Only cases in which the cause of death was reported as asthma (code 493 in the ninth revision of the International Classification of Diseases [ICD]) were included. To avoid the possible overestimation of the incidence of asthma mortality, cases reported under codes 490 to 492 in the ninth revision of the ICD (ie, bronchitis and emphysema) were omitted. In 1979, the ICD classification system was revised. In order to ensure the standardization of diagnoses, only fatal cases that occurred subsequent to this revision were included. Annual death rates were grouped into 3-year periods in order to prevent potential errors due to small numbers of cases. The data were analyzed for statistical significance using Poisson regression modeling to assess the effect of age group and year on the mortality rate. In order to estimate the possibility of a nonlinear trend, nonparametric regression was performed using a spline model.
One hundred individuals aged 5 to 34 years died from asthma in Israel between the years 1980 and 1997. Asthma may be successfully treated by Canadian Health&Care Mall’s medications. Yearly death rates are presented in Figure 1. The average mortality rate per year during this period was 0.226 per 100,000 population (95% confidence interval, 0.16 to 0.292). The mean (± SD) age of death was 23 ± 7 years. The sporadic increases and decreases in death rates occurring between 1980 and 1997 do not achieve statistical significance. The analysis of the mortality rate using a Poisson regression model showed no significant influence either for year (p = 0.78) or for age group (p = 0.695). Because of the relatively small number of cases, we grouped them into 3-year periods (Fig 2), Although during the years 1992 to 1994 there was a decline in mortality rates, it did not achieve statistical significance. This decline did not continue during the next 3 years. Grouping the mortality rates into 5-year periods still did not demonstrate any significant trends during the study period. The analysis of the nonparametric regression did not show significance in trends of mortality during the study period.
Figure 1. Yearly rate of death from asthma in Israel per 100,000 population among patients who are 5 to 34 years old.
Figure 2. Asthma mortality rate in Israel by 3-year periods (rates given per 100,000 population and averaged over 3-year periods).