IGRAs: Among the blind the one-eyed is king 2nd symposium about IGRAs Special Session World Tuberculosis Day. 21st of March 2013 Barcelona. Catalonia. Spain
J. Domínguez Servei Microbiologia. Institut d’Investigació Germans Trias i Pujol Badalona, Barcelona. ([email protected]) Brief history
2000
Nil Avian Human Mitogen Control PPD PPD Control
Stimulating antigens: human PPD and avian PPD Brief history
T-SPOT.TB Tuberculin skin testing QuantiFERON-TB Gold In Tube
2002
Moving LTBI diagnosis from clinical departments to laboratory. Comparison between TST and IGRAs
Domínguez J. Actas Derm-Sifil. 2012 Domínguez J. 2009 First day T-SPOT.TB QFN-G-IT Exp Rev Resp Med.
Collection of blood sample (8ml) Collection of blood sample
and centrifugation (3ml) in QFN tubes containing
MTB antigens
Isolation of PBMCs and washing No hands
Count PBMCs using a -
on time for 1 sample for 1 time on on time on
- counting chamber
on time for 20 samples 20 time on for
-
Addition of 250,000 cells per well
4 h hands h 4 with the MTB specific antigens 1/2 hour (h) hands (h) hour 1/2
Overnight incubation Overnight incubation
Second day
Centrifugation of tubes
to harvest the IFN-gamma released for 1 to 20samples
1 1 h hands
on on for time ELISPOT ELISA
-
-
on time time on
1 to 20 samples samples 20 to 1
1 h hands h 1 Count spots by naked eye or using a plate reader Read the concentration of IFN-gamma by means of an automated reader Correlation with latent TB infection
Domínguez J. CVI. 2008 BCG vaccination effect
Domínguez J. CVI. 2008 Correlation with risk factors
De Souza-Galvão M. IJTLD. Submitted 2013 Marker of progression
TBNET Study # 2 Use of interferon- release assays as a predictor for the progression from latent infection with M. tuberculosis to tuberculosis in a European cohort
Positive IGRA Negative IGRA Indet IGRA (n=642) (n=1792) (n=11)
Offered chemo and accepted 306 (TB n=6) 18 (TB n=0) 1 (TB n=0)
No chemotherapy 335 (TB n=20) 1774 (TB n=4) 10 (TB n=0) Offered, not accepted 170 (TB n=3) 10 (TB n=0) 1 (TB n=0)
Not offered chemotherapy 165 (TB n=17) 1764 (TB n=4) 9 (TB n=0) Positive and negative predictive value
Altet N. Submitted 2013 668 Contacts Follow-up during 30 months
284 286 98 No LTBI LTBI QFN & TST negatives TST positive and/or TST & QFN negatives, Primary prophylaxis or positives but no QFN positive (in all cases a negative result was obtained two moths later) candidates x prophylaxis Prophylaxis
QFN-G-IT PT • VPP=15% • VPP = 3% • VPN=100% • VPN = 99% 8 active TB
PPV and NPV of the TST and IGRAs for the development of tuberculosis
Test PPV NPV
TST 2.3-3.3 99.7
QFN-G-IT 2.8-14.3 99.8
T-SPOT.TB 3.3-10.0 97.8
Diel R. Eur Respir J. 2011 Positive and negative predictive value
Diel R. AJCCM 2010 Positive and negative predictive value
The PPV using commercial IGRAs was 2.7%, in comparison with 1.5% of the TST (P<0.0001)
The PPV increased to 6.8% and 2.4% The NPV for the IGRAs was 99.7%, for IGRAs and TST, respectively, and 99.4% for the TST when were only considered high-risk groups (P=0.01) (P=0.0001) Pediatric population
There was no clear evidence that IGRAs should replace TST for detecting LTBI in children. Sensitivity of the IGRA for TB disease was no different from TST. Indeterminate results in young children
Kampmann B. ERJ 2009 Pediatric population
Altet N. ERJ. 2011. NTM effect
TBNET Study#22: Evaluation of non-tuberculous mycobacteria effect in the tuberculosis infection diagnosis
Stimulation with M.avium sensitins
91 non-BCG-vaccinated children with positive TST and negative T-SPOT.TB 33 positives
Stimulation with GPLs of M.avium serovar 4
6 non-BCG-vaccinated children with positive TST and negative T-SPOT.TB 6 positives and positive sensitin result
Latorre I. ERJ. 2010 Immunosuppressed patients
Mínguez S. Clin Rheumatol.2012 Vilavella M. Clin Exp. Dermatol Submitted. 2013 Latorre I. ERJ. Submitted. 2013 HIV patients
T-SPOT QFN TST Positive 7 5 5 Negative 58 60 62 Indet. 2 2 0 67 67 67
Latorre I. BMC Infect Dis 2010 Predictive value in HIV patients
Aichelburg. CID 2009 Predictive value in HIV patients
TBNET Study #1: TIGRA in immunocompromised patients
T-SPOT.TB QFN-G-IT TST
test N At risk TB inc N At risk TB inc N At risk TB inc
pos 96 168.6 3 1.78 92 152.6 2 1.31 60 92.2 3 3.25
neg 529 892.8 3 0.34 612 1036 2 0.19 659 1118 3 0.27
Current evidence suggests that IGRAs perform similarly to the TST at identifying HIV-infected individuals with LTBI. Both tests have modest predictive value and suboptimal sensitivity. Predictive value in patients with psoriasis
Laffitte E et al. studied 50 patients with psoriasis. In all cases TST and T- SPOT.TB were performed. Any of the 38 patients with negative T-SPOT.TB without prophylasis developed active TB in the following 4 years.
Garcovich S et al. studied 50 patients with TST and QFN-G-IT. No patient with negative QFN-G-IT and normal RX normal received treatment, and any of them developed TB in the following 18 months.
Chiu HY et al. performed QFN-G in 110 patients with psoriasis that received biological treatment, being the test positive in 12 cases. Only 4 patients with positive QFN-G received treatment. From the overall population included in the study, only one patient developed active TB. It was a patient with a positive QFN but rejected prophylaxis. Immunosuppressed patients
TBNET Study #1: TIGRA in immunocompromised patients
No major differences within IGRA. Test performance and test interpretation varies with underlying immunodeficiency • Overall level of positive tests • Relation to risk factors for exposure Similarities in immunodeficiencies primarily affecting T- cells (HIV, SOT, SCT) Implications for risk assessment Not high NVP Diagnosing active TB
Latorre I. DMID 2009 Diagnosing active TB
NOT USEFUL To rule-out active TB IGRAs in BAL Within-Subject Variability and Boosting Effect
Van Zyl-Smit. PlosOne.2009 Health Care Workers
Useful for diagnosing recent infection Serial testing: conversion and reversions Casas I. PlosOne. 2009 Technical improvements: T Cell Extend
T Cell Extend: allows delay the T-SPOT.TB performance 32h Latorre I. J.Infection. Submitted 2013 Technical improvements: IGRAs on paper
IP-10 ELISA & QFN-G-IT en Barcelona Filter paper by postal mail IGRAs on paper in Conpenhagen
Filter paper
ELISA IGRAs on paper
Filter paper
Plasma
Ruhwald M & Study Group Control Group Domínguez J. ERJ 2013. Guidelines
GUIA MANEJO IGRAS SEIMC-SEPAR
2008 2012 Coming soon (2013) Summary
• Exposure and risk factor association • Higher specificity (no affected by BCG) • Reduce the unnecessary prophylaxis • PPV similar than TST and very good NPV in immunocompetents • Less affected by immunosuppressor treatments • Rule-out active TB using blood samples • Diagnosing active TB in non-blood samples • Guidelines • Cost-effective • IGRAs inspire confidence in patients Conclusions
Lasting tuberculosis immune response versus Latent tuberculosis infection
“TST and IGRAs measure the same wrong thing, but IGRAs in a more specific way” Hans Rieder ANNUAL MEETING 2013 Barcelona. Catalonia. Spain September 6th, 2013