Population-Based Observational Study of Adverse Drug Event-Related Mortality in the Super-Aged Society of Japan

Adverse drug events (ADEs) are a major cause of mortality. We examined long-term trends for ADE-related deaths in Japan. This observational study was conducted using the Japanese Vital Statistics from 1999 to 2016. Data for all ADE-related deaths were extracted using International Classification of Diseases, Tenth Revision codes. We analysed ADE-related deaths by age and sex and calculated crude and age-standardised mortality rates (ASMR) per 100,000 people. We used Joinpoint regression analysis to identify significant changing points in mortality trends and to estimate annual percentage change (APC). In total, 16,417 ADE-related deaths were identified. The crude mortality rate for individuals aged ≥ 65 years was higher than that of young individuals. The ASMR per 100,000 people increased from 0.44 in 1999 to 0.64 in 2016. The crude mortality rate increased from 0.44 in 1999 to 1.01 in 2016. The APC of ASMR increased at a rate of 2.8% (95% confidence interval [CI] 1.4–4.2) throughout the study period. In addition, crude mortality increased at a rate of 5.7% (95% CI 4.2–7.3) annually from 1999 to 2016. The ADE-related mortality rate was higher for men than for women during the study period. The number of and trend in ADE-related deaths increased in Japan from 1999 to 2016, particularly in the older population. Adverse drug events (ADEs) are a public health issue, but descriptive data on ADEs in Japan are limited. Studies have shown that elderly people have a higher risk of dying from ADEs. Japan has one of the most rapidly aging populations and the highest percentage of older individuals worldwide. Clarifying long-term data trends in Japan is important in the aging world. Here, we aimed to clarify the trend in mortality related to ADEs in Japan. We selected 16,417 deaths that were assigned an underlying cause (i.e., ADEs) in vital statistics based on codes from the International Classification of Diseases, Tenth Revision (ICD-10). The crude mortality rate for both sexes increased from 0.44 per 100,000 in 1999 to 1.01 in 2016. The average annual percentage change (average APC), which numerically shows the change over time, was 5.7% throughout the study period. The age-standardised mortality rate, using the population in the first year, increased from 0.44 per 100,000 in 1999 to 0.64 in 2016. The average APC of the age-standardised mortality rate showed an increasing trend at 2.8%. Even after age standardisation, ADE-associated death showed an increasing trend. In particular, population groups aged ≥65 years showed a continuous increasing trend. These findings suggest that the ADE-related mortality rate in Japan is increasing, especially in elderly individuals.