Abstract
BackgroundThe challenge of diagnosing smear-negative pulmonary TB (tuberculosis) in people living with HIV justifies the use of instruments other than the smear test for diagnosing the disease. Considering the clinical-radiological similarities of TB amongst HIV-infected adults and children, the proposal of this study was to assess the accuracy of a scoring system used to diagnose smear-negative pulmonary TB in children and adolescents, in HIV-infected adults suspected of having smear-negative pulmonary TB.MethodsA Phase III validation study aiming to assess the diagnostic accuracy of a scoring system for diagnosing smear-negative pulmonary TB in HIV-infected adults. The study assessed sensitivity, specificity, positive and negative likelihood ratios, and positive and negative predictive values of the scoring system. Three versions of the scoring system were tested.ResultsFrom a cohort of 2,382 (HIV-infected adults), 1276 were investigated and 128 were diagnosed with pulmonary TB. Variables associated with the diagnosis of TB were: coughing, weight loss, fever, malnutrition, chest X-ray, and positive tuberculin test. The best diagnostic performance occurred with the scoring system with new scores, with sensitivity = 81.2% (95%-CI 74.5% –88%), specificity = 78% (75.6% –80.4%), PPV = 29.2% (24.5% –33.9%) and NPV = 97.4% (96.4% –98.4%), LR+ = 3.7 (3.4–4.0) and LR− = 0.24 (0.2–0.4).ConclusionThe proposed scoring system (with new scores) presented a good capacity for discriminating patients who did not have pulmonary TB, in the studied population. Further studies are necessary in order to validate it, thus permitting the assessment of its use in diagnosing smear-negative pulmonary TB in HIV-infected adults.
Highlights
Tuberculosis (TB) is the most frequent cause of death in people living with HIV (PLHIV) [1], with high mortality in smearnegative cases [2]
From a cohort of 2,382 HIV-infected adults, 1383 were pulmonary TB suspects in accordance with the criteria defined in the present study
The performance of the adults with suspected smear-negative pulmonary TB (ASS) in the study population fell below that of the Brazilian Ministry of Health scoring system with the population for which it was originally purposed. Studies that used this score system for diagnosing TB in children and adolescents reported sensitivity of 89% to 92% and specificity of 70% to 86% with 30 points [19,14], in agreement with the results initially described when assessing the accuracy of the test [30]
Summary
Tuberculosis (TB) is the most frequent cause of death in people living with HIV (PLHIV) [1], with high mortality in smearnegative cases [2]. Diagnosis of smear-negative pulmonary TB in this group, if specific treatment is initiated quickly, has a favorable impact on mortality [3,4]. Sputum smear microscopy (SSM) is the main method used for diagnosing pulmonary TB, especially in countries with limited financial resources [6,7] it fails to detect up to 50% of TB cases in PLHIV [5]. While this method achieves high specificity, sensitivity is not high, especially in the diagnosis of paucibacillary or extra-pulmonary forms of the disease [8]. Considering the clinical-radiological similarities of TB amongst HIV-infected adults and children, the proposal of this study was to assess the accuracy of a scoring system used to diagnose smear-negative pulmonary TB in children and adolescents, in HIV-infected adults suspected of having smearnegative pulmonary TB
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