Trends in asthma mortality in Japan

Asthma mortality has been increasing in many developed countries in recent years, so we have described the epidemiological features of asthma in Japan. Data on all certified asthma deaths from 1950 to 1997 were obtained from The National Vital Statistics, published annually by the Ministry of Health and Welfare. Trends in crude and age-adjusted asthma mortality rates, as well as age-specific mortality rates, were analyzed. Age and birth cohort effects on mortality rates were also examined using multiplicative models. Between 1950 and 1980, crude asthma mortality rates steadily decreased in both sexes and began to level off thereafter. Age-adjusted mortality rates have also decreased since 1950, and showed a persistent downward trend in both sexes even in recent years. Asthma mortality rates were higher in males than in females during the entire study period. When analysis was restricted to those aged 5 to 34 years, an upward trend since 1980 was observed. The multiplicative model showed a rapidly decreasing cohort effect on mortality among those born after 1860. However, the slope increased in the cohorts born after 1950 in both sexes. The age effect increased linearly with advancing age after 50 years in both sexes. Overall asthma mortality rates have been decreasing during the past five decades in Japan, but the mortality rate has increased among the 5-34-year-old age group since 1980. The high fatality rate stemming from the overuse of beta 2-agonists may account for the mortality increase.