Trends in the Nontuberculous Mycobacterial Disease Mortality Rate in Japan: A Nationwide Observational Study, 1997-2016

Background. The incidence of nontuberculous mycobacterial (NTM) infections has been increasing worldwide, becoming a significant healthcare burden especially among elderly people. This study aimed to evaluate the trends in NTM-associated mortality in Japan. Methods. This study used vital statistics data and data on all NTM-associated deaths (N = 18 814) among individuals aged >= 40 years in Japan from 1997 to 2016. We calculated the crude and age-adjusted mortality rates by age and sex and used joinpoint regression to analyze trends and estimate the average annual percentage change (AAPC). We compared crude NTM- and tuberculosis-associated mortality rates by sex. Results. The overall crude annual mortality rate increased from 0.63/100 000/year in 1997 to 1.93/100 000/year in 2016 and was the highest among individuals aged 80-84 years. The AAPC of the crude mortality rates among men of all ages and women aged 40-59 years were stable but increased among women aged 60-79 years (3.5%; 95% confidence interval [CI ], 2.8-4.3) and >= 80 years (4.3%; 95% CI, 3.7-4.9). Among men, the age-adjusted mortality rates did not show a significant trend, while among women, the rates increased over the study period (AAPC, 4.6%; 95% CI, 2.7-6.6). In women, the crude NTM-associated mortality rate exceeded the tuberculosis mortality rate in 2014, 2015, and 2016. Conclusions. NTM mortality increased in Japan between 1997 and 2016, especially among the elderly female population. Given the increasing NTM-associated mortality and the susceptible aging population, public health authorities in Japan should pay greater attention to NTM infections.

Automated summary

The study found that NTM-related mortality in Japan increased significantly between 1997 and 2016, particularly among elderly women. The mortality trend was stable in men but increased in women. The NTM-associated mortality rate exceeded tuberculosis mortality rate in women from 2014 to 2016.