Screening of tuberculous pleural effusion by discriminant analysis.
METHODS
Pneumology Department of a 635-bed acute-care teaching hospital in Valencia, Spain.


OBJECTIVE
To assess the value of discriminant analysis as a method of optimizing the discriminant power of routine radiographic features and a panel of laboratory parameters including biochemical analyses of pleural fluid for differentiation between tuberculous and non-tuberculous pleural effusion.


METHODS
A series of 47 variables were retrospectively obtained from the medical records of 189 patients with exudative pleural effusion (tuberculous pleurisy, n = 78; non-tuberculous pleurisy, n = 111). A backward elimination method was applied until the best discriminant function was found.


RESULTS
The most powerful predictor of tuberculous pleural effusion was a function that consisted of four variables, as follows: age (years); tuberculin skin test (mm of induration at 48 hours); white blood cell count (cells/mm3); and bloodstained exudate (coded as yes = 1, no = 2). This function showed a sensitivity of 90%, specificity of 87%, positive predictive value of 83%, negative predictive value of 92%, and was able to give an 88% rate of correct classification.


CONCLUSIONS
The calculated discriminant function based on the patient's age, peripheral leukocyte count, tuberculin skin test and blood in the exudate is a simple, rapid and inexpensive method for screening tuberculous etiology in patients with pleural effusion.
Carrion-Valero
F
F
Service of Pneumology, Hospital Clinico Universitario, Valencia, Spain.
Perpiñá-Tordera
M
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D016002:Discriminant Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000378:metabolism / Q000382:microbiology*; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014396:Tuberculosis, Pleural / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism