Tuberculin skin test and ELISPOT/T. SPOT.TB in children and adolescents with juvenile idiopathic arthritis.

BACKGROUND: There are controversies regarding the accuracy of the tuberculin skin test (TST) and methods based on the production of interferon gamma by sensitized T cells for the diagnosis of latent tuberculosis infection (LTBI) in pediatrics and immunosuppressed patients. Our objectives are to study TST and ELISPOT/T. SPOT.TB in the diagnosis of LTBI in children and adolescents with JIA undergoing methotrexate, the correlation between both and the sensitivity and specificity of T. SPOT.TB. METHODS: This is an observational prospective longitudinal study in which children and adolescents with JIA undergoing methotrexate therapy were assessed for clinical and epidemiological data for LTBI, in addition to performing TST and T. SPOT.TB at baseline and after 3 and 12months. RESULTS: There were 24 patients. The prevalence of LTBI at inclusion was 20.8%, the incidence after initiation of immunosuppressions 26.3% and the prevalence at the end of the study 41.6%. Epidemiological history positive for TB showed a relative risk of 2.0 for the development of LTBI. Only 2 patients had positive T. SPOT.TB but only in one it was useful for detecting early LTBI. T. SPOT.TB presented a sensitivity of 10%, specificity of 92.8%, and low correlation with TST. No patient developed TB disease at a mean follow-up of 47months. CONCLUSIONS: We found a high prevalence of ILTB that doubled with immunosuppression and that epidemiological history was an important relative risk. T. SPOT.TB showed low sensitivity and high specificity, and no superiority over TST. There was low agreement and little influence of immunosuppression on the results of both tests.

The challenge of pediatric tuberculosis in face of new diagnostic techniques.

OBJECTIVES: To present an updated review concerning new assays for diagnosing tuberculosis based on in vitro interferon-gamma production by host T cells, and compare them with tuberculin skin test. METHODS: A literature review was carried out based on Medline and LILACS databases (2000-2008) searching for the following keywords: tuberculosis, interferon-gamma, quantiFERON, ELISPOT and T-SPOT.TB. RESULTS: These new assays proved to have, in general, equal or superior sensitivity and specificity than the tuberculin skin test not only in adults but also in children and immunosuppressed patients for the diagnosis of both latent tuberculosis infection or active disease, with some advantages such as less cross-reactivity as a result of previous BCG vaccination, less influence of anergy and better accuracy in small children. In the United States, these assays have been used instead of the tuberculin skin test and, although still very expensive, the World Health Organization will be making its economic viability a priority. CONCLUSIONS: Always having in mind the importance of clinical and epidemiological histories, these new assays based on interferon-gamma release present promising results and should be considered in tuberculosis investigation procedures for all patients, however with a special concern in the risk groups (i.e., children and immunosuppressed patients).

O desafio da tuberculose na faixa etária pediátrica frente a novas técnicas diagnósticas: [revisão] / The challenge of pediatric tuberculosis in face of new diagnostic techniques: [review]

OBJETIVOS: Apresentar uma revisão atualizada sobre os novos métodos para o diagnóstico da tuberculose baseados na produção in vitro de interferon-gama (IFN-γ) por células T dos pacientes sob investigação, comparando-os com a tradicional prova tuberculínica. FONTES DOS DADOS: Revisão de literatura utilizando os bancos de dados MEDLINE e LILACS (2000-2008) utilizando as palavras-chave tuberculose, interferon-gama, quantiFERON, ELISPOT e T-SPOT.TB. SÍNTESE DOS DADOS: Esses novos testes mostraram-se, de um modo geral, tão ou mais sensíveis e específicos que a prova tuberculínica, tanto em adultos como em crianças e imunossuprimidos, para o diagnóstico da infecção latente e da doença ativa, apresentando vantagens como a menor interferência da vacinação prévia pelo BCG, menor influência de estados anérgicos e melhor acurácia em crianças menores. Nos Estados Unidos, já estão sendo utilizados em substituição à prova tuberculínica, e apesar dos custos ainda elevados, a Organização Mundial de Saúde vai priorizar a sua viabilidade econômica. CONCLUSÕES: Sempre levando em conta a importância da história clínica e epidemiológica, os novos testes baseados na produção de IFN-γ apresentam resultados promissores e deverão ser considerados na investigação de tuberculose em qualquer paciente, mas especialmente nos grupos de risco, como as crianças e os imunossuprimidos.

OBJECTIVES: To present an updated review concerning new assays for diagnosing tuberculosis based on in vitro interferon-gamma production by host T cells, and compare them with tuberculin skin test. SOURCES: A literature review was carried out based on Medline and LILACS databases (2000-2008) searching for the following keywords: tuberculosis, interferon-gamma, quantiFERON, ELISPOT and T-SPOT.TB. SUMMARY OF THE FINDINGS: These new assays proved to have, in general, equal or superior sensitivity and specificity than the tuberculin skin test not only in adults but also in children and immunosuppressed patients for the diagnosis of both latent tuberculosis infection or active disease, with some advantages such as less cross-reactivity as a result of previous BCG vaccination, less influence of anergy and better accuracy in small children. In the United States, these assays have been used instead of the tuberculin skin test and, although still very expensive, the World Health Organization will be making its economic viability a priority. CONCLUSIONS: Always having in mind the importance of clinical and epidemiological histories, these new assays based on interferon-gamma release present promising results and should be considered in tuberculosis investigation procedures for all patients, however with a special concern in the risk groups (i.e., children and immunosuppressed patients).