Wednesday September 24, 2008
Is there any change in criteria for identifying exudative pleural effusion

Heffner and Steven Sahn did the study to determine multilevel likelihood ratios for pleural fluid tests that are commonly used to discriminate between exudative and transudative pleural effusions. Studies were identified by searching MEDLINE and related bibliographies. Data were obtained for 1,448 patients from seven primary investigators led to modified Light criteria. These incorporate the test combination of the value of LDH of pleural fluid to serum ratio, PF/serum protein ratio, PF/serum LDH ratio, LDH of pleural fluid alone. If any of these being positive that indicates exudative effusion.


Pleural fluid Test/ Metaanalysis cut Points
Pleural fluid protein = more than 2.9 g/dl
PF/serum protein ratio = more than .5
Pleural fluid LDH = more than 0.45 upper limit of normal
PF/serum LDH ratio = more than 0.6
Pleural fluid cholesterol = more than 45 mg/dl


Conclusion: Multilevel likelihood ratios combined with a clinician’s estimation of the pretest probability of an exudative effusion improve the diagnostic accuracy of discriminating between exudative and transudative pleural effusions. Likelihood ratios avoid the use of confusing terms, such as “pseudoexudates,” that derive from the use of single cutoff points for pleural fluid tests.



Reference: click to get abstract

Heffner JE, Sahn SA, Brown LK. Multilevel Likelihood Ratios for Identifying Exudative Pleural Effusions. CHEST 2002; 121:1916–1920