-of-care technologies represent valuable additions to their clinical programmes.

Comparison of two methods for acquisition of sputum samples for diagnosis of suspected tuberculosis in smear-negative or sputum-scarce people: a randomised controlled trial

BACKGROUND

Sputum obtained either under instruction from a health-care worker or through induction can improve case detection of active tuberculosis. However, the best initial sputum sampling strategy for adults with suspected smear-negative or sputum-scarce tuberculosis in primary care is unclear. We compared these two methods of sample acquisition in such patients.

METHODS

In this randomised controlled trial, we enrolled adults (age ≥18 years) with sputum-scarce or smear-negative suspected tuberculosis from three primary care clinics in Cape Town, South Africa. Patients were randomly assigned (1:1) to receive either health-care worker instruction or induction to obtain sputum samples. Neither patients nor investigators were masked to allocation. The primary outcome was the proportion of patients who had started treatment after 8 weeks in a modified intention-to-treat population. Secondary outcomes were proportions starting treatment within different time periods, proportion of patients producing sputum for diagnosis, adverse effects, sputum samples' quality, and case detection by diagnostic method. This study is registered with ClinicalTrials.gov, number NCT01545661.

FINDINGS

We enrolled 481 patients, of whom 213 were assigned to health-care worker instruction versus 268 assigned to induction. The proportion of patients who started treatment in the 8 weeks after enrolment did not differ significantly between groups (53/213 [25%] vs 73/268 [27%]; OR 0·88, 95% CI 0·57-1·36; p=0·56). A higher proportion of instructed versus induced patients initiated empiric treatment based on clinical and radiography findings (32/53 [60%] vs 28/73 [38%]; p=0·015). An adequate sputum sample ≥1 mL was acquired in a lower proportion of instructed versus induced patients (164/213 [77%] vs 238/268 [89%]; p<0·0001), and culture-based diagnostic yield was lower in instructed versus induced patients (24/213 [11%] vs 51/268 [19%]; p=0·020). However, same-day tuberculosis case detection was similar in both groups using either smear microscopy (13/213 [6%] vs 22/268 [8%]; p=0·38) or Xpert-MTB/RIF assay (13/89 [15%] vs 20/138 [14%]; p=0·98). No serious adverse events occurred in either group; side-effects related to sample acquisition were reported in 32 of 268 (12%) patients who had sputum induction and none who had instruction. Cost per procedure was lower for instructed than for induced patients (US$2·14 vs US$7·88).

INTERPRETATION

Although induction provides an adequate sample and a bacteriological diagnosis more frequently than instruction by a health-care worker, it is more costly, does not result in a higher proportion of same-day diagnoses, and-because of widespread empiric treatment-may not result in more patients starting treatment. Thus, health-care worker instruction might be the preferred strategy for initial collection of sputum samples in adults with suspected sputum-scarce or smear-negative tuberculosis in a high burden primary care setting.

FUNDING

South African National Research Foundation, European Commission, National Institutes of Health, European and Developing Countries Clinical Trials Partnership, Discovery Foundation.

Point-of-care testing and the control of infectious diseases

Point-of-care tests (POCTs) play an important role in bridging the gap between centralized laboratory diagnostics and peripheral healthcare service providers. Particularly in infectious diseases such as HIV/AIDS and TB where early detection is imperative to improve disease outcome, uptake of an accurate test that is simple, rapid and robust can significantly alter the epidemiology and control of the disease. However, a good POCT can only serve its full potential when adopted in a comprehensive programmatic context linking patients to on-site case management. Immunochromatographic lateral flow devices for detection of antibody or antigen currently dominate available POCTs, and development of such devices has relied on the discovery and optimization of definitive biomarkers suitable for such platforms. In the future, however, there will be an increasing need to develop cost-effective POCTs that address biomarkers that are well established in laboratory settings but are not currently amenable to point-of-care, such as molecular tests for drug resistance in TB and viral load in HIV and viral hepatitis.

Alignment of new tuberculosis drug regimens and drug susceptibility testing: a framework for action

New tuberculosis drug regimens are creating new priorities for drug susceptibility testing (DST) and surveillance. To minimise turnaround time, rapid DST will need to be prioritised, but developers of these assays will need better data about the molecular mechanisms of resistance. Efforts are underway to link mutations with drug resistance and to develop strain collections to enable assessment of new diagnostic assays. In resource-limited settings, DST might not be appropriate for all patients with tuberculosis. Surveillance data and modelling will help country stakeholders to design appropriate DST algorithms and to decide whether to change drug regimens. Finally, development of practical DST assays is needed so that, in countries where surveillance and modelling show that DST is advisable, these assays can be used to guide clinical decisions for individual patients. If combined judiciously during both development and implementation, new tuberculosis regimens and new DST assays have enormous potential to improve patient outcomes and reduce the burden of disease.

Factors associated with the rapid implementation process of the fixed-dose combination RHZE tuberculosis regimen in Brazil: an ecological study

BACKGROUND

The Brazilian National Tuberculosis Control Program (NTCP) recommended the fixed-dose four-drug combination (FDC-RHZE) regimen to treat new tuberculosis cases in December 2009, expecting to increase adherence and avoid resistance. We evaluated factors associated with the speed of the new regimen implementation process in this continent-sized country.

METHODS

We conducted an ecological study based on the Brazilian Case Notification Database (SINAN) having the Brazilian municipalities as the analytical unit. Municipalities with at least one case reported from December 2009 to March 2011 were considered eligible. The association of rapid (≤ 3 months) implementation of the new regimen with demographic, epidemiological and operational health service characteristics, such as compliance with NTCP recommendations (supervised treatment, bacteriological confirmation of the diagnosis and monthly bacteriological monitoring), was analyzed. We used the adjusted odds ratios (OR) and their 95% confidence interval (CI) to assess the association of independent variables with the outcome in a multiple logistic regression model.

RESULTS

Rapid implementation of the new regimen in municipalities was associated with small populations (OR=25.5, 95% CI= 19.1-34.1), low population density (OR=2.3, 95% CI= 1.9-2.9), low tuberculosis incidence rates (OR=8.8, 95% CI= 6.7-11.4) and good compliance with other NTCP recommendations.

CONCLUSIONS

We showed that SINAN secondary data analysis is feasible and useful to learn lessons from. Municipalities with high tuberculosis burden and large populations need special attention for implementing new recommendations. This is particularly important considering the Global Alliance pipeline for new tuberculosis treatment regimens.

Can Brazil play a more important role in global tuberculosis drug production? An assessment of current capacity and challenges

BACKGROUND

Despite the existence of effective treatment, tuberculosis is still a global public health issue. The World Health Organization recommends a six-month four-drug regimen in fixed-dose combination formulation to treat drug sensitive tuberculosis, and long course regimens with several second-line drugs to treat multi-drug resistant tuberculosis. To achieve the projected tuberculosis elimination goal by 2050, it will be essential to ensure a non-interrupted supply of quality-assured tuberculosis drugs. However, quality and affordable tuberculosis drug supply is still a significant challenge for National Tuberculosis Programs.

DISCUSSION

Quality drug production requires a combination of complex steps. The first challenge is to guarantee the quality of tuberculosis active pharmaceutical ingredients, then ensure an adequate manufacturing process, according to international standards, to guarantee final product's safety, efficacy and quality. Good practices for storage, transport, distribution and quality control procedures must follow. In contrast to other high-burden countries, Brazil produces tuberculosis drugs through a strong network of public sector drug manufacturers regulated by a World Health Organization-certified national sanitary authority. The installed capacity for production surpasses the 71,000 needed treatments in the country. However, in order to be prepared to act as a global supplier, important bottlenecks are to be overcome. This article presents an in-depth analysis of the current status of production of tuberculosis drugs in Brazil and the bottlenecks and opportunities for the country to sustain national demand and play a role as a potential global supplier. Raw material and drug production, quality control, international certification and pre-qualification, political commitment and regulatory aspects are discussed, as well recommendations for tackling these bottlenecks. This discussion becomes more important as new drugs and regimens to treat tuberculosis are expected in a close future.

SUMMARY

International manufacturers of raw material for tuberculosis treatment should undergo certification and pre-qualify their active pharmaceutical ingredients as a first step to ensure quality of tuberculosis drugs. At the country level, Brazilian public manufacturers should apply for international certification and tuberculosis drugs should be pre-qualified by international organisms. Finally, only with political commitment and large-scale production will Brazilian public sector manufacturers be able to partially supply the global market.

Prospects for tuberculosis elimination

The target for TB elimination is to reduce annual incidence to less than one case per million population by 2050. Meeting that target requires a 1,000-fold reduction in incidence in little more than 35 years. This can be achieved only by combining the effective treatment of active TB-early case detection and high cure rates to interrupt transmission-with methods to prevent new infections and to neutralize existing latent infections. Vigorous implementation of the WHO Stop TB Strategy is needed to achieve the former, facilitated by the effective supply of, and demand for, health services. The latter calls for new technology, including biomarkers of TB risk, diagnostics, drugs, and vaccines. An important milestone en route to elimination will be reached when there is less than 1 TB death per 100,000 population, marking entry into the elimination phase. This landmark can be reached by many countries within 1-2 decades.

Promise versus reality: optimism bias in package inserts for tuberculosis diagnostics

Laboratorians and clinicians often rely on package inserts of diagnostic tests to assess their accuracy. We compared test accuracy for tuberculosis diagnostics reported in 19 package inserts against estimates in published meta-analyses and found that package inserts generally report overoptimistic accuracy estimates. However, package inserts of most tests approved by the U.S. Food and Drug Administration (FDA) or endorsed by the World Health Organization provide more realistic estimates that agree with meta-analyses.

Point-of-care testing for infectious diseases: diversity, complexity, and barriers in low- and middle-income countries

Madhukar Pai and colleagues discuss a framework for envisioning how point-of-care testing can be applied to infectious diseases in low- and middle-income countries.