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Utility and Performance of IGRA for Community-based TB Infection Screening in Vietnam

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Luan Nguyen Quang Vo

Friends for International TB Relief; Viet Nam

WHO Collaboration Centre on Tuberculosis and Social Medicine, Karolinska Institutet; Sweden

@UNIONCONFERENCE�@FIT_eV

worldlunghealth.org�tbhelp.org

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CONFLICT OF INTEREST DISCLOSURE FORM

☐ I have no Conflict of Interest to report. 

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☐ I have the following Conflict of Interest(s) to report: 

Please tick the type of affiliation / financial interest and specify the name of the organisation:

☐ Receipt of grants/research supports: Stop TB Partnership, European Commission

☐ Receipt of honoraria or consultation fees: Qiagen

☐ Participation in a company sponsored speaker’s bureau:

☐ Tobacco-industry and tobacco corporate affiliate:

☐ Stock shareholder: Johnson & Johnson

☐ Spouse/partner:

☐ Other: 

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✔

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THE CASE FOR URGENCY

BACKGROUND

Global ~1.65% p.a.

United States

2012

2100

2200

Viet Nam (National Strategy 2030)

2030

Viet Nam (2014) ~2.60% p.a.

Sources: Adapted from Nicholson A, Zero TB Initiative : Strategies to Eliminate Tuberculosis One Community at a Time.

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THE VALUE OF INTEGRATING PREVENTION

BACKGROUND

Impact of comprehensive TB interventions(a)

Resource needs by cost category

Notes: (a) Illustrative example for Kenya.

Sources: Stop TB Partnership. The Global Plan to End TB 2023-2030. Geneva, Switzerland; 2022.

Integrating TBI test & treat seems impactful…

…with manageable marginal costs

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TBI testing

THEORETICAL FRAMEWORK & PRACTICAL APPLICATION

BACKGROUND

Sources: World Health Organization. Consolidated guidelines on tuberculosis : Module 1 : Prevention. Geneva, Switzerland; 2020.

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  • Aim: Assess assessed the feasibility of using interferon-γ release assays (IGRAs) at lower healthcare levels and the comparative performance of 3-month and 9-month daily TPT regimens (3HR/9H)
  • Objectives:
    • Measure the positivity and indeterminate rates of QFT Plus
    • Measure the TPT initiation and completion rate
  • Additional objective:
    • Quantify the comparative attrition in persons with TBI due to operational challenges of deploying QFT Plus and TST at the primary & secondary care levels‡

AIM & OBJECTIVES

METHODS

Sources: ‡ Vo LNQ, Tran TTP, Pham HQ, Nguyen HT, Doan HT, Truong HT, et al. Comparative performance evaluation of QIAreach QuantiFERON-TB and tuberculin skin test for diagnosis of tuberculosis infection in Viet Nam. Sci Rep. 2023;13:15209.

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  • Design: Longitudinal cohort study from May-2019 to Sep-2020
  • Setting: Embedded into routine contact tracing at commune PHC centers and community TB ACF events in 8 districts of Hai Phong & Ho Chi Minh City
  • Participants:
    • Household contacts (HHC) ≥5 years
    • Primary- and secondary-level healthcare workers (HCW)
    • Vulnerable community members, e.g., elderly ≥55 years, urban poor, economic migrants
    • Present for health check, reside in district, consent to participate
  • Recruitment: Consecutive at community TB screening events or HHC investigations at PHC centers w/ follow-up throughout TPT

STUDY DESIGN, SETTING AND SAMPLE

METHODS

Hai Phong

Ho Chi Minh City

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SPECIMEN COLLECTION & PROCESSING PROCEDURE

METHODS

All attendants systematically screened for TB symptoms & CXR to rule out active TB

Abnormal CXR or clinical suspicion referred for sputum test per national TB guidelines

Remaining attendants invited to participate; four tubes collected from consenting individuals

Immediately shaken ~10 times and stored inside dry ice coolers at 17°C–25°C

Transported to the provincial lung hospitals two times per day (within 6 hours)

Incubation and ELISA as per manufacturer recommendations

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TB INFECTION CARE CASCADE

RESULTS

Sources: Aggregate TB infection care cascade. LTBI, latent TB infection; LTFU, loss to follow- up; QFT- Plus, QuantiFERON- TB Gold Plus assay; TB, tuberculosis; TPT, TB preventive therapy.

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RESULTS

SAMPLE CHARACTERISTICS

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RESULTS

ASSOCIATION WITH QFT-PLUS POSITIVITY

Higher adjusted odds ratio of QFT-positivity

Lower adjusted odds ratio of QFT-positivity

Covariate

aOR‡

P-value

Covariate

aOR‡

P-value

Being male

1.51 [1.28, 1.78]

<0.001

<15 years¥

0.18 [0.13, 0.26]

<0.001

45–59 years¥

1.30 [1.05, 1.60]

0.018

15-29 years¥

0.56 [0.42, 0.75]

<0.001

Abnormal CXR§

2.23 [1.38, 3.61]

0.001

HCW

0.34 [0.24, 0.48]

<0.001

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Peri-urban

0.55 [0.36, 0.85]

0.007

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No CXR§

0.28 [0.15, 0.51]

<0.001

Notes: ‡ Saturated, mixed-effect logistics model with study district as the random effect; ¥ Reference: 30–44 years; § Reference: Normal CXR; ¶ Reference: Vulnerable community members.

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BREAKDOWN BY SITE & GROUP

RESULTS

  • QFT+ variation reflects local burden
    • Similar in HHC
    • Significant difference in vulnerable groups
  • Low QFT+ in HCW
  • Substantial pre-TPT loss to follow-up: 30%-40%
  • Only 36%-58% of eligible persons complete TPT

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IMPACT OF OPERATIONAL BARRIERS AT

POC AND NEAR-POC

RESULTS

  • Operational losses, QFT vs. TST
    • QFT indeterminate: 6.1% (17/278)
    • TST decline/pre-read LTFU: 23.8% (62/261)
  • TST attrition in PW/TBI: 28.8%(19/66)
    • 16.7% (11/66) due to declining TST
    • 12.1% (8/66) due to pre-read LTFU
  • QFT attrition in est. PW/TBI: 0.7% (2/278)
  • 33.3% (22/66) attrition in PW/TBI due to discordance (QFT+, TST-)
    • Overall concordance: 75.5% (151/200)
  • Overall attrition in PW/TBI: 62.1% (41/66)
  • Combined attrition in PW/TBI: 63.2% (43/68)

Sources: Vo LNQ, Tran TTP, Pham HQ, Nguyen HT, Doan HT, Truong HT, et al. Comparative performance evaluation of QIAreach QuantiFERON-TB and tuberculin skin test for diagnosis of tuberculosis infection in Viet Nam. Sci Rep. 2023;13:15209.

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Measured by positivity and indeterminate rates, it is feasible to employ QFT Plus at the POC and near-POC level, but IGRA rollout requires careful preparation and monitoring to ensure quality and sustainability

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Operational challenges can cause substantial attrition in PW/TBI and represent a significant inefficiency at the POC and near-POC

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There is substantial pre-treatment loss to follow-up as one in three persons with TBI declined TPT with no discernable pattern across vulnerable groups

DISCUSSION

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Nevertheless, our study furnishes further evidence for the decentralization of services to the community and lower care levels to promote the scale-up of TB infection testing and treatment towards ending TB

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  • Collaborators: National TB Program, the provincial lung hospitals in Hai Phong and Ho Chi Minh City and the district and commune public health staff
  • Funding: Data collection was paid by the European Commission’s Horizon 2020 programme and Stop TB Partnership’s TB REACH initiative with support from Global Affairs Canada. Test kits were provided by Qiagen. The sponsors had no involvement in the design of the study or the interpretation of the results.
  • Participants: All persons with TB infection, who have generously contributed their time and efforts in support of this work

ACKNOWLEDGEMENTS

The IMPACT TB project was funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 733174

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��Thank you for �your attention!���

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