Age, sex, geographical and socio-economic variations in admissions for anaphylaxis: analysis of four years of English hospital data.

Background Although the most severe of the allergic disorders, the epidemio logy of anaphylaxis remains poorly described. Hospital admissions for anaph ylaxis in England more than doubled during the 1990s. Objective To provide baseline data for assessing future trends, and to asse ss whether there is sufficient regional variation in incidence to allow eff icient testing of aetiological hypotheses, we sought to identify any age, s ex, geographical and socio-economic variations in hospital inpatient admiss ions for anaphylaxis. Methods We studied all emergency admissions for anaphylaxis to English NHS hospitals between 1991 and 1995. Poisson regression modelling was used to c alculate rates of anaphylaxis admission per 100 000 emergency admissions by age, sex, deprivation and by residence in urban/rural, North/South and Eas t/West England. Results Of the 13.5 million emergency inpatient admissions, 2323 patients h ad a primary diagnosis of anaphylaxis. Poisson regression analyses showed s ignificant age, gender; geographical and socio-economic variations in emerg ency admissions for anaphylaxis: adjusted Female rate ratio 1.19 (95% CI 1. 09-1.29), South rate ratio 1.35 (95% CI 1.25-1.47), Rural rate ratio 1.35 ( 95% CI 1.17, 1.59), and Non-deprived rate ratio 1.32 (95% CI 1.19, 1.46). Conclusion This study identifies striking national age, sex, geographical a nd socioeconomic variations in the incidence of inpatient admissions for an aphylaxis in England, affording important opportunities to generate and tes t aetiological hypotheses. Risk of anaphylaxis admission is considerably in creased in females of child-bearing age and those residing in southern, rur al, and affluent areas are independent risk factors for anaphylaxis admissi on.