[Current status of multidrug-resistant tuberculosis in Japan: a literature review and meta-analysis]

A literature review and meta-analysis of the incidence, clinical characteristics, and treatment outcomes associated with multidrug-resistant (MDR) tuberculosis (TB) in Japan was performed. An estimated 110-120 new cases of MDR-TB occur every year, constituting 0.7-0.8% of all cases starting TB chemotherapy in Japan. The frequency of MDR is higher in previously treated TB patients than in primary treatment patients; it is also higher among younger patients. Treatment outcomes are poor; the cure rate as conventionally defined is 50-60%. These primary characteristics of MDR-TB in Japan are similar to those reported abroad, although it appears that the Japanese MDR strains are more resistant, such as having a high frequency of extremely drug-resistant (XDR) strains, and a higher frequency of resistance to fluoroquinolones. However, we should remember that variations among institutions and the different methodologies used in reported studies are too numerous to allow any rigorous conclusions to be drawn. This will be a major challenge to the promotion of clinical studies and the control of MDR-TB in Japan.