PCR colorimetric dot-blot assay and clinical pretest probability for diagnosis of Pulmonary Tuberculosis in Smear-Negative patients

<p>Abstract</p> <p>Background</p> <p>Smear-negative pulmonary tuberculosis (SNPTB) accounts for 30% of Pulmonary Tuberculosis (PTB) cases reported annually in developing nations. Polymerase chain reaction (PCR) may provide an alternative for the rapid detection of <it>Mycobacterium tuberculosis </it>(MTB); however little data are available regarding the clinical utility of PCR in SNPTB, in a setting with a high burden of TB/HIV co-infection.</p> <p>Methods</p> <p>To evaluate the performance of the PCR dot-blot in parallel with pretest probability (Clinical Suspicion) in patients suspected of having SNPTB, a prospective study of 213 individuals with clinical and radiological suspicion of SNPTB was carried out from May 2003 to May 2004, in a TB/HIV reference hospital. Respiratory specialists estimated the pretest probability of active disease into high, intermediate, low categories. Expectorated sputum was examined by direct microscopy (Ziehl-Neelsen staining), culture (Lowenstein Jensen) and PCR dot-blot. Gold standard was based on culture positivity combined with the clinical definition of PTB.</p> <p>Results</p> <p>In smear-negative and HIV subjects, active PTB was diagnosed in 28.4% (43/151) and 42.2% (19/45), respectively. In the high, intermediate and low pretest probability categories active PTB was diagnosed in 67.4% (31/46), 24% (6/25), 7.5% (6/80), respectively. PCR had sensitivity of 65% (CI 95%: 50%–78%) and specificity of 83% (CI 95%: 75%–89%). There was no difference in the sensitivity of PCR in relation to HIV status. PCR sensitivity and specificity among non-previously TB treated and those treated in the past were, respectively: 69%, 43%, 85% and 80%. The high pretest probability, when used as a diagnostic test, had sensitivity of 72% (CI 95%:57%–84%) and specificity of 86% (CI 95%:78%–92%). Using the PCR dot-blot in parallel with high pretest probability as a diagnostic test, sensitivity, specificity, positive and negative predictive values were: 90%, 71%, 75%, and 88%, respectively. Among non-previously TB treated and HIV subjects, this approach had sensitivity, specificity, positive and negative predictive values of 91%, 79%, 81%, 90%, and 90%, 65%, 72%, 88%, respectively.</p> <p>Conclusion</p> <p>PCR dot-blot associated with a high clinical suspicion may provide an important contribution to the diagnosis of SNPTB mainly in patients that have not been previously treated attended at a TB/HIV reference hospital.</p

Health services in tuberculosis control: family focus and community orientation Servicios de salud para controlar la tuberculosis: enfoque en la familia y orientación para la comunidad Serviços de saúde no controle da tuberculose: enfoque na família e orientação para a comunidade

This study aimed to assess, according to patients' perception, the performance of the Health Services responsible for tuberculosis (TB) control, concerning the dimensions family focus and community orientation. A cross-sectional evaluative research was carried out with 108 TB patients. A questionnaire developed by Starfield and Macinko was used, adapted for TB care by Villa and Ruffino-Netto. Results evidence, in the first dimension, that health professionals (HP) are concerned with patients' signs and symptoms; and, at a lower level, with other health problems of relatives, endangering the comprehensive healthcare. In the second dimension, HP show little concern with the active search of cases, deficiency in HP training, and low rates of examined contacts. Results show the need to broaden HP's epidemiological view, as their attention is focused on patients, with few preventive actions concerning family/community. This evidences the need for a closer relationship among HP/patients/family/community.<br>Se evaluó, bajo la percepción de enfermos, el desempeño de Servicios de Salud responsables por controlar la tuberculosis (TB) en las dimensiones: enfoque en la familia y orientación para la comunidad. Como método, fue utilizada la investigación evaluativa transversal con 108 enfermos de TB. Se utilizó cuestionario de Starfield y Macinko, adaptado para atender la TB por Villa y Ruffino-Netto. Los resultados apuntan que, en la primera dimensión, los profesionales de la salud (PS) demuestran preocupación con señales/síntomas de pacientes y, en menor grado, con otros problemas de salud de familiares, comprometiendo el cuidado completo. En la segunda dimensión, los PS muestran poca preocupación con la búsqueda activa de casos, con la deficiencia de capacitación de PS, y con la baja tasa de contactos examinados. Se concluye que es necesario ampliar la visión epidemiológica de PS, cuya atención está focalizada en el enfermo, con pocas acciones preventivas sobre familia/comunidad, lo que muestra que es imprescindible una mayor aproximación entre PS/enfermos/familiares/comunidad.<br>O objetivo deste estudo foi avaliar, na percepção dos doentes, o desempenho dos Serviços de Saúde responsáveis pelo controle da tuberculose (TB) em relação às dimensões enfoque na família e orientação para a comunidade. Como método, foi usada a pesquisa avaliativa transversal com 108 doentes de TB. Utilizou-se questionário elaborado por Starfield e Macinko, adaptado para a atenção à TB por Villa e Ruffino-Netto. Os resultados apontam que, na primeira dimensão, os profissionais de saúde (PS) demonstram preocupação em relação aos sinais/sintomas dos pacientes e, em menor grau, sobre outros problemas de saúde dos familiares, comprometendo a integralidade do cuidado. Na segunda dimensão, os PS mostram pouca preocupação quanto à busca ativa dos casos, deficiência na capacitação de PS, baixa taxa de contatos examinados. Conclui-se pela necessidade de ampliar a visão epidemiológica dos PS, cuja atenção está focalizada no doente, com poucas ações preventivas sobre a família/comunidade, o que evidencia ser imprescindível maior aproximação entre PS/doentes/familiares/comunidade