Estimação da Sensibilidade e Especificidade de Testes Diagnósticos da Brucelose Bovina via lnferência Bayesiana
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Data
2014-10-22
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Universidade Federal de Viçosa
Resumo
A brucelose é uma doença infectocontagiosa provocada por bactérias do gênero Brucella que produz infecção característica nos animais, podendo contaminar o homem. Os testes para diagnóstico da brucelose utiIizados no Brasil são reaIizados a partir de amostras obti- das em animais com suspeita da enfermidade abatidos ou mortos na propriedade. No país são poucos os estudos de vaIidação de testes diagnósticos para brucelose que apresentam metodologias estatísticas para a estimação da sensibilidade e da especificidade satisfatori- amente. Neste trabalho, empregou a metodologia proposta por Joseph, Gyorkos e Coupal (1995) para obter estimativas da sensibilidade e da especificidade do teste de triagem Antígeno Acidificado Tamponado (AAT) e dos testes confirmatórios Mercaptoetanol (2- ME) e Diagnóstico Bacteriológico (DBac), testes estes, em conformidade ao Programa Nacional de Controle e Erradicação da Brucelose e da Tuberculose Animal (PNCEBT) inserido no Brasil em 2001. De forma complementar, comparou-se as estimativas em três cenário distintos: quando dispõe do resultado de somente um teste; (ii) quando dispõe dos resultados de dois testes; e (iii) quando dispõe dos resultados de três testes. A amostra conteve 175 animais, obtida por conveniência a partir de material encaminhado, de todas as regiões do BrasiI, ao Laboratório de Diagnóstico de Doenças Bacterianas do LANAGRO-MG, entre os anos de 2008 a 2011. Os códigos para obter as estimativas foram impIementados no OpenBUGS, por meio do algoritmo Gibbs Sampler. Os resuIta- dos apontaram que a prevalência estimada para brucelose bovina em animais suspeitos é de 79%, ou seja, de cada 100 animais com suspeita da doença, 79 são diagnósticos como doentes. Em relação às medidas de desempenho, AAT se mostrou mais sensível para diagnosticar a Brucelose Bovina, o 2-ME mais Especifico para não diagnosticar a Brucelose Bovina e o DBac mostrou-se 100% específico para não diagnosticar a doença e menos sensível para diagnosticar a doença.
Brucellosis is an infectious and contagious disease caused by bacteria of the genus Bru- ceIIa. It produces a characteristic infection in animals and may aIso contaminate humans. The tests used for diagnosis of bruceIIosis in Brazil are conducted in samples obtained from animals suspected of having the disease, sIaughtered or that died at the farm. In Brazil there are few vaIidation studies of diagnostic tests for bruceIIosis presenting statistical methodologies for the estimation of sensitivity and Specificity satisfactorily. The present work used the methodology proposed by Joseph, Gyorkos e Coupal (1995) to obtain es- timates of sensitivity and Specificity of screening test Buffered Acidified Antigen (AAT) and confirmatory tests Mercaptoethanol (2-ME) and Bacteriological Diagnosis (DBAC), these tests are in accordance with the National Program for Control and Eradication of AnimaI Brucellosis and Tuberculosis (PNCEBT), which began in Brazil in 2001. The study was complemented with comparisons of the estimates in three different scenario: (i) when the resuIt of onIy one test is avaiIabIe (ii) when results of two test are avaiIabIe, and (iii) results of three tests. The data contained samples from 175 animaIs, obtained by convenience from material sent from aII regions of BraziI, to the Laboratory of Diag- nosis of Bacterial Diseases of LANAGRO-MG, between the years 2008-2011. Statistical computations and Gibbs Sampler algorithm were impIemented in OpenBUGS. Results showed that the estimated prevalence of bovine bruceIIosis in suspected animals is 79%, which means that for every 100 animals suspected of having the disease, 79 are diagnosed with it. Regarding performance measures, AAT was more sensitive for diagnosing Bovine BruceIIosis, 2-ME more Specific for not diagnosing Bovine Brucellosis and DBac showed 100% specific for not diagnosing the disease and Iess sensitive for diagnosing the disease.
Brucellosis is an infectious and contagious disease caused by bacteria of the genus Bru- ceIIa. It produces a characteristic infection in animals and may aIso contaminate humans. The tests used for diagnosis of bruceIIosis in Brazil are conducted in samples obtained from animals suspected of having the disease, sIaughtered or that died at the farm. In Brazil there are few vaIidation studies of diagnostic tests for bruceIIosis presenting statistical methodologies for the estimation of sensitivity and Specificity satisfactorily. The present work used the methodology proposed by Joseph, Gyorkos e Coupal (1995) to obtain es- timates of sensitivity and Specificity of screening test Buffered Acidified Antigen (AAT) and confirmatory tests Mercaptoethanol (2-ME) and Bacteriological Diagnosis (DBAC), these tests are in accordance with the National Program for Control and Eradication of AnimaI Brucellosis and Tuberculosis (PNCEBT), which began in Brazil in 2001. The study was complemented with comparisons of the estimates in three different scenario: (i) when the resuIt of onIy one test is avaiIabIe (ii) when results of two test are avaiIabIe, and (iii) results of three tests. The data contained samples from 175 animaIs, obtained by convenience from material sent from aII regions of BraziI, to the Laboratory of Diag- nosis of Bacterial Diseases of LANAGRO-MG, between the years 2008-2011. Statistical computations and Gibbs Sampler algorithm were impIemented in OpenBUGS. Results showed that the estimated prevalence of bovine bruceIIosis in suspected animals is 79%, which means that for every 100 animals suspected of having the disease, 79 are diagnosed with it. Regarding performance measures, AAT was more sensitive for diagnosing Bovine BruceIIosis, 2-ME more Specific for not diagnosing Bovine Brucellosis and DBac showed 100% specific for not diagnosing the disease and Iess sensitive for diagnosing the disease.
Descrição
Palavras-chave
Teoria bayesiana de decisão estatística, Estatística, Testes, Brucelose - Diagnóstico, Amostragem - Estatística, Bayesian statistical decision theory, Statistics, Tests, Brucellosis - Diagnosis, Sampling - Statistics
Citação
SOUZA, Márcio Rodrigues dos Santos. Estimation of Sensitivity and Specificity of Diagnostic Tests of Bovine Brucellosis via Bayesian lnference. 2014. 73 f. Dissertação (Mestrado em Estatística Aplicada e Biometria) - Universidade Federal de Viçosa, Viçosa, 2014.