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Evaluation of a tuberculosis diagnostic algorithm including XpertTB/RIF assay in a high HIV prevalence setting at district level

  • 2012/06/01
  • 2012/12/31
Chef de projet
  • Héléna Huerga
  • Kenya
  • Tuberculose
  • Médecins Sans Frontière

Diagnosis of tuberculosis remains a challenge in resource-limited countries. Sputum smear-microscopy is the only tuberculosis (TB) diagnostic test available in most of the peripheral health facilities. However, the sensitivity of this test is very limited, especially in HIV infected patients.  Mycobacterium tuberculosis (MTB) sputum culture is the gold standard for the diagnosis of tuberculosis but is rarely available in resource-limited settings. The 2007 World Health Organization revised diagnostic algorithm has been evaluated in Homa Bay, Kenya. In this study the clinical-radiological algorithm diagnosed 55% of the confirmed TB cases and only 30% of the patients started on TB treatment were confirmed TB cases.  Performing culture increased the proportion of confirmed TB cases started on treatment by 43%. Nevertheless, the use of culture did not reduce the risk of overtreatment.

The new Xpert MTB/RIF assay has shown good performance in HIV infected pulmonary TB (PTB) suspects with results available in 2 hours. Sensitivity in smear-negative patients ranges between 60% and 90%. Diagnostic algorithms including this technology may have a better impact to diagnose TB. However, to date there is no evaluation of diagnostic algorithms including the Xpert MTB/RIF assay in routine field conditions. Cost of the assay remains high and economic analyses are also necessary. The aim of this study is to evaluate a new diagnostic algorithm with Xpert MTB/RIF at district level in the Homa Bay District Hospital, a HIV prevalent setting.