Diagnostic accuracy of chest radiography in detecting mediastinal lymphadenopathy in suspected pulmonary tuberculosis
- 1Division of Paediatric Medicine, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa
- 2Division of Paediatric Radiology, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa
- 3Biostatistics Unit, Medical Research Council of South Africa, Cape Town, South Africa
- 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;
- Accepted 20 February 2005
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 (κ) 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.
The Medical Research Council (South Africa) and the University of Cape Town funded this study but played no role in study design, the collection, analysis or interpretation of data, the writing of the report, or the decision to submit the paper
Competing interests: none declared
Ethical approval: written informed consent for chest radiography and CT was obtained from the parent or legal guardian. The study was approved by the Research Ethics Committee of the University of Cape Town (Ref No: 258/2000)