Assessment of T-SPOT-TB test for the diagnosis of latent tuberculosis infection in patients with psoriasis / Avaliação do teste T-SPOT.TB no diagnóstico de infecção tuberculosa latente em pacientes com psoríase

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Introduction: The therapy for psoriasis was modified by the introduction of immunebiological products that allow better disease control and better quality of life for patients, but promotes increased risk forf latent tuberculosis, requiring diagnosis shortly before its establishment. Purpose: To assess the performance of T-SPOT.TB test for the diagnosis of latent tuberculosis infection in patients with psoriasis. Methods: Within a experimental, prospective, analytic, clinical assay type study, with comparison of groups, to validate a diagnostic test, 33 patients with psoriasis (psoriasis group) and 30 patients with other dermatological diseases (basis group), attempted at General Dermatology and Psoriasis Out-patients Departments of Recifes Dermatological Studies Center of Santa Casa de Misericórdia, from February to November 2009, were submitted to PPD and TSPOT. TB tests. For both groups, we admitted 18 years as minimal age for inclusion. The exclusion criteria included disease ou physiological conditions that compromised immunological competence, except psoriasis to psoriasis group. We used Mantoux technique for PPD test and a simplified variant of Enzyme-Linked Immunospot technique to determine effector T cells, secretors of IFN-g in response to M. tuberculosis specific antigens, to T-SPOT.TB test. Dependent variables were the results of T-SPOT.TB test against ESAT-6 and CPF-10 antigens, and the results to PPD test, considering enduration of 0-4 mm as non reactor; 5-10 mm weak reactor and ≥ 10 mm, strong reactor. Independent variables were age, sex, skin color, psoriasis evolution time, occupation, history of intradomiciliar contact and income, alcoolism and disease grade. Three models, comparing T-SPOT.TB test to PPD test, intradomiciliar contact and both, were submitted to Qui Squared test or Exact Fisher Test, at significance level of 0.05, as well as to Mantel- Haenszel test. The research has been approved by Ethics Committee of Universidade Federal de Pernambuco e Universidade de São Paulo. Results: Psoriasis group differed from base group on sex ratio with predominance of male gender (rate=0.7:1; p=0,047), major mean age (42,1 ± 1.9 years against 34,1 ± 1.4 years in basic group, p = 0,023) phototypes I and II (p = 0,020); lower scholarship, income and less frequent intradomiciliar contact with tuberculosis (p = 0,001). The groups also differed on the positivity of PPD test (greater in base group; p = 0,001). T-SPOT.TB test had sensibility and specificity of 9,1% and 95.5%, in model 1; 27,3% and 60%, in model 2, and values of 60% and 53,3% respectively in model 3. Model 1 showed greater concordance and highest value of Odds Ratio test weighted by Mantel-Haenszel test, having these two parameters statistical significance when compared to the other two models. Conclusions: T-SPOT.TB test had great ability to diagnose negative cases for latent tuberculosis, and constitutes an option for screening patients to immunobiological therapy administration.

ASSUNTO(S)

immunossupression imunossupressão therapeutic terapêutica latent tuberculosis tumoral necrosis factor psoríase fator de necrose tumoral tuberculose latente psoriasis

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