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COMPARATIVE ACCURACY OF CARTRIDGE BASED NUCLEIC ACID AMPLIFICATION TEST AND SPUTUM MICROSCOPY FOR DIAGNOSIS OF PULMONARY TUBERCULOSIS IN HIV POSITIVE PATIENTS.

TB- HIV CO-INFECTION

Prevalence of pulmonary TB in HIV positive patients in India

10-15 percent in patients without respiratory symptoms

20-30 percent in patients with respiratory symptoms (1)

HIV patient has 50 % lifetime risk of developing tuberculosis as compared to 10 percent in HIV negative person in India (1)

1. The situation of HIV/M.Tuberculosis Co-infection in India. P.Seth.The open Infectious Disease Journal .2011;5:51-59

Performance of Sputum Microscopy in HIV patients

• Poor sensitivity (35%-50 %) of sputum microscopy in HIV patients due to lesser number of cavities. (1)

• Need for alternative measures :

Rule based tests

NAAT

Culture

1. Diagnosis and treatment of TB in HIV patients. C.Padmapriyadrshini et al. IJMR.201;130:850-65

Detection of pulmonary tuberculosis in HIV patients

• WHO : CBNAAT• RNTCP : Sputum Microscopy

Performance of CBNAAT in HIV patients

CBNAAT : Real-time PCR assay , cartridge based ,no processing needed, sensitive as well as specific

Evidence for CBNAAT in HIV patients

Aims and objectives

To find out comparative accuracy of CBNAAT and sputum microscopy in HIV positive patients

To find out prevalence of Rifampicin Ressistance in HIV positive patients

Meta-analysis of CBNAAT in HIV patients incorporating our data and new studies missed by cochrane review.

Methodology

. We assessed HIV positive adults referred to with pulmonary symptoms suggestive of tuberculosis

. two sputum samples for microscopy using ZN stain ,one sputum sample for CBNAAT and one sputum sample for BACTEC based culture in each patient

Methodology

. Using BACTEC culture positive as gold standard, we determined comparative sensitivity, specificity,Positive Predictive Value, Negative Predictive value, Positive Likelihood Ratio and Negative Likelihood Ratio of CBNAAT and sputum microscopy using SPSS 15.0 software .

. We also did a meta-analysis combining various studies across the world with our study to determine pooled test performance of CBNAAT using MetaDisc 1.4 software.

Results :Sputum microscopy

. Out of 100 screened patients ,90 included with adequate sputum volume, 33 were culture positive and 57 were culture negative

Results :sputum microscopy

Results :CBNAAT

Results :CBNAAT

• CBNAAT picked up 14 extra cases missed by Sputum microscopy. 2/29 patients were Rifampicin ressistant

Comparative Accuracy :ROC curves

Comparative Accuracy :ROC curves

Meta-analysis of Evidence

Meta-analysis of Evidence

Meta-analysis of Evidence

Conclusion

• CBNAAT performs better than sputum microscopy in diagnosis of pulmonary tuberculosis in HIV patient

• CBNAAT can tell about Rifampicin Ressistance Quickly• CBNAAT has proved superior to sputum microscopy in

cochrane review and meta-analysis done by us• CBNAAT is recommended as first line modality for diagnosis of

tuberculosis in HIV patients and re-treatment cases.• CBNAAT is an add-on in diagnosis of pulmonary tb in HIV

negative smear negative cases with suspicion of kochs chest

Case : Utility of negative CBNAAT

• A 40 year old HIV positive male presents with cough for two weeks , sputum AFB – 1+, CBNAAT negative

Case : Utility of negative CBNAAT

Case : Utility of negative CBNAAT

• Diagnosis : Atypical Mycobacterial infection.