MILIARY TUBERCULOSIS - DIAGNOSTIC-ACCURACY OF CHEST RADIOGRAPHY

Study objective: To assess the efficacy of the chest radiograph in ide ntifying patients with miliary tuberculosis. Design: Retrospective cas e-controlled review by three independent blinded chest radiologists. S etting: Provincial tuberculosis control center. Patients: Population-b ased sample, including all proved cases of miliary tuberculosis diagno sed in the Province of British Columbia, Canada, between November 1982 and November 1992. One hundred cases of miliary tuberculosis were ide ntified, of which 71 had chest radiographs available for review. Forty -four normal chest radiographs and 20 chest radiographs of patients wi th localized pulmonary tuberculosis were also included as controls. Ma in outcome measures: The primary outcome of measurements was the sensi tivity and interobserver variability of the chest radiograph in the di agnosis of miliary tuberculosis. The observers were also asked to desc ribe the pattern and extent of pulmonary abnormalities based on the In ternational Labor Organization (ILO) classification of pneunoconioses. Results: The three independent observers identified 42, 44, and 49 of the 71 cases of miliary tuberculosis, respectively (sensitivity, 59 t o 69%). The three observers incorrectly diagnosed miliary tuberculosis in 2, 0, and 2 of the 64 controls, respectively (specificity 97 to 10 0%), There was good interobserver agreement (90%, kappa=0.77). The nod ules measured less than 3 mm in diameter in 90% of cases fn which mili ary tuberculosis was correctly identified, In 10% of cases, the nodule s measured greater than 3 mm in diameter, The ILO profusion scores ran ged from mild (profusion score 1) in 45% of cases, through moderate (p rofusion score 2) in 27%, and severe (profusion score 3) in 28%. Concl usions: The chest radiograph allowed identification of 59 to 69% of ca ses of miliary tuberculosis with a high specificity and good interobse rver agreement.