Age-sex incidence in symptomatic allergies: an excess of females in the child-bearing years.

Eight-hundred and one patients amongst 1912 referred for skin testing because of suspected allergies were found suffering from asthma due to the house-dust mite or from grass pollenosis. They were analysed in terms of sex, age of referral and age of onset of symptoms. Amongst children referred below the age of 10 with house-dust mite asthma the ratio of males to females was 3:1; with grass pollenosis 2-1:1, as expected. The sex ratio gradually became reversed with increasing age of referral, females overtaking males in the third decade. Female-male ratios increased to a mean of 1-8:1 in the fourth and fifth decades. Reliable ages of onset of symptoms were obtained in 388 males and 323 females. Of these, 280 males and 162 females experienced their first symptoms before the age of 10 whereas 96 males and 148 females first developed symptoms between 10 and 29 years of age. The remaining 12 males and 13 females showed their first symptoms after the age of 29.