Asthma deaths in England and Wales 1931-85: evidence for a true increase in asthma mortality.

A recent increase in asthma mortality has been reported in several countries. Such increases can be brought about by changes in factors acting close to the time of death, but they may also be caused by risk factors determined by the generation into which a person is born, as indicated by the year of birth. Asthma mortality rates since 1931 are independently associated with birthdate as well as date of death. In particular there has been an increase in asthma mortality in birth cohorts born since the 1940s. Such changes are unlikely to be due to a change in reporting of asthma deaths, and other evidence including the reported increase in the prevalence of eczema in succeeding National Birth cohorts supports the view that these changes may be due to an increased prevalence of atopy. In the absence of any further improvements in the management of asthma, such an increased prevalence of atopy implies that the mortality rate is unlikely to decline substantially for some years to come.