Assessment of previous tuberculosis status using questionnaires, chest X-rays and computed tomography scans.

Abstract

Accurate diagnosis of previous pulmonary tuberculosis disease (PPTB) status is important clinically and in research. Reliable records of bacteriologically confirmed tuberculosis (TB) are frequently unavailable. To evaluate the use of questionnaires and chest imaging to determine PPTB status in a high TB prevalence population. PPTB status was assessed using two questionnaires, chest X-ray (CXR) and high-resolution chest computed tomography (CT) scans reported by experienced readers. The study population comprised adults aged >40 years diagnosed with obstructive lung disease in a community-based prevalence survey. The Burden of Obstructive Lung Disease (BOLD) questionnaire and a second comprehensive questionnaire (PTbQ) provided a history of PPTB in respectively 38% (n = 41) and 36.4% (n = 39) of 107 participants. On CXR, 43.3% (45/104) had evidence of PPTB, with good inter-reader agreement (κ = 0.73). Changes compatible with PPTB were identified on chest CT in 68.3% (71/104) of the subjects. Questionnaire and CXR had negative predictive values for PPTB of 48% and 47%, respectively, compared to a composite definition. Both questionnaire and CXR markedly underestimate the prevalence of previous TB in patients with chronic obstructive pulmonary disease. The combination of a structured questionnaire and CT scan is more useful when a diagnosis of PPTB needs to be ruled out.