Evaluation of XpertMTB/Rif performance for diagnosis of tuberculosis among HIV positive patients in northern Tanzania

Abstract

Background: Diagnosis of tuberculosis (TB) in patients co-infected with HIV poses an important challenge since they are usually smear negative for pulmonary TB. The reason for this is the low sensitivity and specificity of microscopy as the standard diagnostic method. This study aimed to evaluate the performance of the XpertMTB/Rif tool for TB diagnosis among TB-HIV co-infected patients in order to characterize TB features in HIV co-infections. The study assessed the sensitivity, specificity and positive and negative predictive values of XpertMTB/Rif for TB detection in symptomatic and asymptomatic patients.

Methods: This was a cross-sectional analytical study involving 69 patients as study participants. Demographic, clinical, laboratory and radiological data were collected. The performance of the XpertMTB/RIF and microscopy using LJ culture as a gold standard were determined and compared.

Results: XpertMTB/Rif had a higher sensitivity (100%), specificity (100%), PPV (79.2%) and NPV (98.9%) as compared to microscopy. There was a strong correlation between XpertMTB/Rif, LJ culture and Microscopy in terms of their sensitivity and specificity. 

Conclusion:  While using TB symptoms screening tool alone in HIV infected individuals may result into overtreatment, relying on microscopy alone has the potential of TB under-diagnosing, miss-diagnosing and delayed treatment. Our results show XpertMTB/Rif to be highly sensitive and specific to detect all culture positive TB cases among HIV patients. We recommend the adoption of XpertMTB/Rif as an early TB diagnosis tool among HIV patients for early detection of TB among HIV patients.