Cost-Effectiveness of Quantiferon®-TB Gold-In-Tube Versus Tuberculin Skin Testing for Contact Screening and Treatment of Latent Tuberculosis Infection in Brazil

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Abstract

Background

Latent tuberculosis infection (LTBI) is a reservoir for new TB cases. Isoniazid preventive therapy (IPT) reduces the risk of active TB by as much as 90%, but LTBI screening has limitations. Unlike tuberculin skin testing (TST), interferon-gamma release assays are not affected by BCG vaccination, and have been reported to be cost-effective in low-burden countries. The goal of this study was to perform a cost-effectiveness analysis from the health system perspective, comparing three strategies for LTBI diagnosis in TB contacts: tuberculin skin testing (TST), QuantiFERON®-TB Gold-in-Tube (QFT-GIT) and TST confirmed by QFT-GIT if positive (TST/QFT-GIT) in Brazil, a middle-income, high-burden country with universal BCG coverage.

Methodology/Principal Findings

Costs for LTBI diagnosis and treatment of a hypothetical cohort of 1,000 adult immunocompetent close contacts were considered. The effectiveness measure employed was the number of averted TB cases in two years. Health system costs were US$ 105,096 for TST, US$ 121,054 for QFT-GIT and US$ 101,948 for TST/QFT-GIT; these strategies averted 6.56, 6.63 and 4.59 TB cases, respectively. The most cost-effective strategy was TST (US$ 16,021/averted case). The incremental cost-effectiveness ratio was US$ 227,977/averted TB case for QFT-GIT. TST/QFT-GIT was dominated.

Conclusions

Unlike previous studies, TST was the most cost-effective strategy for averting new TB cases in the short term. QFT-GIT would be more cost-effective if its costs could be reduced to US$ 26.95, considering a TST specificity of 59% and US$ 18 considering a more realistic TST specificity of 80%. Nevertheless, with TST, 207.4 additional people per 1,000 will be prescribed IPT compared with QFT.

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Most cited references 36

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Systematic review: T-cell-based assays for the diagnosis of latent tuberculosis infection: an update.

Madhukar Pai, Alice Zwerling, Dick Menzies (2008)

Interferon-gamma-release assays (IGRAs) are alternatives to the tuberculin skin test (TST). A recent meta-analysis showed that IGRAs have high specificity, even among populations that have received bacille Calmette-Guérin (BCG) vaccination. Sensitivity was suboptimal for TST and IGRAs. To incorporate newly reported evidence from 20 studies into an updated meta-analysis on the sensitivity and specificity of IGRAs. PubMed was searched through 31 March 2008, and citations of all original articles, guidelines, and reviews for studies published in English were reviewed. Studies that evaluated QuantiFERON-TB Gold, QuantiFERON-TB Gold In-Tube (both from Cellestis, Victoria, Australia), and T-SPOT.TB (Oxford Immunotec, Oxford, United Kingdom) or its precommercial ELISpot version, when data on the commercial version were lacking. For assessing sensitivity, the study sample had to have microbiologically confirmed active tuberculosis. For assessing specificity, the sample had to comprise healthy, low-risk individuals without known exposure to tuberculosis. Studies with fewer than 10 participants and those that included only immunocompromised participants were excluded. One reviewer abstracted data on participant characteristics, test characteristics, and test performance from 38 studies; these data were double-checked by a second reviewer. The original investigators were contacted for additional information when necessary. A fixed-effects meta-analysis with correction for overdispersion was done to pool data within prespecified subgroups. The pooled sensitivity was 78% (95% CI, 73% to 82%) for QuantiFERON-TB Gold, 70% (CI, 63% to 78%) for QuantiFERON-TB Gold In-Tube, and 90% (CI, 86% to 93%) for T-SPOT.TB. The pooled specificity for both QuantiFERON tests was 99% among non-BCG-vaccinated participants (CI, 98% to 100%) and 96% (CI, 94% to 98%) among BCG-vaccinated participants. The pooled specificity of T-SPOT.TB (including its precommercial ELISpot version) was 93% (CI, 86% to 100%). Tuberculin skin test results were heterogeneous, but specificity in non-BCG-vaccinated participants was consistently high (97% [CI, 95% to 99%]). Most studies were small and had limitations, including no gold standard for diagnosing latent tuberculosis and variable TST methods and cutoff values. Data on the specificity of the commercial T-SPOT.TB assay were limited. The IGRAs, especially QuantiFERON-TB Gold and QuantiFERON-TB Gold In-Tube, have excellent specificity that is unaffected by BCG vaccination. Tuberculin skin test specificity is high in non-BCG-vaccinated populations but low and variable in BCG-vaccinated populations. Sensitivity of IGRAs and TST is not consistent across tests and populations, but T-SPOT.TB appears to be more sensitive than both QuantiFERON tests and TST.

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6-month versus 36-month isoniazid preventive treatment for tuberculosis in adults with HIV infection in Botswana: a randomised, double-blind, placebo-controlled trial.

Oaitse Motsamai, Lorna Bozeman, Sharon K. Davis … (2011)

In accordance with WHO guidelines, people with HIV infection in Botswana receive daily isoniazid preventive therapy against tuberculosis without obtaining a tuberculin skin test, but duration of prophylaxis is restricted to 6 months. We aimed to assess effectiveness of extended isoniazid therapy. In our randomised, double-blind, placebo-controlled trial we enrolled adults infected with HIV aged 18 years or older at government HIV-care clinics in Botswana. Exclusion criteria included current illness such as cough and an abnormal chest radiograph without antecedent tuberculosis or pneumonia. Eligible individuals were randomly allocated (1:1) to receive 6 months' open-label isoniazid followed by 30 months' masked placebo (control group) or 6 months' open-label isoniazid followed by 30 months' masked isoniazid (continued isoniazid group) on the basis of a computer-generated randomisation list with permuted blocks of ten at each clinic. Antiretroviral therapy was provided if participants had CD4-positive lymphocyte counts of fewer than 200 cells per μL. We used Cox regression analysis and the log-rank test to compare incident tuberculosis in the groups. Cox regression models were used to estimate the effect of antiretroviral therapy. The trial is registered at ClinicalTrials.gov, number NCT00164281. Between Nov 26, 2004, and July 3, 2009, we recorded 34 (3·4%) cases of incident tuberculosis in 989 participants allocated to the control group and 20 (2·0%) in 1006 allocated to the continued isoniazid group (incidence 1·26% per year vs 0·72%; hazard ratio 0·57, 95% CI 0·33-0·99, p=0·047). Tuberculosis incidence in those individuals receiving placebo escalated approximately 200 days after completion of open-label isoniazid. Participants who were tuberculin skin test positive (ie, ≥5 mm induration) at enrolment received a substantial benefit from continued isoniazid treatment (0·26, 0·09-0·80, p=0·02), whereas participants who were tuberculin skin test-negative received no significant benefit (0·75, 0·38-1·46, p=0·40). By study completion, 946 (47%) of 1995 participants had initiated antiretroviral therapy. Tuberculosis incidence was reduced by 50% in those receiving 360 days of antiretroviral therapy compared with participants receiving no antiretroviral therapy (adjusted hazard ratio 0·50, 95% CI 0·26-0·97). Severe adverse events and death were much the same in the control and continued isoniazid groups. In a tuberculosis-endemic setting, 36 months' isoniazid prophylaxis was more effective for prevention of tuberculosis than was 6-month prophylaxis in individuals with HIV infection, and chiefly benefited those who were tuberculin skin test positive. US Centers for Disease Control and Prevention and US Agency for International Development. Copyright © 2011 Elsevier Ltd. All rights reserved.

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Evolution of tuberculosis control and prospects for reducing tuberculosis incidence, prevalence, and deaths globally.

C Watt, M Raviglione, Christopher Dye … (2005)

The United Nations Millennium Development Goals (MDGs) are stimulating more rigorous evaluations of the impact of DOTS (the WHO-recommended approach to tuberculosis control based on 5 essential elements) and other possible strategies for tuberculosis (TB) control. To evaluate the prospects for detecting 70% of new sputum smear-positive cases and successfully treating 85% of these by the end of 2005, for reducing TB incidence, and for halving TB prevalence and deaths globally between 1990 and 2015, as specified by the MDGs. TB case notifications (1980-2003) from DOTS and non-DOTS programs and cohort treatment outcomes (1994-2002) reported annually to the World Health Organization (WHO) by up to 200 countries, TB death registrations, and prevalence surveys of infection and disease. Case notification series that reflect trends in incidence, treatment outcomes from DOTS cohorts, death statistics from countries with WHO-validated vital registration systems, and national prevalence surveys of infection and disease. Case reports, treatment outcomes, prevalence surveys, and death registrations from WHO's global TB database covering 1990-2003 to estimate TB incidence, prevalence, and death rates through 2015 for 9 epidemiologically different world regions. TB incidence increased globally in 2003, but incidence, prevalence, and death rates were approximately stable or decreased in 7 of 9 regions. The exceptions were regions of Africa with low ( or =4%) of HIV infection. The global detection rate of new smear-positive cases by DOTS programs increased from 11% in 1995 to 45% in 2003 (with the lowest case-detection rates in Eastern Europe and the highest rates in the Western Pacific) and could reach 60% by 2005. More than 17 million patients were treated in DOTS programs between 1994 and 2003, with overall treatment success rates more than 80% since 1998. In 2003, overall reported treatment success was 82%, with much variation among regions. The highest rates were reported in the Western Pacific region (89%) and lowest rates in African countries with high and low HIV infection rates (71% and 74%, respectively), in established market economies (77%), and in Eastern Europe (75%). To halve the prevalence rate by 2015, TB control programs must reach global targets for detection (70%) and treatment success (85%) and also reduce the incidence rate by at least 2% annually. To halve the death rate, incidence must decrease more steeply, by at least 5% to 6% annually. Reduction of TB incidence, prevalence, and deaths by 2015 could be achieved in most of the world, but the challenge will be greatest in Africa and Eastern Europe.

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Author and article information

Contributors

David W. Dowdy: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS ONE

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection: 2013

Publication date (Electronic): 4 April 2013

Volume: 8

Issue: 4

Electronic Location Identifier: e59546

Affiliations

[1 ]Internal Medicine Post-Graduation Program, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

[2 ]Social Medicine Institute, State University of Rio de Janeiro, Rio de Janeiro, Brazil

[3 ]Fernandes Figueira Institute, Fiocruz, Rio de Janeiro, Brazil

[4 ]Health Education M.Sc, Gama Filho University, Rio de Janeiro, Brazil

[5 ]Santa Casa de Misericórdia do Rio de Janeiro Hospital, Paschoal Granato Laboratory, Rio de Janeiro, Brazil

[6 ]Montreal Chest Institute, McGill University, Montreal, Quebec, Canada

Johns Hopkins Bloomberg School of Public Health, United States of America

Author notes

* E-mail: ricardo.steffen@ 123456gmail.com

Competing Interests: The authors have declared that no competing interests exist.

Helped with Data Collection: DC RF MB. Conceived and designed the experiments: RS MP AT RC. Performed the experiments: RS MP. Analyzed the data: RS MP AT DM. Contributed reagents/materials/analysis tools: STA DC RF MB. Wrote the paper: RS AT.

Article

Publisher ID: PONE-D-12-09634

DOI: 10.1371/journal.pone.0059546

PMC ID: 3617186

PubMed ID: 23593145

SO-VID: bd66f374-fa07-4dca-8952-d55e5831a5f2

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 2 April 2012

Date accepted : 19 February 2013

Page count

Pages: 8

Funding

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq [558383/2009-2]; Fundação de Amparo à Pesquisa do Rio de Janeiro – FAPERJ [E-26/ 102.712/2008]; and by the International Clinical, Operational and Health Services Research Training Award grant – ICOHRTA [5U 2R TW006883-02]. DC, RF and MB have a grant by CNPq/PIBIC UGF. The parental 4R vs 9H RCT is funded by the Canadian Institute of Health Research. None of the funding agencies is responsible for the statements in this article. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Cost-Effectiveness of Quantiferon®-TB Gold-In-Tube Versus Tuberculin Skin Testing for Contact Screening and Treatment of Latent Tuberculosis Infection in Brazil

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Abstract

Background

Methodology/Principal Findings

Conclusions

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PLOS Climate

Most cited references 36

Systematic review: T-cell-based assays for the diagnosis of latent tuberculosis infection: an update.

6-month versus 36-month isoniazid preventive treatment for tuberculosis in adults with HIV infection in Botswana: a randomised, double-blind, placebo-controlled trial.

Evolution of tuberculosis control and prospects for reducing tuberculosis incidence, prevalence, and deaths globally.

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