Emergence of multidrug-resistance in tuberculosis cases: Role of risk factors

Abstract

Background: In 2013, 6.1 million tuberculosis (TB) cases were reported to WHO. Of these, 5.7 million were people newly diagnosed and another 0.4 million were already on treatment. Globally, 3.5% of new and 20.5% of previously treated TB cases were estimated to have had multidrug resistant (MDR) - TB. The previous treatment for TB is the strongest risk factor for development of MDR-TB. The current scenario states that even treatment naive patients are also at risk. Methods & Materials: The study was a prospective observational study aimed to identify the group at high risk was carried out over a period of 9 months in govt. hospitals in the Telangana region. The patients were enrolled based on the MDR-TB suspect criteria: failure, S+ at 4th month (retreatment case), contact of known MDR-TB case, S+ at diagnosis (retreatment case), any follow up S+, S- at diagnosis (retreatment case), and HIV-TB case. Results were analyzed using fisher's exact test. Results: Among 2033 suspected MDR-TB patients, 453 (22%) showed resistance to isoniazid/rifampicin or isoniazid and rifampicin. Out of 453, 199 (43%) were resistant to Isoniazid, 173 (38%) were resistant to both Isoniazid and rifampicin, and 81 (17%) were resistant to rifampicin. Patients aging <45 years (76%) and >45 years (23%) were found to be at equal risk (p=0.085). Analyzing 453 MDR-TB cases, males (78%) were found to be at higher risk to develop MDR-TB (p=0.002). But if we consider the whole suspect population (2033), out of 1641 male suspected cases, 355 (21%) were diagnosed with MDR-TB and out of 392 female suspected cases, 98 (25%) were diagnosed with MDR-TB. This clearly states that both genders are at equal risk. Among 453 suspected cases, S+ at diagnosis-retreatment case (291) were found to be at high risk followed by any follow up S+ (84) and HIV TB case (32). Conclusion: The study concluded that each and every suspect individual is at equal risk to develop MDR-TB. The high level of significance in risk of developing MDR-TB directs this study further to check for the strategies to reduce the rate of TB and MDR.