Cost-effectiveness of using Quantiferon Gold (QFT-G)® versus tuberculin skin test (TST) among U.S. and foreign born populations at a public health department clinic with a low prevalence of tuberculosis

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.

Primary care providers' and nurses' knowledge, attitudes, and skills regarding latent TB infection testing and treatment: A qualitative study from Rhode Island

Background

Untreated latent tuberculosis infection (LTBI) is a major source of active tuberculosis disease in the United States. In 2016, the United States Preventive Services Task Force (USPSTF) recommended that screening for latent tuberculosis infection among individuals at increased risk be performed as routine preventive care. Traditionally, LTBI management–including both testing and treatment–has been conducted by specialists in the United States. It is believed that knowledge gaps among primary care team members and discomfort with LTBI treatment are significant barriers to LTBI management being conducted in primary care.

Methods and objectives

This qualitative study sought to evaluate the knowledge, attitudes, and skills of primary care team members regarding the LTBI care cascade, and to identify each stepwise barrier limiting primary care teams in following the USPSTF recommendations.

Results

We conducted 24 key informant interviews with primary care providers and nurses in Rhode Island. Our results demonstrate that overall, few primary care providers and nurses felt comfortable with LTBI management, and their confidence and comfort decreased throughout the cascade. Participants felt least confident with LTBI treatment and held misconceptions about LTBI testing, such as high cost. Although participants were not confident about LTBI treatment, most were enthusiastic about treating patients if provided additional training. Participants suggested that their lack of knowledge regarding LTBI treatment led to high rates of referral to specialist providers.

Conclusion

The gaps revealed in this study can inform training curricula for primary care team members in Rhode Island and nationally to shift the USPSTF policy into practice, and, ultimately, contribute to TB elimination in the United States.

Resource implications of the latent tuberculosis cascade of care: a time and motion study in five countries

BACKGROUND

The End TB Strategy calls for global scale-up of preventive treatment for latent tuberculosis infection (LTBI), but little information is available about the associated human resource requirements. Our study aimed to quantify the healthcare worker (HCW) time needed to perform the tasks associated with each step along the LTBI cascade of care for household contacts of TB patients.

METHODS

We conducted a time and motion (TAM) study between January 2018 and March 2019, in which consenting HCWs were observed throughout a typical workday. The precise time spent was recorded in pre-specified categories of work activities for each step along the cascade. A linear mixed model was fit to estimate the time at each step.

RESULTS

A total of 173 HCWs in Benin, Canada, Ghana, Indonesia, and Vietnam participated. The greatest amount of time was spent for the medical evaluation (median: 11 min; IQR: 6-16), while the least time was spent on reading a tuberculin skin test (TST) (median: 4 min; IQR: 2-9). The greatest variability was seen in the time spent for each medical evaluation, while TST placement and reading showed the least variability. The total time required to complete all steps along the LTBI cascade, from identification of household contacts (HHC) through to treatment initiation ranged from 1.8 h per index TB patient in Vietnam to 5.2 h in Ghana.

CONCLUSIONS

Our findings suggest that the time requirements are very modest to perform each step in the latent TB cascade of care, but to achieve full identification and management of all household contacts will require additional human resources in many settings.

The effectiveness and cost-effectiveness of screening for latent tuberculosis among migrants in the EU/EEA: a systematic review

Migrants account for a large and growing proportion of tuberculosis (TB) cases in low-incidence countries in the European Union/European Economic Area (EU/EEA) which are primarily due to reactivation of latent TB infection (LTBI). Addressing LTBI among migrants will be critical to achieve TB elimination. Methods: We conducted a systematic review to determine effectiveness (performance of diagnostic tests, efficacy of treatment, uptake and completion of screening and treatment) and a second systematic review on cost-effectiveness of LTBI screening programmes for migrants living in the EU/EEA. Results: We identified seven systematic reviews and 16 individual studies that addressed our aims. Tuberculin skin tests and interferon gamma release assays had high sensitivity (79%) but when positive, both tests poorly predicted the development of active TB (incidence rate ratio: 2.07 and 2.40, respectively). Different LTBI treatment regimens had low to moderate efficacy but were equivalent in preventing active TB. Rifampicin-based regimens may be preferred because of lower hepatotoxicity (risk ratio = 0.15) and higher completion rates (82% vs 69%) compared with isoniazid. Only 14.3% of migrants eligible for screening completed treatment because of losses along all steps of the LTBI care cascade. Limited economic analyses suggest that the most cost-effective approach may be targeting young migrants from high TB incidence countries. Discussion: The effectiveness of LTBI programmes is limited by the large pool of migrants with LTBI, poorly predictive tests, long treatments and a weak care cascade. Targeted LTBI programmes that ensure high screening uptake and treatment completion will have greatest individual and public health benefit.

Defining a migrant-inclusive tuberculosis research agenda to end TB

BACKGROUND

Pillar 3 of the End TB Strategy calls for the promotion of research and innovation at the country level to facilitate improved implementation of existing and novel interventions to end tuberculosis (TB). In an era of increasing cross-border migration, there is a specific need to integrate migration-related issues into national TB research agendas. The objective of the present review is to provide a conceptual framework to guide countries in the development and operationalization of a migrant-inclusive TB research agenda.

METHODS

We conducted a literature review, complemented by expert opinion and the previous articles in this State of the Art series, to identify important themes central to migration-related TB. We categorized these themes into a framework for a migration-inclusive global TB research agenda across a comprehensive spectrum of research. We developed this conceptual framework taking into account: 1) the biomedical, social and structural determinants of TB; 2) the epidemiologic impact of the migration pathway; and 3) the feasibility of various types of research based on a country's capacity.

DISCUSSION

The conceptual framework presented here is based on the key principle that migrants are not inherently different from other populations in terms of susceptibility to known TB determinants, but that they often have exacerbated or additional risks related to their country of origin and the migration process, which must be accounted for in developing comprehensive TB prevention and care strategies. A migrant-inclusive research agenda should systematically consider this wider context to have the highest impact.

The Prevalence of Latent Tuberculosis Infection in the United States

RATIONALE

Individuals with latent tuberculosis infection (LTBI) represent a reservoir of infection, many of whom will progress to tuberculosis (TB) disease. A central pillar of TB control in the United States is reducing this reservoir through targeted testing and treatment.

OBJECTIVES

To estimate the prevalence of LTBI in the United States using the tuberculin skin test (TST) and an IFN-γ release assay.

METHODS

We used nationally representative data from the 2011-2012 National Health and Nutrition Examination Survey (n = 6,083 aged ≥6 yr). LTBI was measured by both the TST and QuantiFERON-TB Gold In-Tube test (QFT-GIT). Weighted population, prevalence, and multiple logistic regression were used.

MEASUREMENTS AND MAIN RESULTS

The estimated prevalence of LTBI in 2011-2012 was 4.4% as measured by the TST and 4.8% by QFT-GIT, corresponding to 12,398,000 and 13,628,000 individuals, respectively. Prevalence declined slightly since 2000 among the U.S. born but remained constant among the foreign born. Earlier birth cohorts consistently had higher prevalence than more recent ones. Higher risk groups included the foreign born, close contact with a case of TB disease, and certain racial/ethnic groups.

CONCLUSIONS

After years of decline, the prevalence of LTBI remained relatively constant between 2000 and 2011. A large reservoir of 12.4 million still exists, with foreign-born persons representing an increasingly larger proportion of this reservoir (73%). Estimates and risk factors for LTBI were generally similar between the TST and QFT-GIT. The updated estimates of LTBI and associated risk groups can help improve targeted testing and treatment in the United States.

The impact of migration on tuberculosis epidemiology and control in high-income countries: a review

Tuberculosis (TB) causes significant morbidity and mortality in high-income countries with foreign-born individuals bearing a disproportionate burden of the overall TB case burden in these countries. In this review of tuberculosis and migration we discuss the impact of migration on the epidemiology of TB in low burden countries, describe the various screening strategies to address this issue, review the yield and cost-effectiveness of these programs and describe the gaps in knowledge as well as possible future solutions.The reasons for the TB burden in the migrant population are likely to be the reactivation of remotely-acquired latent tuberculosis infection (LTBI) following migration from low/intermediate-income high TB burden settings to high-income, low TB burden countries.TB control in high-income countries has historically focused on the early identification and treatment of active TB with accompanying contact-tracing. In the face of the TB case-load in migrant populations, however, there is ongoing discussion about how best to identify TB in migrant populations. In general, countries have generally focused on two methods: identification of active TB (either at/post-arrival or increasingly pre-arrival in countries of origin) and secondly, conditionally supported by WHO guidance, through identifying LTBI in migrants from high TB burden countries. Although health-economic analyses have shown that TB control in high income settings would benefit from providing targeted LTBI screening and treatment to certain migrants from high TB burden countries, implementation issues and barriers such as sub-optimal treatment completion will need to be addressed to ensure program efficacy.

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.

A scoping review of cost-effectiveness of screening and treatment for latent tubercolosis infection in migrants from high-incidence countries

Background

In low-incidence countries, most tuberculosis (TB) cases occur among migrants and are caused by reactivation of latent tuberculosis infection (LTBI) acquired in the country of origin. Diagnosis and treatment of LTBI are rarely implemented to reduce the burden of TB in immigrants, partly because the cost-effectiveness profile of this intervention is uncertain.

The objective of this research is to perform a review of the literature to assess the cost-effectiveness of LTBI diagnosis and treatment strategies in migrants.

Methods

Scoping review of economic evaluations on LTBI screening strategies for migrants was carried out in Medline.

Results

Nine studies met the inclusion criteria. LTBI screening was cost-effective according to seven studies. Findings of four studies support interferon gamma release assay as the most cost-effective test for LTBI screening in migrants. Two studies found that LTBI screening is cost-effective only if carried out in immigrants who are contacts of active TB cases.

Discussion and Conclusions

Our findings support the cost-effectiveness of LTBI diagnostic and treatment strategies in migrants especially if they are focused on young subjects from high incidence countries. These strategies could represent and adjunctive and synergistic tool to achieve the ambitious aim of TB elimination.

Electronic supplementary material

The online version of this article (doi:10.1186/s12913-015-1045-3) contains supplementary material, which is available to authorized users.

The effectiveness of screening with interferon-gamma release assays in a university health care setting with a diverse global population

OBJECTIVE

This analysis examined the effectiveness of utilizing interferon-gamma release assay (IGRA) technology in a TB (TB) screening program at a university.

PARTICIPANTS

Participants were 2299 students at a Montana university who had presented to the university health center for TB screening during 2012 and 2013.

METHODS

A retrospective study was conducted utilizing data from student health center medical records. Time and financial expenditures were determined, and the cost of the present screening process and 2 alternative scenarios was calculated.

RESULTS

The current process is the most costly and time-consuming scenario for TB testing. Testing exclusively with IGRAs is the least labor-intensive for staff and creates revenue, whereas a dual method, utilizing IGRAs for high-risk students and skin tests for others, provides a solution that better responds to the demographic of the population.

CONCLUSIONS

This assessment shows that IGRAs are a cost-effective tool for screening a global student population.

Estimated Prevalence of Tuberculosis Infection Among a New York City Clinic Population Using Interferon-gamma Release Assays

Using QuantiFERON®-Gold In-Tube (QFT-GIT) data, the prevalence of tuberculosis infection in New York City was estimated. Patient characteristics associated with a positive result were consistent with known tuberculosis risk factors. Results suggest that blood-based tests for tuberculosis infection are reliable.

Background

 Elimination of tuberculosis (TB) in the United States requires treating not only persons with active disease but also those infected with TB. Achieving this goal requires understanding local TB infection prevalence and identifying subgroups at increased risk for infection and disease.

Methods

 The study population included all patients tested with an interferon-gamma release assay (IGRA) test at New York City (NYC) public TB clinics from October 1, 2006 to December 31, 2011. Patients who were not a case or contact at testing (general clinic patients) and who had a positive QuantiFERON-Gold In-Tube (QFT-GIT) test result were compared with those with indeterminate or negative results to identify characteristics associated with positive results. New York City TB surveillance data were used to identify clinic patients later diagnosed with active TB disease.

Results

 A total of 69 273 IGRA tests were conducted. Among 20 066 patients tested with QFT-GIT, 16% tested positive, 83% tested negative, and <1% were indeterminate. Of 18 481 general clinic patients, 14% had a positive QFT-GIT result. Nine percent of United States-born patients compared with 19% of foreign-born patients had a positive result. Increasing age and birth in a high-incidence country were associated with a higher likelihood of having a positive result. One patient with a negative QFT-GIT result was identified as a TB case 2 years later.

Conclusions

 Using QFT-GIT data, the background prevalence of TB infection in NYC was estimated. Patient characteristics associated with a positive QFT-GIT result were consistent with known TB risk factors. Results suggest that IGRAs are reliable tests for TB infection.