ORIGINAL ARTICLE

Diagnostic accuracy of chest radiography in detecting mediastinal lymphadenopathy in suspected pulmonary tuberculosis

G H Swingler¹, G du Toit¹, S Andronikou², L van der Merwe³, H J Zar¹

¹ Division of Paediatric Medicine, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa
² Division of Paediatric Radiology, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa
³ Biostatistics Unit, Medical Research Council of South Africa, Cape Town, South Africa

Correspondence to:
Correspondence to:
Dr George Swingler
School of Child and Adolescent Health, University of Cape Town, Red Cross Children’s Hospital, Klipfontein Road, Rondebosch, 7700 South Africa; swingler{at}ich.uct.ac.za

Objective: To estimate the diagnostic accuracy of chest radiography in the detection of chest lymphadenopathy in children with clinically suspected pulmonary tuberculosis.

Methods: Design: Prospective cross sectional study. Setting: A short stay ward in a children’s hospital in South Africa. Patients: Consecutive children under 14 years of age admitted with suspected pulmonary tuberculosis. Diagnostic test: Antero-posterior and/or lateral chest x rays interpreted independently and blind to the reference standard by three primary care clinicians and three paediatricians, all with a special interest in tuberculosis. Reference standard: Spiral chest computed tomography (CT) with contrast injection.

Results: One hundred children (median age 21.5 months) were enrolled. Lymphadenopathy was present in 46 of 100 reference CT scans and judged to be present in 47.1% of x ray assessments. Overall sensitivity was 67% and specificity 59%. Primary care clinicians were more sensitive (71.5% v 63.3%, p = 0.047) and less specific (49.8% v 68.9%, p<0.001) than paediatricians. Overall accuracy was higher for the paediatricians (diagnostic odds ratio 3.83 v 2.49, p = 0.008). The addition of a lateral to an antero-posterior view did not significantly increase accuracy (diagnostic odds ratio 3.09 v 3.73, p = 0.16). Chance adjusted inter-observer agreement () varied widely between viewer pairs, but was around 30%.

Conclusions: Detection of mediastinal lymphadenopathy on chest x ray to diagnose pulmonary tuberculosis in children must be interpreted with caution. Diagnostic accuracy might be improved by refining radiological criteria for lymphadenopathy.

Abbreviations: AP, antero-posterior; CT, computed tomography

Keywords: lymph nodes; observer variation; radiography; sensitivity and specificity; thoracic; tuberculosis

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