Trends in reported annual asthma mortality rates for people aged five to 34 years between 1970 and 1984/5 are shown in Figure 1. For clarity, only data on eight countries are shown. Table 1 gives the average asthma mortality in three-year periods between 1970 and 1984 for each of the 14 countries. There was a wide variation in asthma mortality rates and mortality trends among countries. Throughout the 15-year period under consideration; New Zealand has consistently had the highest mortality rates while the lowest rates were reported in the United States, the Netherlands, France, and Finland. The difference in asthma death rates between New Zealand and these four countries is as much as tenfold. Figure 1 shows the previously reported rapid increase in asthma mortality in young people in New Zealand between 1975 and 1979, when the death rate trebled from 1.3 to 4.1 per 100,000. Since 1982, the mortality rate has declined almost as abruptly as it increased and by 1985 had fallen to 1.85 per 100,000. None of the other countries examined experienced major increases in reported asthma death rates during the period 1970 to 1984/5, but a gradual increase since the mid-1970s is apparent in all other countries except in Finland and Switzerland. It should be stressed that the annual number of asthma deaths in some countries was small (Table 1); in these countries, the calculated percentage changes in death rates are, therefore, intrinsically unstable. canada health and care mall
With the exception of Finland, Sweden, and Switzerland, all countries studied introduced the ninth revision of the ICD in 1979. There was, however, little or no change in the mortality rates from asthma between 1978 and 1979 in any of the countries investigated, except in New Zealand, which suggests that the ICD change had only a minor effect on reported asthma mortality rates in this age group (Fig 1).
A comparison of the mean three-year rates for 1976 to 1978 and 1982 to 1984 shows increases of 20 percent or more in Australia, Canada, England and Wales, the Netherlands, Sweden, the United States, and West Germany. Furthermore, the general trend of increasing asthma mortality continued after the introduction of ICD 9. Eleven of the 14 countries examined had a higher average mortality in 1982 to 1984 than in 1979 to 1981 (Table 1); in six countries, this increase was 20 percent or more.
Figure 2 shows trends in reported asthma mortality and in mortality from all respiratory disease other than asthma in New Zealand, England and Wales, and the United States in people aged five to 34 years. The increase and subsequent decline in asthma mortality between 1970 and 1985 in New Zealand is clearly not associated with reciprocal trends in deaths for other respiratory diseases. In England and Wales and in the United States, the increases in asthma mortality coincide with a decline in all other reported respiratory disease deaths. Numerically a transfer of deaths from other respiratory categories to asthma could therefore account for the recent increase in asthma mortality rates in these two countries. However, a more detailed breakdown of respiratory disease mortality data from the United States (Fig 3) indicate that total deaths due to any form of obstructive airways disease in the five-to 34-years age group have increased since the late 1970s. As a change in diagnostic fashions is most likely to involve a shift within the obstructive airway disease categories, for example from bronchitis or emphysema to asthma, this suggests that the reported increase in asthma deaths in young people in the United States is, in fact, real. This conclusion may not be relevant for the older age groups.
Table 1—Asthma Mortality by Three-Year Time Periods 1970 to 1984* (Rates Fer 200,000 Population Averaged Over Three-Year Periods Five- to 34-Year-Old Subjects)
|Country (Annual No. of Deaths)^||1970-72||1973-75||1976-78||1979-81||1982-84||Percentage Increase Between:|
|New Zealand (21-68)||1.93||1.38||2.86||3.63||2.67||-7||-28|
|West Germany (108-227)||0.44||0.51||0.66||0.82||0.83||26||1|
|United States (183-408)||0.29||0.22||0.19||0.26||0.34||78||31|
Figure 1. Asthma mortality in people aged five to 34 years, 1970 to 1984/5 in eight countries.
Figure 2. Asthma mortality and mortality from all other respiratory diseases in people aged five to 34 years, 1970 to 1984/5 in three countries.
Figure 3. Mortality due to all obstructive airways diseases classified by disease category in people aged five to 34 years, 1970 to 1984 in the United States.