Seasonal patterns in asthma hospitalization rates in Saskatchewan
Sreelatha, Thekke Cheruvath
Objectives Monthly hospitalization rates in Saskatchewan from January 1979 to December 1989 were examined in order to see if they exhibited a seasonal pattern. The agegroups studied were 0-4, 5-14, 15-34, 35-49 and 50-64. Male and females rates, as well as native and non-native patterns were compared to see if the patterns differed by sex or race. Methods The method used was that of decomposing the time series into its trend, seasonal and error component, using an additive model. The significance of the components was tested using a two-way ANOVA. Results The monthly asthma hospitalization rates for non-natives in Sakatchewan did exhibit seasonal variation. The pattern seen was that of a spring and fall peak in the children, a fall peak in young adults and a winter-spring peak in the older groups. There was a difference between the sexes among the adults. Women seem to be more affected by the aeroallergens in spring than men. The 35-49 year old men did not have a statistically significant seasonal pattern, whereas the women did. The native and non-native patterns compared for the first time in this study, do show different patterns for the different populations. Only the oldest group had the same seasonal pattern as seen in the non-natives. Conclusions: Asthma hospitalization rates for non-natives in Saskatchewan do exhibit seasonal patterns. The results are similar to those seen in other parts of the world. The sex specific patterns for the age groups studied do not seem to have been examined before. The adult sex specific patterns did indicate some differences between the sexes. The native and non-native patterns were also quite different. More studies need to be done in order to find reasons for the differences seen in this study.