Risk factors for multidrug resistance among previously treated patients with tuberculosis in eastern China: a case–control study

Abstract

Previous treatment has been documented as a major risk factor for multidrug-resistant tuberculosis (MDR-TB). However, risk factors for MDR-TB among previously treated patients in China are unclear. This study aimed to ascertain the risk factors for MDR-TB in this particular population in China. A case-control study was conducted from July through August 2011 in five cities of Zhejiang Province. Cases were previously treated TB patients who had disease resistant to at least isoniazid and rifampin, whereas controls were previously treated TB patients who had disease sensitive to isoniazid and rifampin. Ninety-eight cases and 83 controls were identified. Multivariate analysis showed that a duration of first treatment of more than 8 months (odds ratio (OR) 2.18, 95% confidence interval (CI) 1.05-4.52), more than three prior episodes of anti-TB treatment (more than 2 months of continuous treatment as one episode) (OR 5.57, 95% CI 2.38-13.00), adverse effects of anti-TB medication (OR 3.63, 95% CI 1.79-7.36), and more than three TB foci in the lung (OR 2.17, 95% CI 1.08-4.37) were associated with MDR-TB in previously treated TB patients. Low family income (p=0.056) was marginally significant in the univariate analysis. Particular clinical diagnostic results, such as more than three TB foci in the lung, non-standard or irregular therapy, and adverse effects of anti-TB medication, were found to be associated with MDR-TB in previously treated TB patients. High quality directly observed treatment should be strengthened to ensure that the previously treated patients can receive standard and regular regimens.