08 Arijitd Medicine Discussion

DISCUSSION

i

n the evaluation of a pleural effusion the first step is to differentiate the transudates & exudates. It bears its implication in arriving at an etiological

diagnosis as the diagnostic and the therapeutic strategies for the transudates and exudates are different. An exudative effusion requires extensive sometimes invasive procedures for its etiological diagnosis, on the other hand a transudative pleural effusion requires treatment directed only towards the primary disease process. Histopathological examinations are confirmatory, but it has its limitations ions as the specimen yield is very low, sometimes up to 30% [Escudero et al 1990] and being an invasive technique it has its hazards.The laboratory parameters such as Light’s criteria [Light et al 1972], pleural fluid protein value has variable results in the differential diagnosis as reported by many workers. Keeping all these factors in mind the present study was undertaken to study the significance of serum–effusion albumin gradient in differential diagnosis of pleural effusion and compare with the already established Light’s criteria. The present study comprised of 40 cases of pleural effusion in which the etiology was established by clinical examination, Radiological investigations,

pleural

fluid

cytology,

special

laboratory

methods

and

histopathological examination of pleural biopsy specimen in selected cases. In the present series 75% were male and 25% cases were females belonged to age group of 13–83 years. Among 40 cases of transudates and exudates, 50% had right sided pleural effusion, 30% had left sided and 20% had bilateral pleural effusions. Differential Diagnosis of Transudates and Exudates: Classically pleural effusion are divided into transudates and exudates. In the present study of 40 cases of pleural effusion 65% were established as exudates and 35% as transudates.

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Pleural Fluid Proteins in Differential Diagnosis of Pleural Effusion: In the present study of 40 cases of pleural 55% of exudates & 45% of transudates were differentiated by a pleural fluid protein value of 3 g/dl. The sensitivity and specificity of these parameters is 80% & 70% respectively. Total misclassification of 25% occurred with this parameter ie 23.07% misclassified exudates and 28.52% of treansudates. In a study, Carr & Power [1958] showed that a pleural fluid protein value of 3 g/dl could differentiate 64% of exudates & 50% of transudates with total misclassification of 21%. In a study by K.B. Gupta et al showed that pleural fluid protein value of 3 g/dl misclassified 25% of exudates and 18.7% of transudate with sensitivity and specificity of 83.3% and 75% with total misclassification of 20%. Pleural Fluid to Serum Protein in Differential Diagnosis of Pleural Effusion: In the present study of 40 cases of pleural effusion pleural fluid to serum protein ratio of.5 separated 57.5% as exudates & 42.5% as transudates with sensitivity and specificity of 85% & 73.7% with total misclassification rate of 20%. This parameter correctly classified 81% of exudates and 85% of transudates. Misclassification rate for transudates 21.42% and for exudates is 1.9%. Light et al [1972]; in their study reported that a pleural fluid to serum protein ratio of >0.5 correctly classified 92% of transudates & 90% of exudates. Valdes et al [1991] also found in their study that this parameter correctly classified 89% of transudates and 84% of exudates.

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Ram et al [1995] also reported that the pleural fluid protein to serum protein ratio of 0.5 correctly classified 81.5% of transudates and all exudates with a misclassification rate of 15%. K.B. et al found a sensitivity and specificity of 85% and 66.6% with this parameter and are total misclassification of 18%. From the above results by the above results by the other workers it is found that results obtained in the present study are comparable. The misclassification rate is higher in the present study.

Pleural Fluid Protein and Pleural Fluid to Serum Protein Ratio in Differential Diagnosis of Pleural Effusion: In the present study of 40 cases of pleural effusion pleural fluid protein of 3 g/dl and p/s of.5 separated 55% as exudates and 45% as transudates with true classification rate of 82% as exudates and 83.3% as transudates. Total misclassification rate of 17.5% occurred.

Pleural Fluid LDH in Differential Diagnosis of Pleural Effusion: In the present study of 40 cases of pleural effusion pleural fluid LDH of 200 U/L separated 60% as exudates and 40% as transudate. True classification was 87% for exudates and 82% for transudates. Total misclassification of 17.5% occurred. The sensitivity and specificity of this parameter is 86% & 77%. K.B. Gupta et al found a sensitivity and specificity of 80% & 75% with this parameter with total misclassification of 21.6% occurred. From the above results by other workers it is found that results found in the present study are comparable. The misclassification rate in the present study is 17.5% ie low compared to the above study.

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Pleural Fluid LDH to Serum LDH of 0.6 in Differential Diagnosis of Pleural Effusion: In the present study of 40 cases of pleural effusion pleural fluid LDH to serum LDh of.6 separated 67.5% as exudates and 32.5% as transudates with true classification of 88.8% as exudates & 84.6% as transudates. The sensitivity & specificity of this parameter is 92% & 73.3% with total misclassification of 12.5%. Light et al found a total misclassification of 10% with this parameter. K.B. Gupta et al found a total misclassification of 15.4% with this parameter. From the results found by other workers they are quite similar but the misclassification rate in the present study is 12.5%. Pleural Fluid LDH of 200 U/L & P/S LDH of.6 in Differential Diagnosis of Pleural Effusion: In the present study of 40 cases of pleural effusion pleural fluid LDH of 200U/L & P/S LDH of.6 separated 70% as exudates & 30% as transudates with true classification of 93% for exudates & 88% for transudates with total misclassification of 10%. The sensitivity & specificity of this parameter is 90.4% & 82.6%. Serum–Effusion Albumin Gradient of 1.2g/dl in Differential Diagnosis of Pleural Effusion: In the present study of 40 cases of pleural effusion serum effusion albumin gradient of 1.2g/dl separated 65% as exudates & 35% as transudates with true classification rate of 96.15% for exudates & 94% for treansudates with total misclassification of only 5%. The sensitivity and specificity of this parameter is 96.1% & 93%.

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Roth et al in a series of 59 patients used serum effusion albumin gradient of 1.2g/dl & classified all the transudates correctly & only 2 exudates were miss classified with total misclassification rate of 3.3%. The sensitivity & the specificity of the parameter used was 90% & 92%. E Razi et al attained a sensitivity & specificity of 91.5% & 92.86% respectively. K.B. Gupta et al attained a sensitivity & specificity of 97.9% & 100% with total misclassification rate of 2%. M.C. Dhar et al obtained a sensitivity & specificity of 100% & 94% with this parameter. From the results obtained by the above workers, they are quite similar to the present study. Misclassification rate obtained in the present study is 5%. Comparative Analysis of the Parameters Used In the Study of 40 Cases of Pleural Effusion:

PARAMETER

EXUDATE CLASSIFIED CORRECTLY [%]

TRANSUDATES CLASSIFIED CORRECTLY [%]

MIS– CLASSIFICATION RATE [%]

PF Protein [3gm/dl]

72.70

77.70

25.00

P/S Protein [0.5]

78.26

82.35

20.00

PF Protein + P/S Protein

81.80

83.30

17.50

PF LDH [2001U/L]

83.30

81.25

17.50

P/S LDH [0.6]

88.80

84.60

12.50

PF LDH + P/S LDH

92.80

83.30

10.00

SEAG of 1.2 gm/dl

96.15

93.60

5.00

The parameters of protein, LDH & Serum–Effusion Albumin gradient were studied in the 40 cases of pleural effusion & compared with the established diagnosis of pleural effusion in the present study. The study

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revealed that even though the parameter of pleural fluid protein of 3 gm/dl, pleural fluid to serum protein ratio of.5, pleural fluid LDH level of 200 U/L & pleural fluid LDH to Serum LDH ratio of.6 are useful in differentiating the exudates & transudates. The greater differential value is found with the SEAG value of 1.2 gm/dl which correctly classified 96.15% of exudates & 93.6% of transudates with a total misclassification of only 5% & with a sensitivity & specificity of 96.1% & 93%. Therefore the present study shows that Serum–Effusion Albumin gradient of 1.2 gm/dl is a useful parameter in differential diagnosis of pleural effusion which can be tried as a first step in the evaluation of cases of pleural effusion. The graphical representation of the misclassification rate of various parameters showed in the above table is given in Fig–13.

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