Mortality from airways disorders in Alberta, 1927-1987: an expanding epidemic of COPD, but asthma shows little change.

Mortality from asthma has been reported to be increasing in recent years in many countries, including Canada. Alberta, and the prairie provinces generally, appear to have an excess of deaths from asthma compared to other provinces. We studied mortality from asthma and from chronic obstructive pulmonary disease (COPD) generally in Alberta between 1927 and 1987 using a data set compiled and recorded from Alberta Vital Statistics to describe birth cohorts' age-specific mortality rates. We also present the distribution of deaths in the years since 1987. There was a clear and sustained increase in mortality from COPD since 1950 after age 40 but no evidence to support the proposition that deaths from asthma were increasing in recent years; more recent data from Alberta Vital Statistics show no sustained increase since 1987, either. There was great variability from year to year and sporadically increased rates in a given year that were not sustained. These transient increases were observed particularly among females aged 10-14, 15-19, and 25-29 and among males aged 15-19, 25-29, and 80-84; however, there were also comparable decreases in asthma mortality of similar magnitude during the same time period in different age groups or in the other sex in the age group 10-14. We conclude that there is no excess of deaths from asthma over those expected by historical trends in Alberta at the present time but that the smoking-related epidemic of deaths from COPD continues unabated. The "smoothness" and consistency of the mortality trends suggest that physicians certifying deaths from these causes are using implicit diagnostic criteria that have not changed abruptly.