Cartridge based Nucleic Acid Amplification Test : A game changer for diagnosis of pulmonary TB in HIV patients ?

Dr. Anupam Kumar Singh; Dibyajyoti Karmakar; Rajendra Kumar Jha

Volume : VIII, Issue : IV, April - 2019

Cartridge based Nucleic Acid Amplification Test : A game changer for diagnosis of pulmonary TB in HIV patients ?

Dr. Anupam Kumar Singh, Dibyajyoti Karmakar, Rajendra Kumar Jha

Abstract :

Background : World Health Organization (WHO) has recommended CBNAAT ( Cartridge Based Nucleic Acid Amplification test) as first line diagnostic modality for detection of pulmonary TB(Tuberculosis) in HIV patients due to increased case finding rate in HIV patients and rapid diagnosis of MDR–TB(Multi–Drug Resistant TB) Aim : Our Aim was to compare diagnostic accuracy of sputum microscopy with CBNAAT for detection of pulmonary Tuberculosis in HIV patients Material and Methods. We screened all patients present to HIV clinic for pulmonary TB.. We collected two sputum samples for microscopy using ZN stain , one sputum sample for CBNAAT and one sputum sample for BACTEC based culture in each patient . Using BACTEC culture positive as gold standard, we determined comparative sensitivity, specificity, Positive Predictive Value (PPV),Negative Predictive value(NPV), Positive Likelihood Ratio (PLR) and Negative Likelihood Ratio(NLR) of CBNAAT and sputum microscopy using SPSS 15.0 software . Results : 204 patients were included in study .71/204 (34.8 %) patients were sputum culture positive. Overall sensitivity, specificity, PLR, NLR,PPV,NPV of CBNAAT was [85.92(75.6 – 93.0), 97.74(93.5 – 99.5), 38.09, 0.14, 95.3 %, 92.9 %] and of smear microscopy was [ 39.44 (28.0 – 51.7), 96.99 (92.5 – 99)13.11, 0.62,75%,87.5% ] respectively .Ten out of 61 (16.39 %) CBNAAT positive patients were Rifampicin resistant. The Test accuracy as represented by AUROC ( Area under receiver operator characteristics) was significantly higher for CBNAAT compared to Sputum microscopy [ 0.91 versus 0.68 ,p<0.001). Conclusion : CBNAAT–TB is more accurate, rapidly performed ,valid and reliable alternative to sputum microscopy for detection of pulmonary tuberculosis in HIV patients.