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A statistical analysis has been made of the figures collected during the last eight years in the Edinburgh area, relating to asthmatic patients who presented themselves for examination in certain departments of the Edinburgh Royal Infirmary. The figures for males and females are considered separately, and refer to the numbers of individuals who presented themselves at various, ages, and in whom the disease first manifested itself at various earlier ages. In all, complete records were obtained of 193 males and 167 females. For convenience the ages are grouped in five-year periods.
It has been shown that the figures in the case of females agree well with the assumption that asthmatics, no matter at what age they are first affected, gradually cease to suffer from the disease, or at least fail to report for examination, at a rate which is constant and independent of age. In the case of males the agreement between theory and observation is not as good as in the case of the females, but much of the discrepancy results from two or three obviously aberrant figures. Of every 100 asthmatics at any age it would appear that approximately 7 females, or 8 males as the case may be, are transferred to a non-complaining category every year. The absence of complaint may be due to death from asthma, or recovery, or to some other cause, as for example, that by repeated experience the individual learns how to avoid conditions which precipitate an attack.
On this assumption the relative rates of incidence (P) of the disease at various ages have been calculated for males and for females. Both curves fall during adolescence, rise to a maximum, and then gradually fall, but the male curve lags behind the female curve. From these figures the rates of attack amongst the potential asthmatics (p) have been calculated both for males and for females. The curves fall during adolescence, then rise, remaining practically constant until about 45 years of age, when a rise occurs towards unity. For the further analysis of these curves larger numbers of figures will be necessary, in order that confidence may be placed in the results.
