Asthma mortality in Danish children and young adults, 1973-1994: epidemiology and validity of death certificates

Several reports indicate that asthma mortality has increased during the las t few decades. International comparisons reveal some striking differences i n the pattern of asthma mortality. The authors investigated the asthma mort ality rate in the Danish child and youth population 1973-1994 and studied t he validity of death certificates. The authors reviewed all death certificates coded as asthma death in the In ternational Classification of Diseases (TCD 8-ICD 10 (1994)) and adjacent r espiratory code numbers for the age group 1-19 yrs. Hospital records and au topsy reports were assessed to validate the cause of death. Age-standardize d and age-specific mortality rates were calculated. From 1973 to 1987 there was a significant upward trend in the mortality. On subdivision, this trend was limited to the age group 15-19 yrs, Generally the mortality rate decreased from 1988 to 1994. Four per cent coded as asth ma were false positive. Twelve per cent were false negative asthma deaths, wrongly coded as due to other causes, Only 62% of all true positive death c aused by asthma were appropriately coded. The number of false negative cert ifications increased with increasing autopsy frequency. Asthma mortality rates in Denmark increased in adolescents during 1973-1987 and decreased from 1988 to 1994. A possible explanation may be an increase d awareness of asthma symptoms combined with a steadily improved treatment of asthma, Even in children and young adults under the age of 20 yrs, valid ity problems still make comparisons between countries difficult; even inter pretation of national trends requires caution.