Many studies of asthma mortality rely on official registration. The aim of this study was to evaluate the accuracy of death certificates, where asthma was coded as cause of death. In a 12-month period, medical information on all subjects with asthma officially coded as the underlying cause of death in Denmark, was obtained by reviewing hospital records, contacting general practitioners and sometimes close relatives. A panel of four pulmonologists each examined the obtained information and independently assessed the cause of death. Of a total of 218 death certificates, 39 were excluded as the cause of death could not be validated. In 16 (9%) of the subjects death from asthma was judged to be the definite cause of death and in 12 (7%) death from asthma was possible. Of 151 non-asthma deaths coded as due to asthma, 109 were judged to have suffered or died from COPD and 14 from heart disease. The accuracy of Danish death certification in asthma deaths is poor, especially in the elderly, where COPD is often classified as asthma. We conclude that the true asthma mortality in Denmark is substantially lower than officially recorded.
The perimeter of the basement membrane (Pbm) of an airway viewed in cross section is used as a marker of airway size because in normal lungs it is relatively constant, despite variations in airway smooth muscle (ASM) shortening and airway collapse. In vitro studies (McParland BE, Pare PD, Johnson PR, Armour CL, Black JL. J Appl Physiol 97: 556-563, 2004; Noble PB, Sharma A, McFawn PK, Mitchell HW. J Appl Physiol 99: 2061-2066, 2005) have suggested that differential stretch of the Pbm between asthmatic and nonasthmatic airways fixed in inflation may occur and lead to an overestimation of ASM thickness in asthma. The relationships between the Pbm and the area of ASM were compared in transverse sections of airways from cases of fatal asthma (F) and from nonasthmatic control (C) cases where the lung tissue had been fixed inflated (Fi; Ci) or uninflated (Fu; Cu). When all available airways were used, the regression slopes were increased in Fu and Cu, compared with Fi and Ci, and increased in Fu and Fi, compared with Cu and Ci, suggesting effects of both inflation and asthma group, respectively. When analyses were limited to airway sizes that were available for all groups (Pbm
The objective of the present study was to investigate mortality attributable to asthma in different occupations. The mortality from asthma among Swedish workers between 1981 and 1992 was investigated by a linkage between official mortality statistics and the occupational information in the 1980 National Census. For each occupation, a smoking-adjusted standardized mortality ratio (SMR) was calculated. The information about smoking habits was obtained from smoking surveys carried out from 1977 to 1979. Only occupations with more than five cases were considered in the analysis. Significantly increased mortality from asthma was found among male farmers (smoking-adjusted SMR = 146; 95% confidence interval [CI] 105-187) and male professional drivers (smoking-adjusted SMR = 144, 95% CI = 101-209) and female hairdressers (smoking-adjusted SMR = 332, 95% CI = 102-525). The increased mortality among three occupational groups (hairdressers, farmers, and professional drivers) out of 46 groups analyzed may be random occurrences. However, farmers and hairdressers are exposed to agents causing asthma, indicating that the increased mortality may be attributable to occupational exposure.
Several reports indicate that asthma mortality has increased during the last few decades. International comparisons reveal some striking differences in the pattern of asthma mortality. The authors investigated the asthma mortality rate in the Danish child and youth population 1973-1994 and studied the validity of death certificates. The authors reviewed all death certificates coded as asthma death in the International Classification of Diseases (ICD 8-ICD 10 (1994)) and adjacent respiratory code numbers for the age group 1-19 yrs. Hospital records and autopsy reports were assessed to validate the cause of death. Age-standardized 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 asthma 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 caused by asthma were appropriately coded. The number of false negative certifications 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 increased awareness of asthma symptoms combined with a steadily improved treatment of asthma. Even in children and young adults under the age of 20 yrs, validity problems still make comparisons between countries difficult; even interpretation of national trends requires caution.
Deaths caused by asthma are now recognized in all western countries, but they were only lately accepted in France because Laennec and Trousseau denied that patients with asthma may die of asthma. The "epidemic" of asthma deaths of the 1960s was not observed. Since 1968, it appears that asthma deaths decreased until 1974 for females and until 1980 for males, and then increased up to 2.9/100,000 in males and 3.6/100,000 for females. In the age group 5 to 34 years, there is a slight increase of deaths caused by asthma with a death rate of 0.35/100,000 in males and 0.39/100,000 in females. The ninth revision of the ICD did not lead to an increase in the number of reported deaths caused by asthma. In Denmark, death rates in the age group 5 to 34 years are similar to those in France, but in Germany they are much greater in number, and a clear increase was noticed. The causes of death of individuals with asthma in France are similar to causes reported in other countries, but deaths caused by specific immunotherapy may be more frequent because asthma is often treated by this form of therapy. Moreover, some deaths were associated with "corticophobia," with many patients preferring to use homeopathy or acupuncture.
There is evidence that mortality due to asthma has increased in a number of nations over the last two decades. This study was conducted to assess asthma mortality rates in Russia from 1980 to 1989. Data obtained were compared with figures from other countries. National asthma deaths were obtained from the Ministry of Health of the Russian Federation. Age- and sex-specific rates per 100,000 population per year were adjusted to the European population. Annual changes in mortality rates for the study period were estimated by linear regression analysis. Between 1980 and 1989, asthma mortality rates per 100,000 population per year increased from 3.7 to 5.3 in the total Russian population. Differences according to age and sex were observed. Asthma deaths increased with age and in most cases males showed higher death rates than females. There was a statistically significant annual increase in mortality rates for young males or = 65 yrs. Asthma mortality rates in Russia between 1980 and 1989 may be considered moderate as compared with death rates reported for the same period in other countries.