Validating a scoring system for the diagnosis of smear-negative pulmonary tuberculosis in HIV-infected adults

PLoS One. 2014 Apr 22;9(4):e95828. doi: 10.1371/journal.pone.0095828. eCollection 2014.

Abstract

Background: The 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.

Methods: A 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.

Results: From 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).

Conclusion: The 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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adult
  • Female
  • HIV Infections / immunology*
  • Humans
  • Immunocompromised Host*
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Mycobacterium tuberculosis / growth & development
  • ROC Curve
  • Sputum / microbiology
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / immunology
  • Tuberculosis, Pulmonary / microbiology

Grants and funding

This study had the financial support of Ministério da Saúde do Brasil/Programa DST/AIDS/UNESCO (Projeto CSV 182/06) and of Ministério da Ciência e Tecnologia-CNPq/MS-SCTIE-DECIT (Processo n° 10567/2006-0). The authors were partially supported by CNPq (Scholarship 308311/2009-4 to R.A.A.X and Scholarship 301779/2009-0 para M.F.P.M.A and Scholarship 310911/2009-5 para H.R.L). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.