Comparative analysis of cartridge-based nucleic acid amplification test (CBNAAT) with conventional methods in the diagnosis of pediatric tuberculosis at a tertiary care center.

BACKGROUND: Tuberculosis is an important cause of morbidity and mortality among children. Early diagnosis and treatment in children are challenging, more so in resource-limited, tuberculosis-endemic countries. In 2017, the WHO endorsed the use of CBNAAT for tuberculosis diagnosis. We have undertaken this study to evaluate the diagnostic value of CBNAAT in pediatric tuberculosis in comparison to other methods like microscopic detection of acid-fast bacilli and detection of mycobacteria-by-mycobacteria growth indicator tube (MGIT).

MATERIAL AND METHODS: This hospital-based, cross-sectional, observational prospective study was conducted in the department of pediatrics, at a tertiary care center. A detailed history, general physical examination, and relevant physical examination were performed systematically and the findings were noted in the proforma. All necessary basic investigations like CBC, ESR, X-Ray, etc., and advanced investigations like MRI, CT, and FNAC were done as per the requirement of the subjects and the results were mentioned in the study proforma. Sensitivity, specificity, positive and negative predictive value, and diagnostic accuracy were calculated for various methods. A comparison between the two methods was done using the Mc Nemar test. p-value ≤0.05 was taken as statistically significant. All statistical analyses were done using Epi info version 7.2.1.0 statistical software.

RESULTS: Among 102 children suspected to be suffering from tuberculosis, the maximum number of TB cases were found in the age group of 11-16 years (43.2%), there were 58.2% of females, 58.8% belonged to the rural population, fever (78.4%) was the most common presenting symptom and 35.3% had a history of contact. In the present study, CBNAAT and ZN staining had equal sensitivity (60.8%) and specificity (100%) while the yield for MGIT culture was quite low (sensitivity 37.3%, specificity 100%).

CONCLUSIONS: CBNAAT as a test was found to be useful, especially for early diagnosis and detection of rifampicin resistance in pediatric tuberculosis against MGIT culture. Since MGIT results become available only after 42 days and have a relatively lower yield so they can be utilized only in a selected clinical situation or in patients with high suspicion of tuberculosis where another test is not able to detect the organisms.