Chest X-ray vs. Xpert® MTB/RIF assay for the diagnosis of sputum smear-negative tuberculosis in Uganda

SETTING: An out-patient clinic in a country with high rates of tuberculosis-human immunodeficiency virus (TB-HIV) co-infection. DESIGN: Cross-sectional analytical study of 123 adults with chronic cough and no previous anti-tuberculosis treatment. Demographic, clinical, chest X-ray (CXR) and GeneXpert (R) MTB/RIF data were collected. Proportions of TB diagnoses using both tests were calculated and compared using an unpaired t-test. RESULTS: Sixty-six patients (53.7%) were female and 35 (28.5%) tested positive for HIV; 21 (17.1%) were Xpert-positive, while 51 (42.5%) had CXR suggestive of TB (P = 0.0018), of whom only 15 (29.4%) were Xpert-positive. CXR was suggestive of pulmonary TB in 15 (71.4%) of the 21 patients with a positive Xpert test. CONCLUSIONS: The majority of the sputum smear-negative patients did not have TB on single Xpert testing. CXR gave an overestimate of sputum smear-negative TB cases.