Use of Quantiferon-TB-Gold in Tube ® test for detecting latent tuberculosis in patients considered as candidates for anti-TNF therapy in routine clinical practice

Background/methods Quantiferon-TB-Gold in Tube® test (QFT-G-IT) may have advantages if combined with TST when screening for Latent Tuberculosis Infection (LTBI) prior to initiating anti-TNF therapy in an area of intermediate tuberculosis incidence such as Spain. In a small-scale prospective study, we evaluate the use of QFT-G-IT in combination with the screening recommended in Spain (Tuberculin-Skin Test, TST retest, clinical data, and Chest X-Ray (CXR)) for LTBI in patients considered as candidates for anti-TNF a treatment. Results From June 2008 to October 2010, 123 patients from a 300-bed hospital in Palma de Mallorca (Spain) were included in the study. The majority of patients were under immunosuppressive therapy. A positive TST and TST booster were found in 22 and 17 patients, respectively. Thus 39 (31.7%) of the 123 patients had a positive TST. QFT-G-IT was positive in 16 patients (13.6%), indeterminate in 4 (3.2%), and negative in 103 (83.7%). One of the two tests was positive and LTBI was diagnosed in 34.1% of patients. The agreement between TST and QFT-G-IT among vaccinated patients was low and not statistically significant (Kappa=0.15) and was almost perfect among non-BCG vaccinated patients (K=0.81). TST positive responses were significantly related to BCG-vaccination (p<0.05) and QFT-G-IT positive response rates were related to older age (p<0.05).Conclusion QFT-G-IT may have advantages when combined with TST in immune suppressed patients especially in older patients with a negative TST; in BCG vaccinated patients with a positive TST, QFT-G-IT could avoid unnecessary treatments and toxicities related to a false-positive TST result (AU)

Introducción/método Quantiferon-TB-Gold in Tube® (QFT-G-IT) en combinación con la Prueba de la tuberculina (PT) puede ser útil para el diagnóstico de infección tuberculosa latente (ITL) en pacientes candidatos a tratamiento con anti-TNF en un país de incidencia intermedia de tuberculosis como España. Se evalúa en un estudio piloto prospectivo QFT-G-IT en combinación con las pruebas recomendadas en España (PT, PT-booster, datos clínicos y radiografía de tórax) para el diagnóstico de ITL en pacientes con enfermedades inmunológicas candidatos a tratamiento con fármacos anti-TNFa. Resultados Se incluyeron 123 pacientes desde junio de 2008 a octubre de 2010 en el hospital Son Llàtzer de Palma de Mallorca. La PT inicial y la PT booster fueron positivas en 22 y 17 pacientes, respectivamente, el 31,6% tuvo una PT positiva, QFT-G-IT fue positivo en 16 (13,6%), indeterminado en 4 (3,2%) y negativo en 103 pacientes (83,7%). En 34,1% al menos uno de los dos tests fue positivo y se diagnosticó ITL. La concordancia entre PT y QFT-G-IT fue baja en pacientes vacunados con BCG (Kappa=0,15) y excelente en no vacunados con BCG (K=0,81). La positividad de la PT se relacionó con la vacunación con BCG (p<0.05) y la de QFT-G-IT con una mayor edad (p<0.05).Conclusión El uso de QFT-G-IT puede optimizar el diagnóstico de ITL en estos pacientes especialmente en los más añosos con una PT negativa. En pacientes vacunados de BCG con una PT positiva, QFT-G-IT podría evitar tratamientos innecesarios de ITL relacionados con un falso positivo (AU)

Use of Quantiferon-TB-Gold in Tube(®) test for detecting latent tuberculosis in patients considered as candidates for anti-TNF therapy in routine clinical practice.

BACKGROUND/METHODS: Quantiferon-TB-Gold in Tube(®) test (QFT-G-IT) may have advantages if combined with TST when screening for Latent Tuberculosis Infection (LTBI) prior to initiating anti-TNF therapy in an area of intermediate tuberculosis incidence such as Spain. In a small-scale prospective study, we evaluate the use of QFT-G-IT in combination with the screening recommended in Spain (Tuberculin-Skin Test, TST retest, clinical data, and Chest X-Ray (CXR)) for LTBI in patients considered as candidates for anti-TNFα treatment. RESULTS: From June 2008 to October 2010, 123 patients from a 300-bed hospital in Palma de Mallorca (Spain) were included in the study. The majority of patients were under immunosuppressive therapy. A positive TST and TST booster were found in 22 and 17 patients, respectively. Thus 39 (31.7%) of the 123 patients had a positive TST. QFT-G-IT was positive in 16 patients (13.6%), indeterminate in 4 (3.2%), and negative in 103 (83.7%). One of the two tests was positive and LTBI was diagnosed in 34.1% of patients. The agreement between TST and QFT-G-IT among vaccinated patients was low and not statistically significant (Kappa=0.15) and was almost perfect among non-BCG vaccinated patients (K=0.81). TST positive responses were significantly related to BCG-vaccination (p<0.05) and QFT-G-IT positive response rates were related to older age (p<0.05). CONCLUSION: QFT-G-IT may have advantages when combined with TST in immunosuppressed patients especially in older patients with a negative TST; in BCG vaccinated patients with a positive TST, QFT-G-IT could avoid unnecessary treatments and toxicities related to a false-positive TST result.