Trends in the nontuberculous mycobacterial disease mortality rate in Japan: A nationwide observational study, 1997-2016
Abstract 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 (TB)-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 males of all ages and females aged 40–59 years were stable but increased among females 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 males, the age-adjusted mortality rates did not show a significant trend, while among females, the rates increased over the study period (AAPC: 4.6%, 95% CI: 2.7–6.6%). In females, the crude NTM-associated mortality rate exceeded the TB 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 susceptible aging population, public health authorities in Japan should pay greater attention to NTM infections.