Cost-effectiveness of Quantiferon®-TB Gold-in-Tube versus tuberculin skin testing for contact screening and treatment of latent tuberculosis infection in Brazil

Systematic review of the economic impact of novel Mycobacterium tuberculosis specific antigen-based skin tests for detection of TB infection compared with tuberculin skin test and interferon-gamma release assays

The Purified Protein Derivative tuberculin skin tests (TST) and blood-based Mycobacterium tuberculosis (M.tb) specific interferon-gamma release assays (IGRA) are the currently used tests for identifying individuals with TB infection for preventive treatment. However, challenges around access and implementation have limited their use. Novel M.tb specific skin tests (TBST) such as Diaskintest, ESAT6-CFP10 (C-TST), C-Tb (also known as Cy-Tb), and DPPD may provide accurate and scalable options but evidence synthesis on their economic impact is lacking. We conducted two separate systematic reviews to compare the costs and cost-effectiveness of (1) the novel skin tests TBST (primary), and (2) TST and IGRA tests (secondary), to support WHO guideline development. We searched for articles presenting economic evaluations of the diagnostic tests using a health provider perspective and related to TB infection in humans. We considered papers written in English, Chinese or Russian. In the primary review, eight studies for novel TBST were found. One study in Brazil assessed cost-effectiveness of C-TST and Diaskintest and seven in Russia assessed the Diaskintest, while none evaluated C-Tb or DPPD. The review showed on average, Diaskintest kit costs (in 2021 USD) $1.60 (1.50 - 1.70), while full unit costs were estimated at $5.07. C-TST unit cost was $9.96. The second review found 32 articles on IGRA and/or the TST. These presented an average TST full unit cost of $37.88, and $87.81 for IGRA. Studies' quality for TBST was limited while high-quality studies were found for TST and IGRA tests. In conclusion, there is limited evidence regarding the costs and cost-effectiveness of novel TBST. Conversely, there is substantial evidence for TST and IGRA tests, but most studies were performed in high-income and low-TB burden settings and their cost-effectiveness varied between and within risk groups without clear economic consensus.

Cost-effectiveness and health impact of screening and treatment of Mycobacterium tuberculosis infection among formerly incarcerated individuals in Brazil: a Markov modelling study

BACKGROUND

Individuals who were formerly incarcerated have high tuberculosis incidence, but are generally not considered among the risk groups eligible for tuberculosis prevention. We investigated the potential health impact and cost-effectiveness of Mycobacterium tuberculosis infection screening and tuberculosis preventive treatment (TPT) for individuals who were formerly incarcerated in Brazil.

METHODS

Using published evidence for Brazil, we constructed a Markov state transition model estimating tuberculosis-related health outcomes and costs among individuals who were formerly incarcerated, by simulating transitions between health states over time. The analysis compared tuberculosis infection screening and TPT, to no screening, considering a combination of M tuberculosis infection tests and TPT regimens. We quantified health effects as reductions in tuberculosis cases, tuberculosis deaths, and disability-adjusted life-years (DALYs). We assessed costs from a tuberculosis programme perspective. We report intervention cost-effectiveness as the incremental costs per DALY averted, and tested how results changed across subgroups of the target population.

FINDINGS

Compared with no intervention, an intervention incorporating tuberculin skin testing and treatment with 3 months of isoniazid and rifapentine would avert 31 (95% uncertainty interval 14-56) lifetime tuberculosis cases and 4·1 (1·4-5·8) lifetime tuberculosis deaths per 1000 individuals, and cost US$242 per DALY averted. All test and regimen combinations were cost-effective compared with no screening. Younger age, longer incarceration, and more recent prison release were each associated with significantly greater health benefits and more favourable cost-effectiveness ratios, although the intervention was cost-effective for all subgroups examined.

INTERPRETATION

M tuberculosis infection screening and TPT for individuals who were formerly incarcerated appears cost-effective, and would provide valuable health gains.

FUNDING

National Institutes of Health.

TRANSLATION

For the Portuguese translation of the abstract see Supplementary Materials section.

Economic evaluation of diagnosis and treatment for latent tuberculosis infection among contacts of pulmonary tuberculosis patients in Thailand

Currently, interferon-gamma release assay (IGRA) is costly and not included as latent tuberculosis infection (LTBI) screening test strategy in Thailand's Universal Coverage Scheme (UCS) benefit package. The objective of this study was to assess the cost-utility of LTBI screening strategies among tuberculosis (TB) contacts in Thailand. A hybrid decision tree and Markov model was developed to compare the lifetime costs and health outcomes of tuberculin skin test (TST) and IGRA, in comparison to no screening, based on a societal perspective. Health outcomes were the total number of TB cases averted and quality-adjusted life years (QALYs), with results presented as an incremental cost-effectiveness ratio (ICER). One-way and probabilistic sensitivity analyses were performed to explore uncertainties in all parameters. The ICER of TST compared with no screening was 27,645 baht per QALY gained, while that of IGRA compared to TST was 851,030 baht per QALY gained. In a cohort of 1000 TB contacts, both TST and IGRA strategies could avert 282 and 283 TB cases, respectively. At the Thai societal willingness-to-pay threshold of 160,000 baht per QALY gained, TST was deemed cost-effective, whereas IGRA would not be cost-effective, unless the cost of IGRA was reduced to 1,434 baht per test.

Simulation-based economic evaluation of the Wolbachia method in Brazil: a cost-effective strategy for dengue control

Background

Dengue virus (DENV) is an arbovirus transmitted by Aedes aegypti mosquitoes, which can cause severe conditions such as hemorrhagic fever and dengue shock syndrome. These conditions are associated with adverse social, clinical, and economic consequences in Brazil. Herein, the Wolbachia mosquito replacement method is a promising dengue control strategy.

Methods

We estimated the economic impact of implementing the Wolbachia mosquito replacement method in seven Brazilian cities. A mathematical microsimulation model tracked nearly 23 million inhabitants over a 20-year period, considering the transitions between five different health states (susceptible, inapparent, outpatient, hospitalised and death). Direct costs included local dengue control programs, Wolbachia implementation and dengue care. Indirect costs related to death and productivity loss, as well as disability-adjusted life-years (DALY) averted were also considered.

Findings

Without Wolbachia, the model projected 1,762,688 reported dengue cases over 20 years. Implementing the Wolbachia method would avert at least 1,295,566 dengue cases, resulting in lower costs and greater effectiveness in all simulated cities. On average, for every 1000 inhabitants followed for 20 years, the Wolbachia method yielded a cost difference of USD 538,233.68 (BRL 2,691,168.40) and averted 5.56 DALYs. Net monetary benefits (NMB) were positive in all seven cities, ranging from USD 110.72 (BRL 553.59) to USD 1399.19 (BRL 6995.95) per inhabitant. Alternative scenarios have also shown a favourable return on investment with a positive benefit-cost ratio (BCR).

Interpretation

Wolbachia is likely a cost-effective strategy in the Brazilian context, consistent with international studies. Sensitivity analysis and alternative scenarios confirmed the robustness of the results.

Funding

This study was funded by the Wellcome Trust under a grant (224459/Z/21/Z).

Cost-Effectiveness Analysis Comparing QuantiFERON-TB Gold Plus Test and Tuberculin Skin Test for the Diagnosis of Latent Tuberculosis Infection in Immunocompetent Subjects in Colombia

OBJECTIVES

To determine the cost-effectiveness of the QuantiFERON-TB Gold Plus (QFT-Plus) test versus the tuberculin skin test in diagnosing latent tuberculosis infection in immunocompetent subjects in the context of the Colombian healthcare system.

METHODS

A hypothetical cohort of 2000 immunocompetent adults vaccinated with Bacillus Calmette-Guérin at birth who are asymptomatic for tuberculosis disease was simulated and included in a decision tree over a horizon of <1 year. The direct healthcare costs related to tests, antituberculosis treatment, and medical care were considered, and diagnostic performance was used as a measure of effectiveness. The incremental cost-effectiveness ratio (ICER) was estimated, and univariate deterministic and probabilistic sensitivity analyses were carried out using 5000 simulations. The currency was the US dollar for the year 2022, with a cost-effectiveness threshold of $6666 USD (1 gross domestic product per capita for 2022).

RESULTS

QFT-Plus was cost-effective with an ICER of $5687 USD for each correctly diagnosed case relative to a threshold of $6666 USD. In the deterministic analysis, QFT-Plus was cost-effective in half of the proposed scenarios. The variable that most affected the ICER was the prevalence of latent tuberculosis and test sensitivities. In the probabilistic analysis, QFT-Plus was cost-effective in 54.74% of the simulated scenarios, and tuberculin skin test was dominant in 13.84%.

CONCLUSIONS

The study provides evidence of the cost-effectiveness of QFT-Plus compared with the tuberculin skin test in diagnosing latent tuberculosis infection in immunocompetent adults in the Colombian context.

Economic evaluation of novel Mycobacterium tuberculosis specific antigen-based skin tests for detection of TB infection: A modelling study

Evidence on the economic impact of novel skin tests for tuberculosis infection (TBST) is scarce and limited by study quality. We used estimates on the cost-effectiveness of the use of TBST compared to current tuberculosis infection (TBI) tests to assess whether TBST are affordable and feasible to implement under different country contexts. A Markov model parametrised to Brazil, South Africa and the UK was developed to compare the cost-effectiveness of three TBI testing strategies: (1) Diaskintest (DST), (2) TST test, and (3) IGRA QFT test. Univariate and probabilistic sensitivity analyses over unit costs and main parameters were performed. Our modelling results show that Diaskintest saves $5.60 and gains 0.024 QALYs per patient and $8.40, and 0.01 QALYs per patient in Brazil, compared to TST and IGRA respectively. In South Africa, Diaskintest is also cost-saving at $4.39, with 0.015 QALYs per patient gained, compared to TST, and $64.41, and 0.007 QALYs per patient, compared to IGRA. In the UK, Diaskintest saves $73.33, and gaines 0.0351 QALYs per patient, compared to TST. However, Diaskintest, compared to IGRA, showed an incremental cost of $521.45 (95% CI (500.94-545.07)) per QALY, below the willingness-to-pay threshold of $20.223 per QALY. Diaskintest potentially saves costs and results in greater health gains than the TST and IGRA tests in Brazil and South Africa. In the UK Diaskintest would gain health but also be more costly. Our results have potential external validity because TBST remained cost-effective despite extensive sensitivity analyses.

A costing framework to compare tuberculosis infection tests

OBJECTIVE

To develop a framework to estimate the practical costs incurred from, and programmatic impact related to, tuberculosis (TB) infection testing-tuberculin skin tests (TST) versus interferon gamma release assay (IGRA)-in a densely populated high-burden TB area.

METHODS

We developed a seven-step framework that can be tailored to individual TB programmes seeking to compare TB infection (TBI) diagnostics to inform decision-making. We present methodology to estimate (1) the prevalence of TBI, (2) true and false positives and negatives for each test, (3) the cost of test administration, (4) the cost of false negatives, (5) the cost of treating all that test positive, (6) the per-test cost incurred due to treatment and misdiagnosis and (7) the threshold at which laboratory infrastructure investments for IGRA are outweighed by system-wide savings incurred due to IGRA utilisation. We then applied this framework in a densely populated, peri-urban district in Lima, Peru with high rates of Bacillus Calmette-Guérin (BCG) vaccination.

FINDINGS

The lower sensitivity of TST compared with IGRA is a major cost driver, leading to health system and societal costs due to misdiagnosis. Additionally, patient and staff productivity costs were greater for TST because it requires two patient visits compared with only one for IGRA testing. When the framework was applied to the Lima setting, we estimate that IGRA-associated benefits outweigh infrastructural costs after performing 672 tests.

CONCLUSIONS

Given global shortages of TST and concerns about costs of IGRA testing and laboratory capacity building, this costing framework can provide public health officials and TB programmes guidance for decision-making about TBI testing locally. This framework was designed to be adaptable for use in different settings with available data. Diagnostics that increase accuracy or mitigate time to treatment should be thought of as an investment instead of an expenditure.

The Global Expansion of LTBI Screening and Treatment Programs: Exploring Gaps in the Supporting Economic Evidence

The global burden of latent TB infection (LTBI) and the progression of LTBI to active TB disease are important drivers of ongoing TB incidence. Addressing LTBI through screening and TB preventive treatment (TPT) is critical in order to end the TB epidemic by 2035. Given the limited resources available to health ministries around the world in the fight against TB, we must consider economic evidence for LTBI screening and treatment strategies to ensure that limited resources are used to achieve the biggest health impact. In this narrative review, we explore key economic evidence around LTBI screening and TPT strategies in different populations to summarize our current understanding and highlight gaps in existing knowledge. When considering economic evidence supporting LTBI screening or evaluating different testing approaches, a disproportionate number of economic studies have been conducted in high-income countries (HICs), despite the vast majority of TB burden being borne in low- and middle-income countries (LMICs). Recent years have seen a temporal shift, with increasing data from low- and middle-income countries (LMICs), particularly with regard to targeting high-risk groups for TB prevention. While LTBI screening and prevention programs can come with extensive costs, targeting LTBI screening among high-risk populations, such as people living with HIV (PLHIV), children, household contacts (HHC) and immigrants from high-TB-burden countries, has been shown to consistently improve the cost effectiveness of screening programs. Further, the cost effectiveness of different LTBI screening algorithms and diagnostic approaches varies widely across settings, leading to different national TB screening policies. Novel shortened regimens for TPT have also consistently been shown to be cost effective across a range of settings. These economic evaluations highlight key implementation considerations such as the critical nature of ensuring high rates of adherence and completion, despite the costs associated with adherence programs not being routinely assessed and included. Digital and other adherence support approaches are now being assessed for their utility and cost effectiveness in conjunction with novel shortened TPT regimens, but more economic evidence is needed to understand the potential cost savings, particularly in settings where directly observed preventive therapy (DOPT) is routinely conducted. Despite the growth of the economic evidence base for LTBI screening and TPT recently, there are still significant gaps in the economic evidence around the scale-up and implementation of expanded LTBI screening and treatment programs, particularly among traditionally hard-to-reach populations.

Economic Evaluation of Screening Strategy for Latent Tuberculosis Infection (LTBI) in Contacts of Tuberculosis Patients: Systematic Review and Quality Assessment

A tuberculin skin test (TST) or interferon-gamma release assay (IGRA) can be used to screen for latent tuberculosis infection (LTBI). Due to its low cost, TST has been used particularly in underdeveloped countries. The limitations of TST were poor specificity in populations with a high prevalence of Bacille Calmette-Guérin (BCG) vaccination and variability of test readers. IGRA is used as an alternative to TST in settings where higher costs can be supported. The lack of studies conducted in high TB incidence countries since previous review, and using relevant assessment tools of the quality appraisal make the need for updated studies and a more comprehensive systematic review. This study aimed to conduct a systematic review of published economic evaluations of screening strategies for LTBI in contacts of TB patients, assess the quality of these studies, and compare the assessment results related to a country's income level in order to provide information to other countries. The databases were searched in January 2022 including MEDLINE and Scopus. Two independent reviewers evaluated the included studies based on eligibility criteria, data extraction, and quality assessment. Eleven economic evaluations of LTBI diagnostic tests in TB contacts were included. Most studies were conducted in high-income countries (91%) and used cost-effectiveness analysis methods (73%). The quality assessment of reporting and data sources was appropriate, ranging from 71% to 89%. Interventions varied from study to study. The outcomes were cost per life years gained (27%), cost per quality-adjusted life year gained (27%), cost per TB case prevented (36%), and cost per close contact case (10%). In high-income countries which were not countries with high TB burden, the use of IGRA alone for screening TB contacts was cost-effective, whereas TST was cost-effective in only two studies. In comparison to TST, IGRA could reduce false-positive results, resulting in fewer patients undergoing TB treatment and preventive treatment.

The economic burden of congenital Zika Syndrome in Brazil: an overview at 5 years and 10 years

Background

The aim of this paper is to estimate the economic burden of children with congenital Zika Syndrome (CZS) in Brazil over 5–10 years.

Methods

We conducted a modelling study based on data collected in a case–control study in Brazil, including children with CZS (cases) and typically developing children (controls), born in 2015 and 2016. In total, 484 participants were recruited in two sites, Recife and Rio de Janeiro. Social and economic information was collected in a survey from the carers of cases and controls, and detailed healthcare utilisation was recorded for each child in the Rio de Janeiro cohort prospectively in a database. We used this information to estimate the cost per child with severe, moderate and no CZS and incremental cost per child with severe and moderate versus no CZS from a disaggregated societal perspective. These estimates were incorporated into an economic burden model to estimate the incremental burden of the CZS epidemic in Brazil over 5 years and 10 years.

Findings

The societal cost per child with severe CZS was US$50 523 to 10 years of age (born in 2015 and 2016), substantially higher than the costs for moderate CZS (US$29 283) and without CZS (US$12 331). The incremental economic burden of severe versus no CZS in Brazil over 10 years was US$69.4 million from the household and US$129.0 million from the government perspective. For moderate CZS, these figures amounted to US$204.1 million and US$86.6 million. Over 10 years, 97% of the total societal economic cost of severe CZS is borne by the government, but only 46% for moderate CZS.

Interpretation

The economic burden of CZS is high at the household, provider and government levels. The compensatory government payments helped to alleviate some of the additional costs incurred by families with a child qualifying for the disability benefits, and could be scaled to include the children with moderate CZS.

Scaling up investigation and treatment of household contacts of tuberculosis patients in Brazil: a cost-effectiveness and budget impact analysis

Background

In Brazil, investigation and treatment of tuberculosis infection (TBI) in households contacts (HHC) of TB patients is not a priority. We estimated the cost-effectiveness and budget-impact of scaling-up an enhanced HHC management in Brazil.

Methods

We conceptualized a cascade-of-care that captures how HHC of tuberculosis patients are investigated in Brazil (status quo) and two enhanced strategies for management of HHC focusing on: (1) only tuberculosis disease (TBD) detection and, (2) TBD and TBI detection and treatment. Effectiveness was the number of HHC diagnosed with TBD and completing TBI treatment. Proportions in the cascades-of-care were derived from a meta-analysis. Health-system costs (2019 US$) were based on literature and official data from Brazil. The impact of enhanced strategies was extrapolated using reported data from 2019.

Findings

With the status quo, 0 (95% uncertainty interval: 0-1) HHC are diagnosed with TBD and 2 (0-16) complete TBI treatment. With strategy(1), an additional 15 (3-45) HHC would be diagnosed with TBD at a cost of US$346 each. With strategy(2), 81 (19-226) additional HHC would complete TBI treatment at a cost of US$84 each. A combined strategy, implemented nationally to enhance TBD detection and TBI treatment would result in an additional 9,711 (845-28,693) TBD being detected, and 51,277 (12,028-143,495) more HHC completing TBI treatment each year, utilizing 10.9% and 11.6% of the annual national tuberculosis program budget, respectively.

Interpretation

Enhanced detection and treatment of TBD and TBI among HHC in Brazil can be achieved at a national level using current tools at reasonable cost.

Funding

None.

Comparing the cost-effectiveness of two screening strategies for latent tuberculosis infection in Portugal

INTRODUCTION AND OBJECTIVES

Screening for latent tuberculosis infection (LTBI) in close contacts of infectious TB cases might include Tuberculin Skin Test (TST) and Interferon-Gamma Release Assays (IGRA), in combination or as single-tests. In Portugal, the screening strategy changed from TST followed by IGRA to IGRA-only testing in 2016. Our objective was to compare the cost-effectiveness of two-step TST/IGRA with the current IGRA-only screening strategy in immunocompetent individuals exposed to individuals with respiratory TB.

MATERIALS AND METHODS

We reviewed clinical records of individuals exposed to infectious TB cases diagnosed in 2015 and 2016, in two TB outpatient centers in the district of Porto. We estimated medical, non-medical and indirect costs for each screening strategy, taking into account costs of tests and health care personnel, travel distance from place of residence to screening site and employment status. We calculated the incremental cost-effectiveness ratio (ICER) as the cost difference between the two screening strategies with the difference number of LTBI diagnosis as a measure of cost-effectiveness, assuming that treating LTBI is a cost-effective intervention. We also calculated adjusted odds-ratios to test the association between diagnosis of LTBI and screening strategy and estimated the total cost for averting a potential TB case.

RESULTS

We compared 499 contacts TST/IGRA screened with 547 IGRA-only. IGRA-only strategy yielded a higher screening effectiveness for diagnosing latent tuberculosis infection (aOR 2.12, 95%CI: 1.53 - 2.94). ICER was €106 per LTBI diagnosis, representing increased effectiveness with a slightly increased cost of IGRA-only screening strategy.

CONCLUSIONS

Our data suggests that in Portugal LTBI screening with IGRA-only is more cost-effective than the two-step TST/IGRA testing strategy, preventing a higher number of cases of TB cases.

Specificity of tuberculin skin test improved by BCG immunization schedule change in Japan

INTRODUCTION

Tuberculin skin test (TST) has been used to diagnose tuberculosis (TB) and latent tuberculosis infection (LTBI). However, in Bacillus Calmette-Guérin (BCG) vaccinated patients, TST tends to produce false-positive results. According to the previous vaccination schedule, Japanese people were mandated to receive up to three doses of BCG-vaccine. The vaccination schedule was changed in 2003 and as per the new schedule, only infants are administered a dose of BCG vaccine. Our hypothesis is that this change can lead to a reduction in the cross-reaction to TST.

METHODS

We evaluated the TST results obtained from 1097 recruits from six defense camps and 667 recruits from an air base. These TST data were divided into two groups according to the date of birth: a new group and an old group according to the BCG immunization schedule. We then analyzed positive and negative reaction of TST and erythema sizes.

RESULTS

We confirmed that the change in BCG-vaccination schedule significantly decreased TST false-positive reaction (P_meta = 1.4 × 10^-18; risk ratio = 0.83; 95% confidence interval: 0.80-0.87) and erythema size (P_meta = 1.1 × 10^-4; mean difference = 6.6 mm; 95% confidence interval: 3.2 mm-9.9 mm).

CONCLUSIONS

We showed the reduction in BCG cross-reaction to TST, in the new BCG vaccination schedule group, compared to the old group, we also have extracted information on the improvement in the specificity of TST for LTBI and TB diagnosis, which resulted from BCG schedule change.

Cost-effectiveness of a Pharmacogenomic Test for Stratified Isoniazid Dosing in Treatment of Active Tuberculosis

Background

There is marked interindividual variability in metabolism and resulting toxicity and effectiveness of drugs used for tuberculosis treatment. For isoniazid, mutations in the N-acetyltransferase 2 (NAT2) gene explain >88% of pharmacokinetic variability. However, weight-based dosing remains the norm globally. The potential clinical impact and cost-effectiveness of pharmacogenomic-guided therapy (PGT) are unknown.

Methods

We constructed a decision tree model to project lifetime costs and benefits of isoniazid PGT for drug-susceptible tuberculosis in Brazil, South Africa, and India. PGT was modeled to reduce isoniazid toxicity among slow NAT2 acetylators and reduce treatment failure among rapid acetylators. The genotyping test was assumed to cost the same as the GeneXpert test. The main outcomes were costs (2018 US dollars), quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios.

Results

In Brazil, PGT gained 19 discounted life-years (23 QALYs) and cost $11 064 per 1000 patients, a value of $476 per QALY gained. In South Africa, PGT gained 15 life-years (19 QALYs) and cost $33 182 per 1000 patients, a value of $1780 per QALY gained. In India, PGT gained 20 life-years (24 QALYs) and cost $13 195 per 1000 patients, a value of $546 per QALY gained. One-way sensitivity analyses showed the cost-effectiveness to be robust to all input parameters. Probabilistic sensitivity analyses were below per capita gross domestic product in all 3 countries in 99% of simulations.

Conclusions

Isoniazid PGT improves health outcomes and would be cost-effective in the treatment of drug-susceptible tuberculosis in Brazil, South Africa, and India.

Estimating the cost of congenital Zika syndrome to families and healthcare providers in Rio de Janeiro and Pernambuco, Brazil: results of a case-control study

Background: Children with congenital Zika syndrome (CZS) have a wide range of additional healthcare needs. This study aimed to estimate the direct costs of CZS from the health provider and family perspectives, and the indirect costs for families, in two Brazilian states: Rio de Janeiro and Pernambuco. Methods: A case-control study was undertaken between May 2017-January 2018 recruiting 174 cases with severe CZS, 41 with mild/moderate CZS and 269 children with no CZS, across the two sites, from existing studies. The primary caregiver was interviewed using a structured questionnaire to collect information on healthcare use and costs incurred during the previous 12 months. In Rio de Janeiro, health care utilization data was also extracted from electronic medical records. We estimated direct and indirect costs incurred as a result of CZS from the perspective of the health system and families. Results: Children with CZS accessed more healthcare facilities and reported longer travel and waiting times than children unaffected by CZS. Total costs from the health provider perspective of outpatient visits, were highest for children with severe CZS (U$1,411) followed by children with mild/moderate CZS (U$264) and children without CZS (U$107). This pattern was apparent for direct costs incurred by families, while median indirect costs were low. Families of children with CZS reported high levels of catastrophic expenditures; Expenses incurred by families to meet their child’s needs as a proportion of household income was 30% (IQR=14%-67%, p<0.01) for children with severe CZS, 11% (IQR=4%-33%, p<0.01) for mild/moderate CZS, and 1% (IQR=0%-8%) for controls. Costs incurred by families were generally higher in Rio de Janeiro than Pernambuco. Conclusions: Families of children affected by CZS in Brazil may need additional public health resources and social benefits to protect them from incurring catastrophic expenses while meeting the needs of their children.

Determining the value of TB active case-finding: current evidence and methodological considerations

Active case-finding (ACF) is an important component of the End TB Strategy. However, ACF is resource-intensive, and the economics of ACF are not well-understood. Data on the costs of ACF are limited, with little consistency in the units and methods used to estimate and report costs. Mathematical models to forecast the long-term effects of ACF require empirical measurements of the yield, timing and costs of case detection. Pragmatic trials offer an opportunity to assess the cost-effectiveness of ACF interventions within a 'real-world´ context. However, such analyses generally require early introduction of economic evaluations to enable prospective data collection on resource requirements. Closing the global case-detection gap will require substantial additional resources, including continued investment in innovative technologies. Research is essential to the optimal implementation, cost-effectiveness, and affordability of ACF in high-burden settings. To assess the value of ACF, we must prioritize the collection of high-quality data regarding costs and effectiveness, and link those data to analytical models that are adapted to local settings.

Cost-effectiveness of newer technologies for the diagnosis of Mycobacterium tuberculosis infection in Brazilian people living with HIV

Tuberculosis is the leading cause of death among people living with HIV (PLH). Preventive tuberculosis therapy reduces mortality in PLH, especially in those with a positive tuberculin skin test (TST). New, more specific technologies for detecting latent tuberculosis infection (LTBI) are now commercially available. We sought to analyse the cost-effectiveness of four different strategies for the diagnosis of LTBI in PLH in Brazil, from the Brazilian public health care system perspective. We developed a Markov state-transition model comparing four strategies for the diagnosis of LTBI over 20 years. The strategies consisted of TST with the currently used protein purified derivative (PPD RT 23), two novel skin tests using recombinant allergens (Diaskintest [Generium Pharmaceutical, Moscow, Russia] and EC [Zhifei Longcom Biologic Pharmacy Co., Anhui, China]), and the QuantiFERON-TB-Gold-Plus (Qiagen, Hilden, Germany). The main outcome was cost (in 2020 US dollars) per quality-adjusted life years (QALY). For the base case scenario, the Diaskintest was dominant over all other examined strategies. The cost saving estimate per QALY was US $1375. In sensitivity analyses, the Diaskintest and other newer tests remained cost-saving compared to TST. For PLH, TST could be replaced by more specific tests in Brazil, considering the current national recommendations.

Cost-Effectiveness of Annual Screening for Tuberculosis among Italian Healthcare Workers: A Retrospective Study

Background. In the past few years, healthcare workers (HCWs) have been considered at higher risk for tuberculosis (TB) infection than the general population. On the other hand, recent studies have reported a low conversion rate among these workers. Recently, the Center for Disease Control (CDC) updated its recommendations, suggesting that an annual screening should not be performed in the absence of a documented exposure but only in workers with high-risk duties or with job tasks in settings at high risk of tuberculosis contagion (e.g., departments of infectious or pulmonary diseases). In fact, some studies showed that annual tuberculosis screening for all the HCWs was not cost-effective in countries with a low incidence of TB. In this study, we evaluated the conversion rate and the cost-effectiveness of two different tuberculosis screening strategies in a large population of Italian HCWs. Methods. In our retrospective study, we reviewed data coming from a tuberculosis screening conducted on 1451 HCWs in a teaching hospital of Rome. All workers were evaluated annually by means of the Quantiferon test (QFT) for a five-year period. Then, the conversion rate was calculated. Results. We found a cumulative conversion rate of 0.6%. Considering the cost of the QFT test (48.26 euros per person), the screening of the HCWs resulted in a high financial burden (38,902.90 euros per seroconversion). Only one seroconversion would have been missed by applying the CDC updated recommendations, with a relevant drop of the costs: 6756.40 euros per seroconversion, with a global save of 296,075.10 euros. Conclusion: The risk of TB conversion among our study population was extremely low and it was related to the risk classification of the setting. Giving these results, the annual tuberculosis screening appeared to not be cost effective. We conclude that a targeted screening would be a better alternative in HCWs with a higher risk of TB exposure.

Tuberculosis among patients treated with TNF inhibitors for rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis in Slovenia: a cohort study

OBJECTIVES

This study aimed to assess the risk of tuberculosis (TB) in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) treated with any of the commercially available tumour necrosis factor inhibitors (TNFis) in Slovenia.

DESIGN

This is a cohort, registry (biorx.si) cross-linked with the Slovenian National TB Registry.

SETTING

National, involving all Slovenian rheumatology centres (six secondary and two secondary/tertiary).

PARTICIPANTS

2429 patients with RA, AS or PsA exposed to at least one TNFi participated in the study.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measures were age-adjusted and sex-adjusted TB incidence rates (IRs) and the standardised incidence ratios (SIRs) compared with the general population exploring different TNFi exposure windows. The secondary outcome measures were a detailed characterisation of the national latent tuberculosis infection (LTBI) screening and TB chemoprophylaxis protocol implementation.

RESULTS

Among the 2429 patients exposed to at least one TNFi for a total of 10 445 (49% RA, 33% AS and 18% PsA) person-years (PY), 99% completed LTBI screening and 6% required TB chemoprophylaxis. Six RA (three adalimumab, three certolizumab), two PsA (two golimumab) and zero AS patients developed TB. Five out of eight had miliary TB, three out of eight had pulmonary TB and two patients died. The age-standardised and sex-standardised TB IR (95% CI) per 100 000 PYs/SIRs (95% CI) compared with the general Slovenian population for the current TNFi exposure were 52 (0 to 110)/6.7 (0.6 to 80), 47 (0 to 110)/6.1 (0.3 to 105), 45 (0 to 109)/5.8 (0.3 to 112) overall, in RA and PsA, respectively.

CONCLUSIONS

The TB IR in the Slovenian patients with RA, AS and PsA treated with TNFi was comparable with TB IRs in TB non-endemic countries with less than a tenth of the patients requiring TB chemoprophylaxis.

Cost-effectiveness of QuantiFERON-TB Gold In-Tube versus tuberculin skin test for diagnosis and treatment of Latent Tuberculosis Infection in primary health care workers in Brazil

Objectives

The goal of this study was to perform a cost-effectiveness analysis from the public health system perspective, comparing five strategies for Latent Tuberculosis Infection (LTBI) diagnosis in primary health care workers in Brazil.

Design

Analytical model for decision making, characterized by cost-effectiveness analysis.

Setting

Primary Care Level, considering primary health care workers in Brazil.

Participants

An analytical model for decision making, characterized by a tree of probabilities of events, was developed considering a hypothetical cohort of 10,000 primary health care workers, using the software TreeAge Pro^™ 2013 to simulate the clinical and economic impacts of new diagnostic technology (QuantiFERON^®-TB Gold in-Tube) versus the traditional tuberculin skin test.

Methods

This model simulated five diagnostic strategies for LTBI in primary health care workers (HCW) in Brazil: tuberculin skin testing using ≥5 mm cut-off, tuberculin skin testing ≥10 mm cut-off, QuantiFERON^®-TB Gold in-Tube, tuberculin skin testing using ≥5 mm cut-off confirmed by QuantiFERON^®-TB Gold In-Tube if TST positive, tuberculin skin testing using ≥10 mm cut-off confirmed by QuantiFERON^®-TB Gold In-Tube if TST positive.

Primary and secondary outcome measures

The outcome measures are the number of individuals correctly classified by the test and the number of Tuberculosis cases avoided.

Results

The most cost-effective strategy was the tuberculin skin test considering ≥10mm cut-off. The isolated use of the QuantiFERON^®-TB Gold In-Tube revealed the strategy of lower efficiency with incremental cost-effectiveness ratio (ICER) of US$ 146.05 for each HCW correctly classified by the test.

Conclusions

The tuberculin skin test using ≥10 mm cut-off was the most cost-effective strategy in the diagnosis of Latent Tuberculosis Infection in primary health care works in Brazil.

Social and economic impacts of congenital Zika syndrome in Brazil: Study protocol and rationale for a mixed-methods study

Global concern broke out in late 2015 as thousands of children in Brazil were born with microcephaly, which was quickly linked to congenital infection with Zika virus (ZIKV). ZIKV is now known to cause a wider spectrum of severe adverse outcomes-congenital Zika syndrome (CZS)-and also milder impairments. This study aimed to explore the social and economic impacts of CZS in Brazil. Data was collected through mixed methods across two settings: Recife City and Jaboatão dos Guararapes in Pernambuco State (the epicentre of the epidemic), and the city of Rio de Janeiro (where reports of ZIKV infection and CZS were less frequent). Data was collected May 2017-January 2018. Ethical standards were adhered to throughout the research. In-depth qualitative interviews were conducted with: mothers and other carers of children with CZS (approximately 30 per setting), pregnant women (10-12 per setting), men and women of child-bearing age (16-20 per setting), and health professionals (10-12 per setting). Thematic analysis was undertaken independently by researchers from at least two research settings, and these were shared for feedback. A case-control study was undertaken to quantitatively explore social and economic differences between caregivers of a child with CZS (cases) and caregivers with an unaffected child (controls). We aimed to recruit 100 cases and 100 controls per setting, from existing studies. The primary caregiver, usually the mother, was interviewed using a structured questionnaire to collect information on: depression, anxiety, stress, social support, family quality of life, health care and social service use, and costs incurred by families. Multivariable logistic regression analyses were used to compare outcomes for cases and controls. Costs incurred as a result of CZS were estimated from the perspective of the health system, families and society. Modelling was undertaken to estimate the total economic burden of CZS from those three perspectives.

Social and economic impacts of congenital Zika syndrome in Brazil: Study protocol and rationale for a mixed-methods study

Global concern broke out in late 2015 as thousands of children in Brazil were born with microcephaly, which was quickly linked to congenital infection with Zika virus (ZIKV). ZIKV is now known to cause a wider spectrum of severe adverse outcomes-congenital Zika syndrome (CZS)-and also milder impairments. This study aimed to explore the social and economic impacts of CZS in Brazil. Data was collected through mixed methods across two settings: Recife City and Jaboatão dos Guararapes in Pernambuco State (the epicentre of the epidemic), and the city of Rio de Janeiro (where reports of ZIKV infection and CZS were less frequent). Data was collected May 2017-January 2018. Ethical standards were adhered to throughout the research. In-depth qualitative interviews were conducted with: mothers and other carers of children with CZS (approximately 30 per setting), pregnant women (10-12 per setting), men and women of child-bearing age (16-20 per setting), and health professionals (10-12 per setting). Thematic analysis was undertaken independently by researchers from at least two research settings, and these were shared for feedback. A case-control study was undertaken to quantitatively explore social and economic differences between caregivers of a child with CZS (cases) and caregivers with an unaffected child (controls). We aimed to recruit 100 cases and 100 controls per setting, from existing studies. The primary caregiver, usually the mother, was interviewed using a structured questionnaire to collect information on: depression, anxiety, stress, social support, family quality of life, health care and social service use, and costs incurred by families. Multivariable logistic regression analyses were used to compare outcomes for cases and controls. Costs incurred as a result of CZS were estimated from the perspective of the health system, families and society. Modelling was undertaken to estimate the total economic burden of CZS from those three perspectives.

Superiority of Interferon Gamma Assay Over Tuberculin Skin Test for Latent Tuberculosis in Inflammatory Bowel Disease Patients in Brazil

BACKGROUND AND AIMS

To compare tuberculin skin test (TST) and interferon gamma release assay (IGRA) in the screening of LTBI among patients with inflammatory bowel disease (IBD) in an endemic area for tuberculosis, to evaluate the need for repeating tests during anti-TNFα, therapy, and to check whether the results may be affected by immunosuppression.

METHODS

A cross-sectional study of 110 IBD patients and 64 controls was conducted in Rio de Janeiro, Brazil. The TST was administered after the Quantiferon(^®)-TB Gold In-tube test was performed.

RESULTS

TST and IGRA agreement was poor regarding diagnosis (kappa: control = 0.318; UC = 0.202; and CD = - 0.093), anti-TNFα therapy (kappa: with anti-TNFα = 0.150; w/o anti-TNFα = - 0.123), and immunosuppressive therapy (IST) (kappa: with IS = - 0.088; w/o IS = 0.146). Indeterminate IGRA was reported in four CD patients on IST. Follow-up tests after anti-TNFα identified conversion in 8.62% using TST and 20.0% using IGRA. Considering IGRA as a criterion standard, TST showed low sensitivity (19.05%) and positive predictive value (PPV) (21.05%). LTBI detection remarkably improved when IGRA was added to TST (sensitivity of 80.95% and PPV of 53.13%). Results were particularly relevant among CD patients where rates started from zero to reach sensitivity and PPV of more than 60%.

CONCLUSION

IGRA alone was more effective to detect LTBI than TST alone and had an overall remarkable added value as an add-on sequential test, particularly in CD patients. While cost-effectiveness of these strategies remains to be evaluated, IGRA appears to be justified in CD prior to and during anti-TNFα therapy, where tuberculosis is endemic.

Do higher cut-off values for tuberculin skin test increase the specificity and diagnostic agreement with interferon gamma release assays in immunocompromised Bacillus Calmette-Guérin vaccinated patients?

PURPOSE

Immunocompromised patients with latent tuberculosis infection (LTBI) are at high risk of progression to active tuberculosis. Detection and treatment of LTBI in this group of patients are very important to control active tuberculosis. Tuberculin skin test (TST) and interferon gamma release assays (IGRAs) are two methods for detection of LTBI. Diagnostic agreement between two tests are poor especially in Bacillus Calmette-Guérin (BCG) vaccinated immunocompromised patients. In this study, we tried to figure out if the use of a higher cut-off for TST increases diagnostic agreement with IGRAs and TST specificity and or not.

MATERIALS/METHODS

In this retrospective study, BCG vaccinated solid organ transplantation (SOT) candidates and patients scheduled for anti-tumor necrosis factor-alpha (anti- TNFα) treatment patients who underwent both TST and IGRAs between 2011 and 2017 were enrolled in the study. Diagnostic agreement between the two tests was assessed for 5, 10, 15mm cut-off values for all participants, SOT candidates and anti- TNFα treatment subgroups separately.

RESULTS

Fifty female and 55 male total 105 patients were included. In the anti- TNFα treatment group 92.8% of the patients were receiving at least one immunosuppressive drug. For all participants kappa (κ) values were 0.303, 0.370, 0.321 respectively for 5, 10 and 15mm cut-offs. For SOT candidates κ values were 0.488, 0.422, 0.288 respectively. For anti- TNFα treatment group κ values were 0.235, 0.332, 0.275 respectively.

CONCLUSIONS

In BCG vaccinated immunocompromised patients, the agreement between TST and QFT-GIT was poor regardless of cut-off value. And increasing the cut-off does not improve agreement.

Tuberculosis infection among cocaine crack users in Brazil

BACKGROUND

WHO recommends treatment for latent tuberculosis infection (LTBI) in the homeless and people who use drugs (PWUD). The optimal test for LTBI screening is uncertain.

METHODS

A cross-sectional study was conducted among the homeless and drug-rehabilitation clinic clients chronically using crack in Western Brazil. Participants were interviewed and offered HIV testing plus tuberculin skin testing (TST) and QuantiFeron®-Gold-in-Tube (QFT). We considered LTBI when either TST or QFT were positive. Factors associated with LTBI were adjusted in a multivariate model.

RESULTS

Among 372 subjects with at least one valid test, 216 (58%) had LTBI. TST was not read in 18.4%; QFT was indeterminate in 2.5%. TST detected 27 (26%) extra LTBI cases among 75 QFT-negative individuals. PWUD had over three-fold odds for LTBI. TST was 4.5 times more likely to be positive in BCG-vaccinated individuals.

CONCLUSION

Given the high risk of progression to disease in this population, the high rates of loss to TST reading and the possibility of false-positive TST results from BCG vaccination, we endorse current CDC recommendations to use QFT for LTBI screening among the homeless and PWUD. However, because adding TST to a negative QFT increased LTBI detection considerably, TST should be considered in QFT-negative individuals.

[Cost-effectiveness in health in Brazil: a systematic review]

A systematic review was performed with the aim of describing the landscape and evolution of cost-effectiveness studies in health in Brazil. The search for articles on cost-effectiveness was performed in the main electronic health databases. The review identified 83 cost-effectiveness studies conducted nationwide. Between the years 1990-2005 there were few studies published on cost-effectiveness, though between 2006 and 2014 there was a significant increase in the number of publications. As for the themes and objectives of the studies, the chronic degenerative diseases and infectious/contagious diseases reflect the epidemiological diversity of Brazil. A predominance of studies on health intervention/treatment was identified. Thus, this review reveals a compatible Brazilian epidemiological reality scenario, indicating a need to increase research and investment of funds in the area of preventive health.

Systematic Review of Health Economic Evaluations of Diagnostic Tests in Brazil: How accurate are the results?

The aim of this study is to identify and characterize the health economic evaluations (HEEs) of diagnostic tests conducted in Brazil, in terms of their adherence to international guidelines for reporting economic studies and specific questions in test accuracy reports. We systematically searched multiple databases, selecting partial and full HEEs of diagnostic tests, published between 1980 and 2013. Two independent reviewers screened articles for relevance and extracted the data. We performed a qualitative narrative synthesis. Forty-three articles were reviewed. The most frequently studied diagnostic tests were laboratory tests (37.2%) and imaging tests (32.6%). Most were non-invasive tests (51.2%) and were performed in the adult population (48.8%). The intended purposes of the technologies evaluated were mostly diagnostic (69.8%), but diagnosis and treatment and screening, diagnosis, and treatment accounted for 25.6% and 4.7%, respectively. Of the reviewed studies, 12.5% described the methods used to estimate the quantities of resources, 33.3% reported the discount rate applied, and 29.2% listed the type of sensitivity analysis performed. Among the 12 cost-effectiveness analyses, only two studies (17%) referred to the application of formal methods to check the quality of the accuracy studies that provided support for the economic model. The existing Brazilian literature on the HEEs of diagnostic tests exhibited reasonably good performance. However, the following points still require improvement: 1) the methods used to estimate resource quantities and unit costs, 2) the discount rate, 3) descriptions of sensitivity analysis methods, 4) reporting of conflicts of interest, 5) evaluations of the quality of the accuracy studies considered in the cost-effectiveness models, and 6) the incorporation of accuracy measures into sensitivity analyses.

Evaluation of a New IFN-γ Release Assay for Rapid Diagnosis of Active Tuberculosis in a High-Incidence Setting

Blood-based interferon-gamma (IFN-γ) release assays (IGRAs) have been proven to be useful in the diagnosis of Mycobacterium tuberculosis (Mtb) infection. However, IGRAs have not been recommended for clinical practice in most low-income settings due to cost-intensive limitations and shortage of clinical data available. The established T-SPOT. TB assay containing Mtb-specific antigens ESAT-6 and CFP10 are widely used for immunodiagonsis of Mtb infection, but the high cost is one of the restricting factors against its clinical application in the developing countries. More recently, a cost-saving IGRA assay, TS-SPOT, was approved in China. This new assay contains an additional antigen Rv3615c. Rv3615c contains broadly recognized CD4⁺ and CD8⁺ epitopes, and T-cell responses to Rv3615c are as specific for Mtb infection as the responses to ESAT-6 and CFP10 in both Mtb-infected humans and M. bovis-infected cattle. Therefore, we assessed the likely effect of inclusion of Rv3615c as stimulus besides ESAT-6 and CFP10 in an IGRA assay and evaluated the performance of TS-SPOT for diagnosis of Mtb infection and active TB compared with T-SPOT.TB. We tested 155 active TB patients, 90 non-TB lung disease patients, and 55 healthy individuals. The results presented an improved positive rate for diagnosis of active TB and Mtb infection, that could be attributable to inclusion of Rv3615c in the mixture of stimulatory antigens. The diagnostic efficiency of TS-SPOT assay for active TB was as follows: sensitivity 80.00%, specificity 83.45%, positive predictive value (PPV) 83.78%, negative predictive value (NPV) 83.45%, positive likelihood ratio (LR+) 4.83, and negative likelihood ratio (LR−) 0.24. The results were similar to those of T-SPOT.TB, with an excellent agreement (κ = 0.91, 95% CI: 0.85–0.95) being observed between these two assays. The sensitivities of the TS-SPOT assay varied for patients with different forms of active TB, with the highest sensitivity for patients with culture-positive pulmonary TB (92.16%) and the lowest for those with tuberculosis meningitis (50.00%). Taken together, the current evidence indicates that this new TS-SPOT assay is a useful adjunct to the current tests for rapid diagnosis of active TB and Mtb infection in low-income and high-incidence settings due to its characteristics of cost-effectiveness and high-quality.

Close contact interferon-gamma response to the new PstS1(285-374):CPF10: a preliminary 1-year follow-up study

Background

The available diagnostic tools for latent tuberculosis (TB) infection (LTBI) via interferon-gamma (IFN-g) release assays (IGRA) are based on ESAT6:CFP10 stimulation. However, the mycobacterial antigen PstS1 is also highly immunogenic and some of its fragments, such as PstS1_(285–374), have shown higher immunoreactivity in LTBI than in active TB. PstS1_(285–374), therefore, could increase the accuracy of the existing IGRA to detect LTBI. Thus, a new chimeric protein has recently been developed (PstS1_(285–374):CFP10) showing potential for LTBI screening of recent close contacts (rCt) exposed to Mycobacterium tuberculosis. The aim of this study was to analyze the PstS1_(285–374):CFP10 longitudinal IFN-g profile in comparison to ESAT6:CFP10 and full PstS1/CFP10 stimulation in a rCt cohort and correlate the responses to these in-house IGRA with any clinical changes/interventions that might occur.

Methods

A free-of-cost, one-year follow up was offered to 120 rCt recruited in Rio de Janeiro, RJ, Brazil. Whole blood short-term (WBA), long-term stimulation (LSA) assays, and the tuberculin skin test (TST) were performed during follow up.

Results

Among the enrolled rCt, 44.2% (53/120) returned for re-evaluation and the control group (TST negative, n = 17) showed low IFN-g reactivity to all antigen stimulations during the entire follow up, except for one participant who had shown radiological evidence of past TB/LTBI. Both incident cases were detected by IGRA-PstS1_(285–374):CFP10 during LTBI and after disease progression. Moreover, subsequent to the prophylactic treatment for LTBI (tLTBI), a significant regression in the LSA response was predominantly observed through stimulation of the new chimeric protein (8/10, 80%) followed by ESAT6:CFP10 (5/10, 50%) and PstS1/CFP10 (4/10, 40%). No clinical or epidemiological characteristics were exclusively shared among IGRA convertors.

Conclusion

It was demonstrated that the TST negative rCt without radiological evidence of LTBI/TB did not develop an IGRA-PstS1_(285–374):CFP10 response during the one-year follow up. Moreover, all incident cases were detected by our new IGRA; and a significant decrement of LSA-PstS1_(285–374):CFP10 reactivity post-prophylactic tLTBI was found. To our knowledge, this is the first study to monitor changes in the immune response profile of IGRA-PstS1_(285–374):CFP10 among rCt during a consecutive one-year period, thus providing additional evidence of its potential in the detection of LTBI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-016-2360-4) contains supplementary material, which is available to authorized users.

Mycobacterium Tuberculosis Infection, Immigration Status, and Diagnostic Discordance: A Comparison of Tuberculin Skin Test and QuantiFERON-TB Gold In-Tube Test Among Immigrants to the U.S

OBJECTIVE

We used a recent source of nationally representative population data on tuberculosis (TB) infection to characterize concordance between the tuberculin skin test (TST) and the QuantiFERON-TB Gold In-Tube (QFT-GIT) blood test for immigrants in the United States.

METHODS

We used TB screening data from the 2011-2012 National Health and Nutrition Examination Survey to examine concordance between the TST and QFT-GIT--an interferon-gamma release assay (IGRA) blood test--for 7,097 U.S. natives, naturalized citizens, and noncitizens.

RESULTS

Consistent with prior findings, one in five immigrants in the survey was identified with latent TB infection (LTBI), a rate 14 times higher than for U.S. natives. We also found higher rates of discordant TST/IGRA results among immigrants than among U.S. natives. Unadjusted discordance between TST and IGRA was 3% among U.S. natives (weighted N=5,684,274 of 191,179,213) but ranged up to 19% for noncitizens (weighted N=3,722,960 of 19,377,147). Adjusting for age, sex, and race/ethnicity, noncitizens had more than nine times the odds of having a positive TST result but negative QFT-GIT result compared with U.S. natives.

CONCLUSIONS

Our findings suggest that whether and how either of these tests should be deployed is highly context sensitive. Significant discordance in test results when used among immigrants raises the possibility of missed opportunities for harm reduction in this already at-risk population. However, we found little distinction between the tests in terms of diagnostic outcome when used in a U.S. native population, suggesting little benefit to the adoption and use of the QFT-GIT test in place of TST on the basis of test performance alone for this population.

The cost-effectiveness of treating triple coinfection with HIV, tuberculosis and hepatitis C virus

OBJECTIVES

The objective of this study was to estimate the cost-effectiveness of treating patients infected with HIV and simultaneously coinfected with tuberculosis (TB) and hepatitis C virus (HCV).

METHODS

A mathematical model for HIV coinfection with TB and HCV is introduced. The model was designed to incorporate parameters of control for the coverage of care, which makes it useful for performing cost-effectiveness analysis of public policies. A cost-effectiveness analysis of early medical care of patients with TB and HCV coinfection, with coverage of 0 (basal), 25, 50, 75 and 100%, was performed for the whole cohort of patients and a special analysis was performed in a selected population with triple infection.

RESULTS

The cost per resolved infection and the cost per year of life gained were found to be very cost-effective for the population with triple infection, for all different coverages.

CONCLUSIONS

It is known that treating patients with HIV who are coinfected with TB or HCV implies high cost and low efficacy, but it is possible that the population with triple infections could achieve important benefits in terms of years of life gained.

Methods Used in Economic Evaluations of Tuberculin Skin Tests and Interferon Gamma Release Assays for the Screening of Latent Tuberculosis Infection: A Systematic Review

BACKGROUND

Latent tuberculosis infection (LTBI) provides a constant pool of new active tuberculosis cases; a third of the earth's population is estimated to be infected with LTBI.

OBJECTIVE

The objective of this systematic review was to assess the quality and summarize the available evidence from published economic evaluations reporting on the cost-effectiveness of tuberculin skin tests (TSTs) compared with interferon gamma release assays (IGRAs) for the screening of LTBI.

METHODS

An extensive systematic review of the published literature was conducted. A two-step process was adopted to identify relevant articles: information was extracted into evidence tables and then analyzed. The quality of the publications was assessed using a 10-item checklist specific for economic evaluations.

RESULTS

Twenty-eight studies were identified for inclusion in this review. Most of the studies found IGRAs to be more cost-effective than TSTs; however, the conclusions from the studies varied significantly. Most studies scored highly on the checklist although only one fulfilled all the stipulated criteria. A wide variety of methodological approaches were documented; identified differences included the type of economic evaluation and model, time horizon, perspective, and outcomes measures.

CONCLUSIONS

The lack of consistent methods across studies makes it difficult to draw any firm conclusions about the most cost-effective option between TSTs and IGRAs. This problem can be solved by improving the quality of economic evaluation studies in the field of LTBI screening, through adherence to quality checklists.

Profile of interferon-gamma response to latency-associated and novel in vivo expressed antigens in a cohort of subjects recently exposed to Mycobacterium tuberculosis

Recently some latency-associated antigens (LAA) of Mycobacterium tuberculosis were described, as Rv2029c, Rv2031c, Rv2034, Rv2628 and Rv3353c. Of which, the Rv2034 and Rv3353c also demonstrated in vivo expression. Therefore evaluating the immune response to these antigens may help to understand their role in latent TB infection. In a 1-year longitudinal study, IFN-γ response by in vitro peripheral blood mononuclear cells stimulation with LAA was investigated in subjects recently exposed to TB, classified by IFN-γ release assay (IGRA) using RD1 antigens (ESAT-6:CFP-10) and tuberculin skin test (TST) response. Except for Rv3353c, all the LAA triggered higher mean IFN-γ response in IGRA-RD1(+) groups (p < 0.05). Combining the IFN-γ-responders to Rv2029c, Rv2031c plus Rv2034 detected 90.3% (28/31) of IGRA-RD1(+) and 66.7% (24/36) of TST(+) contacts, while 95% (19/20) and 11% (2/17) were identified by classifying them according to a TST and IGRA-RD1 double-positive or double-negative response, respectively. In the follow-up, the TST convertors (negative to positive) also demonstrated an IFN-γ conversion to Rv2029c and Rv2031c, whereas the unique TB incident case was exclusively detected via IGRA-Rv2029c and TST before developing TB. A reversion rate to LAA (60%-100%) after prophylactic treatment was observed at TST(+)/IGRA-RD1(+) group. Further studies into the performance of these antigens are thus warranted.

Evaluation of a domestic interferon-gamma release assay for detecting Mycobacterium tuberculosis infection in China

Interferon-gamma release assays (IGRAs) have been demonstrated to be useful in the diagnosis of Mycobacterium tuberculosis (MTB) infection. However, IGRAs have not been recommended for clinical usage in most low-income countries due to the shortage of clinical data available resulting from their high test cost. Recently, a cheaper domestic TB-IGRA was approved in China. In this study, we compared TB-IGRA with QuantiFERON-TB Gold In-Tube (QFT-GIT) for MTB infection diagnosis in 253 active TB patients, 48 non-TB lung disease patients, 115 healthcare workers and 216 healthy individuals. The proportion of positive TB-IGRA results in active TB patients, patients with non-TB lung disease, healthcare workers and healthy individuals was 88.3%, 27.1%, 40.9% and 17.6%, respectively, which was similar to the results of QFT-GIT, with an overall agreement of 95% (κ = 0.89) and a high correlation between their responses (r = 0.85, p < 0.001) being observed. In conclusion, the TB-IGRA has comparable clinical performance with QFT-GIT.

Smear plus Detect-TB for a sensitive diagnosis of pulmonary tuberculosis: a cost-effectiveness analysis in an incarcerated population

Background

Prison conditions can favor the spread of tuberculosis (TB). This study aimed to evaluate in a Brazilian prison: the performance and accuracy of smear, culture and Detect-TB; performance of smear plus culture and smear plus Detect-TB, according to different TB prevalence rates; and the cost-effectiveness of these procedures for pulmonary tuberculosis (PTB) diagnosis.

Methods

This paper describes a cost-effectiveness study. A decision analytic model was developed to estimate the costs and cost-effectiveness of five routine diagnostic procedures for diagnosis of PTB using sputum specimens: a) Smear alone, b) Culture alone, c) Detect-TB alone, d) Smear plus culture and e) Smear plus Detect-TB. The cost-effectiveness ratio of costs were evaluated per correctly diagnosed TB case and all procedures costs were attributed based on the procedure costs adopted by the Brazilian Public Health System.

Results

A total of 294 spontaneous sputum specimens from patients suspected of having TB were analyzed. The sensibility and specificity were calculated to be 47% and 100% for smear; 93% and 100%, for culture; 74% and 95%, for Detect-TB; 96% and 100%, for smear plus culture; and 86% and 95%, for smear plus Detect-TB. The negative and positive predictive values for smear plus Detect-TB, according to different TB prevalence rates, ranged from 83 to 99% and 48 to 96%, respectively. In a cost-effectiveness analysis, smear was both less costly and less effective than the other strategies. Culture and smear plus culture were more effective but more costly than the other strategies. Smear plus Detect-TB was the most cost-effective method.

Conclusions

The Detect-TB evinced to be sensitive and effective for the PTB diagnosis when applied with smear microscopy. Diagnostic methods should be improved to increase TB case detection. To support rational decisions about the implementation of such techniques, cost-effectiveness studies are essential, including in prisons, which are known for health care assessment problems.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0678-x) contains supplementary material, which is available to authorized users.

Diagnosis of latent tuberculosis infection before initiation of anti-tumor necrosis factor therapy using both tuberculin skin test and QuantiFERON-TB Gold In Tube assay

BACKGROUND

Reactivation of latent tuberculosis infection (LTBI) is an important complication in patients treated with tumor necrosis factor-alpha (TNF-α) blocking agents. However, the best method for LTBI detection before initiation of anti-TNF therapy remains to be determined.

METHODS

From January 2010 to August 2013, anti-TNF therapy was initiated in 426 patients with immune-mediated inflammatory diseases (IMIDs). Tuberculin skin test (TST) and Quantiferon-TB Gold In Tube (QFT-GIT) assay were performed before starting anti-TNF treatment. LTBI was defined as a positive TST (induration ≥ 10 mm) or as a positive QFT-GIT result. Patients were followed up until December 2013.

RESULTS

The positive TST and QFT-GIT rates were 22.3% (95/426) and 16.0% (68/426), respectively, yielding a total of 27.0% (115/426) of positive LTBI results. LTBI treatment was initiated in 25.1% (107/426) and was completed in 100% (107/107) of patients. During a median 294 days of follow-up, active TB occurred in 1.4% (6/426) of the patients with negative TST and QFT-GIT results at baseline.

CONCLUSION

The either test positive strategy, using both TST and QFT-GIT assay, is acceptable for LTBI screening before commencing anti-TNF therapy in patients with IMIDs.

Added value of QuantiFERON TB-gold in-tube for detecting latent tuberculosis infection among persons living with HIV/AIDS

OBJECTIVE

To evaluate the added value of QuantiFERON TB-Gold in-Tube (QTF-GIT) over the tuberculin skin testing (TST) for detecting latent tuberculosis (TB) infection (LTBI) among patients with AIDS in a city with a low TB incidence rate (11.1/100,000 inhabitants) and universal BCG coverage.

METHODS

Three hundred consecutive patients with AIDS in eight outpatient sexually transmitted disease public clinics in Brasilia were submitted to QFT-IT and TST between May 2011 and March 2013. A positive result of either test was considered to be LTBI.

RESULTS

Median CD4-cell count was 477.5 cells/mm(3); 295 (98.3%) were using antiretroviral therapy. Eighteen patients (6%, 95% CI: 3.6%-9.3%) had LTBI, of whom 4 (1.3%, 95% CI: 0.04%-2.63%) had only a positive TST, 8 (2.7%, 95% CI: 0.8%-4.5%) had only a QFT-GIT positive test, and 6 (2%, 95% CI: 0.4%-3.6%) had positive results for both tests. This represents an 81.8% relative increase in LTBI detection when QFT-GIT is added to TST. The concordance between both tests was 96% (k = 0.48).

CONCLUSIONS

The QFT-GIT alone was more effective to detect LTBI than TST alone and had an 81% added value as an add-on sequential test in this population with mild immunosuppression. The cost-effectiveness of these strategies remains to be evaluated.

Performance of QuantiFERON-TB Gold In-Tube test and Tuberculin Skin Test for diagnosis of latent tuberculosis infection in BCG vaccinated health care workers

Background

Tuberculin skin test (TST) has been used for years as an aid in diagnosing latent tuberculosis infection (LTBI) but it suffers from a number of well-documented performance and logistic problems. Quantiferon-TB Gold In Tube test (QFT-GIT) has been reported to have better sensitivity and specifity than TST. In this study, it was aimed to compare the performance of a commercial IFN-γ release assay (QFT-GIT) with TST in the diagnosis of HCWs at risk for latent TB infection in BCG vaccinated population.

Material/Methods

Hundred healthy volunteer health care workers were enrolled. All were subjected to TST and QFT-GIT. Results were compared among Health Care Workers (HCWs) groups in terms of profession, workplace, working duration.

Results

TST is affected by previous BCG vaccinations and number of cases with QFT-GIT positivity is increased in accordance with the TST induration diameter range. QFT-GIT result was negative in 17 of 32 TST positive (≥15 mm) cases and positive in 4 of 61 cases whose TST diameters are between 6–14 mm, that is attritutable to previous BCG vaccination(s). It was negative in all cases with TST diameters between 0–5 mm.

HCWs with positive QFT-GIT results were significantly older than the ones with negative results. Furthermore duration of work was significantly longer in QFT-GIT positive than in negative HCWs.

Conclusions

There was a moderate concordance between QFT-GIT and TST, when TST result was defined as positive with a ≥15 mm diameter of induration. We suggest that QFT-GIT can be used as an alternative to TST for detection of LTBI, especially in groups with high risk of LTBI and in population with routine BCG vaccination program.