Diagnostic value of the commercial MycoDotTM test in the diagnosis of active pulmonary tuberculosis in Nepalese population

Background: A rapid, technically non-demanding and inexpensive diagnostic test is needed to improve the early detection and better management of active pulmonary tuberculosis especially in resource limited areas. Objective: To assess the diagnostic value and usefulness of the commercially available MycoDot TM (DynaGen Inc., Cambridge, MA, USA) in the diagnosis of active pulmonary tuberculosis in Nepalese population. Materials and Methods: A prospective study was done from January 2008 to August 2008 on a group of 120 sputum smear positive adult patient group aged 17 to 78 years, confirmed cases of active pulmonary tuberculosis (with TB) were enrolled and sera samples collected from them. The second group comprised of 105 healthy controls with no history of pulmonary tuberculosis (without TB) and sera samples collected from them. The MycoDot TM serologic test was done on the sera samples collected from both the study groups according to the manufacturer's instructions. Results: Of the sera collected from 120 sputum smear positive cases (with TB group), 48 sera specimens were MycoDot TM test positive (sensitivity = 40%; 95% CI 31.68-48.94). Healthy controls (without-TB group) - 8 sera samples were found to be positive by the MycoDot TM test and the remaining 97 sera samples tested negative by this serologic test (specificity = 92.38%; 95% CI 85.68-96.09). The value for % false positive was 7.61% and for % false negative was 60%. The positive predictive value and the negative predictive value was 85.71% (95% CI 73.22-93.20) and 57.4% (95% CI 49.56-64.88), respectively. Conclusion: The MycoDot TM test with its rapidity (completed within 20 min), easy - to - perform format and no expensive instrumentation required - had high specificity but a relatively low sensitivity in the study group subjects and thus could be used only as an additional test in the diagnosis of active pulmonary tuberculosis and to be interpreted judiciously along with clinical findings.