The background of drug-resistant tuberculosis patients on the basis of the annual report database for 2007-2009 in Japan]

In this study, the background of drug-resistant tuberculosis (TB) patients in Japan was analyzed using the annual report database for 2007-2009. The results of the drug susceptibility test of 15,425 patients who were diagnosed with pulmonary TB between 2007 and 2009 were obtained and analyzed. The chi-square test for independence between susceptibility test results and parameters (i.e., sex, age, nationality, etc.) was conducted. Logistic regression analysis was performed using the variables (20s, 30s, 40s ..., new treatment, retreatment, etc.) of parameters that were statistically significant by chi-square test. The risk of multi-drug resistance (MDR) among TB patients who underwent retreatment was significantly high (odds ratio = 11.3, 95% CI: 7.7-16.6, p < 0.001, reference = new treatment), and the risk of MDR among foreigners who had entered Japan within the last 5 years was also high (odds ratio = 9.5, 95% CI: 4.6-19.4, p < 0.001, reference = Japanese). Moreover, logistic regression analysis was performed for TB patients who had previously undergone treatment. The risk of MDR was higher among the patients treated after 1970 than those treated before 1970. Especially, the risk of MDR among the patients previously treated in 1990-1999 was extremely high (odds ratio = 20.8, 95% CI: 5.7-75.0, p < 0.001, reference = before 1970). The risk of MDR among previously treated foreigners who had entered Japan within the last 5 years was also high (odds ratio = 3.8, 95% CI: 1.1-13.2, p = 0.036). Similar to the results for MDR, the risk of resistance to one or more drugs was significantly high among TB patients who underwent retreatment for TB (odds ratio = 2.2, 95% CI: 1.9-2.6, p < 0.001) and foreigners who had entered Japan within the last 5 years (odds ratio = 1.8, 95% CI: 1.3-2.5, p < 0.001); however, their risk of resistance to one or more drugs was lower than that for MDR. In addition, the odds ratios of age groups younger than 80 years to those over 80 years were obtained. They were 2.1 (95% CI: 1.5-2.9) in 0-29 years, 2.2 (95% CI: 1.6-3.0) in 30-39 years, 2.2 (95% CI: 1.7-3.0) in 40-49 years, 2.1 (95% CI: 1.6-2.8) in 50-59 years, 1.9 (95% CI: 1.4-2.5) in 60-69 years, and 1.5 (95% CI: 1.2-1.8) in 70-79 years. With respect to the background of high MDR among TB patients who underwent retreatment and foreigners who have recently entered Japan, the usage of RFP and poor adherence to drugs and entry from high-prevalence countries with high MDR risk were suspected. Regarding the background of generational differences in resistance to one or more drugs, it was suspected that most people over 80 years of age had been infected with TB bacilli in the distant past, before anti-TB drugs were available, when drug-resistant bacilli had not yet emerged. However, the younger generations have become more susceptible to drug-resistant TB bacilli because anti-TB drugs were being widely used when they were born, and drug-resistant bacilli were prevalent in the world.