Sonography to rule out tuberculosis in Sub-Saharan Africa: A prospective observational study

Abstract

Background. Patients with suspected tuberculosis are often overtreated with antituberculosis drugs. We evaluated the diagnostic value of the focused assessment with sonography for HIV-associated tuberculosis (FASH) in rural Tanzania. Methods. In a prospective cohort study, the frequency of FASH signs was compared between patients with confirmed tuberculosis and those without tuberculosis. Clinical and laboratory examination, chest x-ray, Xpert MTB/RIF assay, and culture from sputum, sterile body fluids, lymph node aspirates, and Xpert MTB/RIF urine assay was done. Results. Of 191 analyzed patients with a 6-month follow-up, 52.4% tested positive for human immunodeficiency virus, 21.5% had clinically suspected pulmonary tuberculosis, 3.7% had extrapulmonary tuberculosis, and 74.9% had extrapulmonary and pulmonary tuberculosis. Tuberculosis was microbiologically confirmed in 57.6%, probable in 13.1%, and excluded in 29.3%. Ten of eleven patients with splenic or hepatic hypoechogenic lesions had confirmed tuberculosis. In a univariate model, abdominal lymphadenopathy was significantly associated with confirmed tuberculosis. Pleural- and pericardial effusion, ascites, and thickened ileum wall lacked significant association. In a multiple regression model, abnormal chest x-ray (odds ratio [OR] = 6.19; 95% confidence interval [CI], 1.96-19.6; P < .002), ≥1 FASH-sign (OR = 3.33; 95% CI, 1.21-9.12; P = .019), and body temperature (OR = 2.48; 95% CI, 1.52-5.03; P = .001 per °C increase) remained associated with tuberculosis. A combination of ≥1 FASH sign, abnormal chest x-ray, and temperature ≥37.5°C had 99.1% sensitivity (95% CI, 94.9-99.9), 35.2% specificity (95% CI, 22.7-49.4), and a positive and negative predictive value of 75.2% (95% CI, 71.3-78.7) and 95.0% (95% CI, 72.3-99.3). Conclusions. The absence of FASH signs combined with a normal chest x-ray and body temperature <37.5°C might exclude tuberculosis.