Tutorial CRP Blok RTS - 2Kelompok A13

EVALUATION OF REAL-TIME PCR OF PATIENT PLEURAL EFFUSION FOR DIAGNOSIS OF

TUBERCULOSISRosso F et al, 2011

BackgroundPleural tuberculosis diagnosis often requires invasive procedures such as pleural biopsy.

ObjectiveTo evaluate the role of real-time polymerase chain reaction (PCR) for the IS6110 sequence of M. tuberculosis in pleural fluid specimens as a rapid and non-invasive test for pleural TB diagnosis.

MethodCross-sectional study

Sample : 150 consecutive patients with pleural effusion. Overall, 98 patients had pleural TB and 52 had pleural effusion secondary to other disease.

CriteriaAge > 18 years old

Absence of known history or clinical or radiographic evidence of renal, cardiac or liver failure and no known diagnosis of cancer or TB at the moment of enrollment.

ResultsPCR TB NON-

TBSENS

SPEC PPV NPV

+ (n=45) 42 3 42.8 93.3

- (n=101) 52 49 94.2 48.5

Inhibited (n=4) 4 0

Total (n=150) 98 52

PCR test accuracy was calculated using the inhibition results only in the denominator.

ConclusionThe real-time PCR test of pleural fluid specimens is an useful and non-invasive additional assay for fast diagnosis of pleural TB.

Diagnosis WorksheetWas there an independent, blind comparison with a reference (“gold”) standard of diagnosis?

Yes. The absence of known history of clinical or radiographic evidence of renal, cardiac, or liver failure and no known diagnosis of cancer or TB at the moment of enrollment.

Was the diagnostic test evaluated in an appropriate spectrum of patients (like those whom it would be used in practice)?

Yes. Because all patients presenting with pleural effusion on chest radiography.

Was the reference standard applied regardless of the diagnostic test result?

Yes. Because there are negative controls and positive controls that were included for each sets of PCRs.

Was the test (cluster of tests) validated in a second, independent group of patients ?

Yes. In Brazil.

Are the results of this diagnostic study

important?

PCR Totals

Present Absent

C. Diagnosis of Cultures and HP

Positive 42 3 45

Negative 56 49 105

98 52 150

Sensitivity : 42,85%

Specificity : 94,23%

LR+ : 7,4

LR - : 0,6

PPV : 93,33%

NPV : 48,5%

Prevalence : 65,3%

Pretest Odds : 1,88

Post-test Odds : 13,912

Post-test probability : 93,3%

Post-test Prob – Pre-test Prob : 28%

Is the diagnostic test available, accurate and precise in your setting ?

No. Because pleural fluid specimens in 4 patients with positive culture for TB and demonstration of granuloma in pleural biopsy repeatedly demonstrated inhibition of the nucleic acid amplification.

Can you generate a clinically sensible estimate of your patient’s pre-test probability ?• Are the study patients similar to your own?• Is it unlikely that the disease possibilities or probabilities have changed since the evidence was gathered?

• Yes• No. It is likely to be changed since the difference between post-test probability and pre-test probability more than 20%

Will the resulting post-test probabilities affect your management and help your patient?• Could it move you across a test-treatment threshold?• Would your patient be a willing partner in carrying it out?

• Yes, because rapid diagnosis and initiation of chemotherapy are essential to prevent secondary fibrothorax and to avoid subsequent pulmonary or extrapulmonary TB development.• Yes, since it’s non-invasive and not really different with biopsy procedure.

Would the consequences of the test help your patient ?

Yes.

Thank you